sample conclusion for research

How to Write a Conclusion for Research Papers (with Examples)

The conclusion of a research paper is a crucial section that plays a significant role in the overall impact and effectiveness of your research paper. However, this is also the section that typically receives less attention compared to the introduction and the body of the paper. The conclusion serves to provide a concise summary of the key findings, their significance, their implications, and a sense of closure to the study. Discussing how can the findings be applied in real-world scenarios or inform policy, practice, or decision-making is especially valuable to practitioners and policymakers. The research paper conclusion also provides researchers with clear insights and valuable information for their own work, which they can then build on and contribute to the advancement of knowledge in the field.

The research paper conclusion should explain the significance of your findings within the broader context of your field. It restates how your results contribute to the existing body of knowledge and whether they confirm or challenge existing theories or hypotheses. Also, by identifying unanswered questions or areas requiring further investigation, your awareness of the broader research landscape can be demonstrated.

Remember to tailor the research paper conclusion to the specific needs and interests of your intended audience, which may include researchers, practitioners, policymakers, or a combination of these.

Table of Contents

What is a conclusion in a research paper, summarizing conclusion, editorial conclusion, externalizing conclusion, importance of a good research paper conclusion, how to write a conclusion for your research paper, research paper conclusion examples.

• How to write a research paper conclusion with Paperpal? 

Frequently Asked Questions

A conclusion in a research paper is the final section where you summarize and wrap up your research, presenting the key findings and insights derived from your study. The research paper conclusion is not the place to introduce new information or data that was not discussed in the main body of the paper. When working on how to conclude a research paper, remember to stick to summarizing and interpreting existing content. The research paper conclusion serves the following purposes: 1

• Warn readers of the possible consequences of not attending to the problem.
• Recommend specific course(s) of action.
• Restate key ideas to drive home the ultimate point of your research paper.
• Provide a “take-home” message that you want the readers to remember about your study.

Types of conclusions for research papers

In research papers, the conclusion provides closure to the reader. The type of research paper conclusion you choose depends on the nature of your study, your goals, and your target audience. I provide you with three common types of conclusions:

A summarizing conclusion is the most common type of conclusion in research papers. It involves summarizing the main points, reiterating the research question, and restating the significance of the findings. This common type of research paper conclusion is used across different disciplines.

An editorial conclusion is less common but can be used in research papers that are focused on proposing or advocating for a particular viewpoint or policy. It involves presenting a strong editorial or opinion based on the research findings and offering recommendations or calls to action.

An externalizing conclusion is a type of conclusion that extends the research beyond the scope of the paper by suggesting potential future research directions or discussing the broader implications of the findings. This type of conclusion is often used in more theoretical or exploratory research papers.

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The conclusion in a research paper serves several important purposes:

• Offers Implications and Recommendations : Your research paper conclusion is an excellent place to discuss the broader implications of your research and suggest potential areas for further study. It’s also an opportunity to offer practical recommendations based on your findings.
• Provides Closure : A good research paper conclusion provides a sense of closure to your paper. It should leave the reader with a feeling that they have reached the end of a well-structured and thought-provoking research project.
• Leaves a Lasting Impression : Writing a well-crafted research paper conclusion leaves a lasting impression on your readers. It’s your final opportunity to leave them with a new idea, a call to action, or a memorable quote.

Writing a strong conclusion for your research paper is essential to leave a lasting impression on your readers. Here’s a step-by-step process to help you create and know what to put in the conclusion of a research paper: 2

• Research Statement : Begin your research paper conclusion by restating your research statement. This reminds the reader of the main point you’ve been trying to prove throughout your paper. Keep it concise and clear.
• Key Points : Summarize the main arguments and key points you’ve made in your paper. Avoid introducing new information in the research paper conclusion. Instead, provide a concise overview of what you’ve discussed in the body of your paper.
• Address the Research Questions : If your research paper is based on specific research questions or hypotheses, briefly address whether you’ve answered them or achieved your research goals. Discuss the significance of your findings in this context.
• Significance : Highlight the importance of your research and its relevance in the broader context. Explain why your findings matter and how they contribute to the existing knowledge in your field.
• Implications : Explore the practical or theoretical implications of your research. How might your findings impact future research, policy, or real-world applications? Consider the “so what?” question.
• Future Research : Offer suggestions for future research in your area. What questions or aspects remain unanswered or warrant further investigation? This shows that your work opens the door for future exploration.
• Closing Thought : Conclude your research paper conclusion with a thought-provoking or memorable statement. This can leave a lasting impression on your readers and wrap up your paper effectively. Avoid introducing new information or arguments here.
• Proofread and Revise : Carefully proofread your conclusion for grammar, spelling, and clarity. Ensure that your ideas flow smoothly and that your conclusion is coherent and well-structured.

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Remember that a well-crafted research paper conclusion is a reflection of the strength of your research and your ability to communicate its significance effectively. It should leave a lasting impression on your readers and tie together all the threads of your paper. Now you know how to start the conclusion of a research paper and what elements to include to make it impactful, let’s look at a research paper conclusion sample.

How to write a research paper conclusion with Paperpal?

A research paper conclusion is not just a summary of your study, but a synthesis of the key findings that ties the research together and places it in a broader context. A research paper conclusion should be concise, typically around one paragraph in length. However, some complex topics may require a longer conclusion to ensure the reader is left with a clear understanding of the study’s significance. Paperpal, an AI writing assistant trusted by over 800,000 academics globally, can help you write a well-structured conclusion for your research paper. 

• Sign Up or Log In: Create a new Paperpal account or login with your details.  
• Navigate to Features : Once logged in, head over to the features’ side navigation pane. Click on Templates and you’ll find a suite of generative AI features to help you write better, faster.  
• Generate an outline: Under Templates, select ‘Outlines’. Choose ‘Research article’ as your document type.  
• Select your section: Since you’re focusing on the conclusion, select this section when prompted.  
• Choose your field of study: Identifying your field of study allows Paperpal to provide more targeted suggestions, ensuring the relevance of your conclusion to your specific area of research. 
• Provide a brief description of your study: Enter details about your research topic and findings. This information helps Paperpal generate a tailored outline that aligns with your paper’s content. 
• Generate the conclusion outline: After entering all necessary details, click on ‘generate’. Paperpal will then create a structured outline for your conclusion, to help you start writing and build upon the outline.  
• Write your conclusion: Use the generated outline to build your conclusion. The outline serves as a guide, ensuring you cover all critical aspects of a strong conclusion, from summarizing key findings to highlighting the research’s implications. 
• Refine and enhance: Paperpal’s ‘Make Academic’ feature can be particularly useful in the final stages. Select any paragraph of your conclusion and use this feature to elevate the academic tone, ensuring your writing is aligned to the academic journal standards. 

By following these steps, Paperpal not only simplifies the process of writing a research paper conclusion but also ensures it is impactful, concise, and aligned with academic standards. Sign up with Paperpal today and write your research paper conclusion 2x faster .  

The research paper conclusion is a crucial part of your paper as it provides the final opportunity to leave a strong impression on your readers. In the research paper conclusion, summarize the main points of your research paper by restating your research statement, highlighting the most important findings, addressing the research questions or objectives, explaining the broader context of the study, discussing the significance of your findings, providing recommendations if applicable, and emphasizing the takeaway message. The main purpose of the conclusion is to remind the reader of the main point or argument of your paper and to provide a clear and concise summary of the key findings and their implications. All these elements should feature on your list of what to put in the conclusion of a research paper to create a strong final statement for your work.

A strong conclusion is a critical component of a research paper, as it provides an opportunity to wrap up your arguments, reiterate your main points, and leave a lasting impression on your readers. Here are the key elements of a strong research paper conclusion: 1. Conciseness : A research paper conclusion should be concise and to the point. It should not introduce new information or ideas that were not discussed in the body of the paper. 2. Summarization : The research paper conclusion should be comprehensive enough to give the reader a clear understanding of the research’s main contributions. 3 . Relevance : Ensure that the information included in the research paper conclusion is directly relevant to the research paper’s main topic and objectives; avoid unnecessary details. 4 . Connection to the Introduction : A well-structured research paper conclusion often revisits the key points made in the introduction and shows how the research has addressed the initial questions or objectives. 5. Emphasis : Highlight the significance and implications of your research. Why is your study important? What are the broader implications or applications of your findings? 6 . Call to Action : Include a call to action or a recommendation for future research or action based on your findings.

The length of a research paper conclusion can vary depending on several factors, including the overall length of the paper, the complexity of the research, and the specific journal requirements. While there is no strict rule for the length of a conclusion, but it’s generally advisable to keep it relatively short. A typical research paper conclusion might be around 5-10% of the paper’s total length. For example, if your paper is 10 pages long, the conclusion might be roughly half a page to one page in length.

In general, you do not need to include citations in the research paper conclusion. Citations are typically reserved for the body of the paper to support your arguments and provide evidence for your claims. However, there may be some exceptions to this rule: 1. If you are drawing a direct quote or paraphrasing a specific source in your research paper conclusion, you should include a citation to give proper credit to the original author. 2. If your conclusion refers to or discusses specific research, data, or sources that are crucial to the overall argument, citations can be included to reinforce your conclusion’s validity.

The conclusion of a research paper serves several important purposes: 1. Summarize the Key Points 2. Reinforce the Main Argument 3. Provide Closure 4. Offer Insights or Implications 5. Engage the Reader. 6. Reflect on Limitations

Remember that the primary purpose of the research paper conclusion is to leave a lasting impression on the reader, reinforcing the key points and providing closure to your research. It’s often the last part of the paper that the reader will see, so it should be strong and well-crafted.

• Makar, G., Foltz, C., Lendner, M., & Vaccaro, A. R. (2018). How to write effective discussion and conclusion sections. Clinical spine surgery, 31(8), 345-346.
• Bunton, D. (2005). The structure of PhD conclusion chapters.  Journal of English for academic purposes ,  4 (3), 207-224.

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Home » Research Paper Conclusion – Writing Guide and Examples

Research Paper Conclusion – Writing Guide and Examples

Table of Contents

Research Paper Conclusion

Definition:

A research paper conclusion is the final section of a research paper that summarizes the key findings, significance, and implications of the research. It is the writer’s opportunity to synthesize the information presented in the paper, draw conclusions, and make recommendations for future research or actions.

The conclusion should provide a clear and concise summary of the research paper, reiterating the research question or problem, the main results, and the significance of the findings. It should also discuss the limitations of the study and suggest areas for further research.

Parts of Research Paper Conclusion

The parts of a research paper conclusion typically include:

Restatement of the Thesis

The conclusion should begin by restating the thesis statement from the introduction in a different way. This helps to remind the reader of the main argument or purpose of the research.

Summary of Key Findings

The conclusion should summarize the main findings of the research, highlighting the most important results and conclusions. This section should be brief and to the point.

Implications and Significance

In this section, the researcher should explain the implications and significance of the research findings. This may include discussing the potential impact on the field or industry, highlighting new insights or knowledge gained, or pointing out areas for future research.

Limitations and Recommendations

It is important to acknowledge any limitations or weaknesses of the research and to make recommendations for how these could be addressed in future studies. This shows that the researcher is aware of the potential limitations of their work and is committed to improving the quality of research in their field.

Concluding Statement

The conclusion should end with a strong concluding statement that leaves a lasting impression on the reader. This could be a call to action, a recommendation for further research, or a final thought on the topic.

How to Write Research Paper Conclusion

Here are some steps you can follow to write an effective research paper conclusion:

• Restate the research problem or question: Begin by restating the research problem or question that you aimed to answer in your research. This will remind the reader of the purpose of your study.
• Summarize the main points: Summarize the key findings and results of your research. This can be done by highlighting the most important aspects of your research and the evidence that supports them.
• Discuss the implications: Discuss the implications of your findings for the research area and any potential applications of your research. You should also mention any limitations of your research that may affect the interpretation of your findings.
• Provide a conclusion : Provide a concise conclusion that summarizes the main points of your paper and emphasizes the significance of your research. This should be a strong and clear statement that leaves a lasting impression on the reader.
• Offer suggestions for future research: Lastly, offer suggestions for future research that could build on your findings and contribute to further advancements in the field.

Remember that the conclusion should be brief and to the point, while still effectively summarizing the key findings and implications of your research.

Example of Research Paper Conclusion

Here’s an example of a research paper conclusion:

Conclusion :

In conclusion, our study aimed to investigate the relationship between social media use and mental health among college students. Our findings suggest that there is a significant association between social media use and increased levels of anxiety and depression among college students. This highlights the need for increased awareness and education about the potential negative effects of social media use on mental health, particularly among college students.

Despite the limitations of our study, such as the small sample size and self-reported data, our findings have important implications for future research and practice. Future studies should aim to replicate our findings in larger, more diverse samples, and investigate the potential mechanisms underlying the association between social media use and mental health. In addition, interventions should be developed to promote healthy social media use among college students, such as mindfulness-based approaches and social media detox programs.

Overall, our study contributes to the growing body of research on the impact of social media on mental health, and highlights the importance of addressing this issue in the context of higher education. By raising awareness and promoting healthy social media use among college students, we can help to reduce the negative impact of social media on mental health and improve the well-being of young adults.

Purpose of Research Paper Conclusion

The purpose of a research paper conclusion is to provide a summary and synthesis of the key findings, significance, and implications of the research presented in the paper. The conclusion serves as the final opportunity for the writer to convey their message and leave a lasting impression on the reader.

The conclusion should restate the research problem or question, summarize the main results of the research, and explain their significance. It should also acknowledge the limitations of the study and suggest areas for future research or action.

Overall, the purpose of the conclusion is to provide a sense of closure to the research paper and to emphasize the importance of the research and its potential impact. It should leave the reader with a clear understanding of the main findings and why they matter. The conclusion serves as the writer’s opportunity to showcase their contribution to the field and to inspire further research and action.

When to Write Research Paper Conclusion

The conclusion of a research paper should be written after the body of the paper has been completed. It should not be written until the writer has thoroughly analyzed and interpreted their findings and has written a complete and cohesive discussion of the research.

Before writing the conclusion, the writer should review their research paper and consider the key points that they want to convey to the reader. They should also review the research question, hypotheses, and methodology to ensure that they have addressed all of the necessary components of the research.

Once the writer has a clear understanding of the main findings and their significance, they can begin writing the conclusion. The conclusion should be written in a clear and concise manner, and should reiterate the main points of the research while also providing insights and recommendations for future research or action.

Characteristics of Research Paper Conclusion

The characteristics of a research paper conclusion include:

• Clear and concise: The conclusion should be written in a clear and concise manner, summarizing the key findings and their significance.
• Comprehensive: The conclusion should address all of the main points of the research paper, including the research question or problem, the methodology, the main results, and their implications.
• Future-oriented : The conclusion should provide insights and recommendations for future research or action, based on the findings of the research.
• Impressive : The conclusion should leave a lasting impression on the reader, emphasizing the importance of the research and its potential impact.
• Objective : The conclusion should be based on the evidence presented in the research paper, and should avoid personal biases or opinions.
• Unique : The conclusion should be unique to the research paper and should not simply repeat information from the introduction or body of the paper.

Advantages of Research Paper Conclusion

The advantages of a research paper conclusion include:

• Summarizing the key findings : The conclusion provides a summary of the main findings of the research, making it easier for the reader to understand the key points of the study.
• Emphasizing the significance of the research: The conclusion emphasizes the importance of the research and its potential impact, making it more likely that readers will take the research seriously and consider its implications.
• Providing recommendations for future research or action : The conclusion suggests practical recommendations for future research or action, based on the findings of the study.
• Providing closure to the research paper : The conclusion provides a sense of closure to the research paper, tying together the different sections of the paper and leaving a lasting impression on the reader.
• Demonstrating the writer’s contribution to the field : The conclusion provides the writer with an opportunity to showcase their contribution to the field and to inspire further research and action.

Limitations of Research Paper Conclusion

While the conclusion of a research paper has many advantages, it also has some limitations that should be considered, including:

• I nability to address all aspects of the research: Due to the limited space available in the conclusion, it may not be possible to address all aspects of the research in detail.
• Subjectivity : While the conclusion should be objective, it may be influenced by the writer’s personal biases or opinions.
• Lack of new information: The conclusion should not introduce new information that has not been discussed in the body of the research paper.
• Lack of generalizability: The conclusions drawn from the research may not be applicable to other contexts or populations, limiting the generalizability of the study.
• Misinterpretation by the reader: The reader may misinterpret the conclusions drawn from the research, leading to a misunderstanding of the findings.

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How to write a strong conclusion for your research paper

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17 February 2024

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Writing a research paper is a chance to share your knowledge and hypothesis. It's an opportunity to demonstrate your many hours of research and prove your ability to write convincingly.

Ideally, by the end of your research paper, you'll have brought your readers on a journey to reach the conclusions you've pre-determined. However, if you don't stick the landing with a good conclusion, you'll risk losing your reader’s trust.

Writing a strong conclusion for your research paper involves a few important steps, including restating the thesis and summing up everything properly.

Find out what to include and what to avoid, so you can effectively demonstrate your understanding of the topic and prove your expertise.

• Why is a good conclusion important?

A good conclusion can cement your paper in the reader’s mind. Making a strong impression in your introduction can draw your readers in, but it's the conclusion that will inspire them.

• What to include in a research paper conclusion

There are a few specifics you should include in your research paper conclusion. Offer your readers some sense of urgency or consequence by pointing out why they should care about the topic you have covered. Discuss any common problems associated with your topic and provide suggestions as to how these problems can be solved or addressed.

The conclusion should include a restatement of your initial thesis. Thesis statements are strengthened after you’ve presented supporting evidence (as you will have done in the paper), so make a point to reintroduce it at the end.

Finally, recap the main points of your research paper, highlighting the key takeaways you want readers to remember. If you've made multiple points throughout the paper, refer to the ones with the strongest supporting evidence.

• Steps for writing a research paper conclusion

Many writers find the conclusion the most challenging part of any research project . By following these three steps, you'll be prepared to write a conclusion that is effective and concise.

• Step 1: Restate the problem

Always begin by restating the research problem in the conclusion of a research paper. This serves to remind the reader of your hypothesis and refresh them on the main point of the paper. 

When restating the problem, take care to avoid using exactly the same words you employed earlier in the paper.

• Step 2: Sum up the paper

After you've restated the problem, sum up the paper by revealing your overall findings. The method for this differs slightly, depending on whether you're crafting an argumentative paper or an empirical paper.

Argumentative paper: Restate your thesis and arguments

Argumentative papers involve introducing a thesis statement early on. In crafting the conclusion for an argumentative paper, always restate the thesis, outlining the way you've developed it throughout the entire paper.

It might be appropriate to mention any counterarguments in the conclusion, so you can demonstrate how your thesis is correct or how the data best supports your main points.

Empirical paper: Summarize research findings

Empirical papers break down a series of research questions. In your conclusion, discuss the findings your research revealed, including any information that surprised you.

Be clear about the conclusions you reached, and explain whether or not you expected to arrive at these particular ones.

• Step 3: Discuss the implications of your research

Argumentative papers and empirical papers also differ in this part of a research paper conclusion. Here are some tips on crafting conclusions for argumentative and empirical papers.

Argumentative paper: Powerful closing statement

In an argumentative paper, you'll have spent a great deal of time expressing the opinions you formed after doing a significant amount of research. Make a strong closing statement in your argumentative paper's conclusion to share the significance of your work.

You can outline the next steps through a bold call to action, or restate how powerful your ideas turned out to be.

Empirical paper: Directions for future research

Empirical papers are broader in scope. They usually cover a variety of aspects and can include several points of view.

To write a good conclusion for an empirical paper, suggest the type of research that could be done in the future, including methods for further investigation or outlining ways other researchers might proceed.

If you feel your research had any limitations, even if they were outside your control, you could mention these in your conclusion.

After you finish outlining your conclusion, ask someone to read it and offer feedback. In any research project you're especially close to, it can be hard to identify problem areas. Having a close friend or someone whose opinion you value read the research paper and provide honest feedback can be invaluable. Take note of any suggested edits and consider incorporating them into your paper if they make sense.

• Things to avoid in a research paper conclusion

Keep these aspects to avoid in mind as you're writing your conclusion and refer to them after you've created an outline.

Dry summary

Writing a memorable, succinct conclusion is arguably more important than a strong introduction. Take care to avoid just rephrasing your main points, and don't fall into the trap of repeating dry facts or citations.

You can provide a new perspective for your readers to think about or contextualize your research. Either way, make the conclusion vibrant and interesting, rather than a rote recitation of your research paper’s highlights.

Clichéd or generic phrasing

Your research paper conclusion should feel fresh and inspiring. Avoid generic phrases like "to sum up" or "in conclusion." These phrases tend to be overused, especially in an academic context and might turn your readers off.

The conclusion also isn't the time to introduce colloquial phrases or informal language. Retain a professional, confident tone consistent throughout your paper’s conclusion so it feels exciting and bold.

New data or evidence

While you should present strong data throughout your paper, the conclusion isn't the place to introduce new evidence. This is because readers are engaged in actively learning as they read through the body of your paper.

By the time they reach the conclusion, they will have formed an opinion one way or the other (hopefully in your favor!). Introducing new evidence in the conclusion will only serve to surprise or frustrate your reader.

Ignoring contradictory evidence

If your research reveals contradictory evidence, don't ignore it in the conclusion. This will damage your credibility as an expert and might even serve to highlight the contradictions.

Be as transparent as possible and admit to any shortcomings in your research, but don't dwell on them for too long.

Ambiguous or unclear resolutions

The point of a research paper conclusion is to provide closure and bring all your ideas together. You should wrap up any arguments you introduced in the paper and tie up any loose ends, while demonstrating why your research and data are strong.

Use direct language in your conclusion and avoid ambiguity. Even if some of the data and sources you cite are inconclusive or contradictory, note this in your conclusion to come across as confident and trustworthy.

• Examples of research paper conclusions

Your research paper should provide a compelling close to the paper as a whole, highlighting your research and hard work. While the conclusion should represent your unique style, these examples offer a starting point:

Ultimately, the data we examined all point to the same conclusion: Encouraging a good work-life balance improves employee productivity and benefits the company overall. The research suggests that when employees feel their personal lives are valued and respected by their employers, they are more likely to be productive when at work. In addition, company turnover tends to be reduced when employees have a balance between their personal and professional lives. While additional research is required to establish ways companies can support employees in creating a stronger work-life balance, it's clear the need is there.

Social media is a primary method of communication among young people. As we've seen in the data presented, most young people in high school use a variety of social media applications at least every hour, including Instagram and Facebook. While social media is an avenue for connection with peers, research increasingly suggests that social media use correlates with body image issues. Young girls with lower self-esteem tend to use social media more often than those who don't log onto social media apps every day. As new applications continue to gain popularity, and as more high school students are given smartphones, more research will be required to measure the effects of prolonged social media use.

What are the different kinds of research paper conclusions?

There are no formal types of research paper conclusions. Ultimately, the conclusion depends on the outline of your paper and the type of research you’re presenting. While some experts note that research papers can end with a new perspective or commentary, most papers should conclude with a combination of both. The most important aspect of a good research paper conclusion is that it accurately represents the body of the paper.

Can I present new arguments in my research paper conclusion?

Research paper conclusions are not the place to introduce new data or arguments. The body of your paper is where you should share research and insights, where the reader is actively absorbing the content. By the time a reader reaches the conclusion of the research paper, they should have formed their opinion. Introducing new arguments in the conclusion can take a reader by surprise, and not in a positive way. It might also serve to frustrate readers.

How long should a research paper conclusion be?

There's no set length for a research paper conclusion. However, it's a good idea not to run on too long, since conclusions are supposed to be succinct. A good rule of thumb is to keep your conclusion around 5 to 10 percent of the paper's total length. If your paper is 10 pages, try to keep your conclusion under one page.

What should I include in a research paper conclusion?

A good research paper conclusion should always include a sense of urgency, so the reader can see how and why the topic should matter to them. You can also note some recommended actions to help fix the problem and some obstacles they might encounter. A conclusion should also remind the reader of the thesis statement, along with the main points you covered in the paper. At the end of the conclusion, add a powerful closing statement that helps cement the paper in the mind of the reader.

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How to Write Conclusion in Research Paper (With Example)

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Writing a strong conclusion is a crucial part of any research paper. It provides a final opportunity to summarize your key findings, restate your thesis, and leave a lasting impression on your reader. However, many students struggle with how to effectively write a conclusion that ties everything together.

In this article, we’ll provide some tips and strategies for writing a compelling conclusion, along with an example to help illustrate the process. By following these guidelines, you can ensure that your research paper ends on a high note and leaves a lasting impact on your audience.

Why Conclusion is Important in Research Paper

The conclusion is the final chapter of your research paper journey, sealing the deal on all your hard work. After thoroughly laying out your main points and arguments in the body paragraphs, the conclusion gives you a chance to tie everything together into a neat, cohesive package.

More than just summarizing your key ideas, an effective conclusion shows readers the bigger picture of your research and why it matters. It highlights the significance of your findings , explains how your work contributes to the field, and points to potential future directions stemming from your study.

The conclusion is your last chance to leave a lasting impact and compel readers to seriously consider your perspective. With the right phrasing and tone, you can amplify the power of your work. Choose your words wisely, be persuasive yet diplomatic, and guide readers to walk away feeling satisfied by your reasoning and conclusions.

Approach the conclusion thoughtfully, reflect deeply on the larger meaning of your research, and craft impactful final sentences that linger in the reader’s mind. Wield your conclusion skillfully to make your research paper transformative and memorable. A powerful, thoughtful conclusion inspires action, sparks curiosity, and showcases the valuable insights you bring to the academic conversation.

How to Write Conclusion for a Research Paper

Crafting an effective conclusion in research paper requires thoughtful consideration and deliberate effort. After presenting your findings and analysis, the conclusion allows you to close your work with a flourish.

Begin by briefly summarizing the main points of your paper, provide a quick recap of your thesis, methodology, and key findings without repeating too much details from the body. Use this as an opportunity to reinforce your main argument and position within the field.

Next, highlight the significance and implications of your research. What new insights or perspectives does your work contribute? Discuss how your findings can inform future studies or practical applications. Convey why your research matters and how it moves the needle forward in your discipline.

Address any limitations of the current study and propose potential next steps that could be taken by you or other scholars to further the research. This shows readers you have critically considered ways to continue expanding knowledge in this area.

Finally, close with a memorable statement that captures the essence of your work and leaves a lasting impression. This could be an apt metaphor, a call to action, or a thought provoking question for readers to ponder. Choose words that will resonate with your audience and demonstrate the impact of your research.

With care and creativity, your conclusion can elevate your paper and cement your scholarly authority. Revisit often as you write to ensure your conclusion accomplishes its purpose, to convince readers of the value of your study and ignite further progress in your field.

What Not to Include in a Research Paper Conclusion

1. New Data: In a research paper conclusion, avoid presenting new data or evidence that wasn’t discussed earlier in the paper. It’s the time to summarize, analyze, or explain the significance of data already provided, not to introduce new material.

2. Irrelevant Details: The conclusion is not the spot for extraneous details not directly related to your research or its findings. Be focused and concise, tying up the paper neatly without going off-target.

3. Personal Opinions: Try not to include personal beliefs or subjective opinions unless your paper calls for it. Stick to empirical evidence, facts, and objective interpretation of your research.

4. Vague Summarization: While summarizing is the essence of a conclusion, too much of a broad or vague narrative should be avoided. Your conclusion shouldn’t be a generalization of the research but should specifically state your significant findings and their implications.

5. Overstating Results: No matter how exhilarating your research may be, don’t exaggerate its implications or general applications. Remember to acknowledge limitations or potential areas for future exploration.

6. Procrastinating: Refrain from leaving unresolved issues for future research. The conclusion is meant to tie up loose ends, not create more.

7. Repetition: While some reiteration is necessary, completely repeating the same phrases and points made previously can make your conclusion sound boring and redundant. Instead, try to look at your argument from a fresh, summarized perspective.

8. Apologies: Do not apologize or discredit your research efforts. Avoid phrases like, “This research was only” or “Although the study wasn’t able to prove”. A conclusion should confidently present your research results even if they’re unexpected or differ from your hypothesis.

9. Impractical Recommendations: While it’s often good to suggest directions for future research, don’t go overboard by proposing impractical or unachievable goals. Keep your recommendations relevant to your findings and within the realm of possibility.

10. Too Much Jargon: While it’s appropriate to use technical language throughout your research paper, remember the conclusion might be what a layman reads. Stick with a happy medium of professional lingo intermixed with understandable, plain language.

Also Check:   Conclusion for Internship Report

Conclusion in research Example

Research: Impact of Social Media Use on Adolescent Mental Health.

In conclusion, this study has demonstrated the significant impact of social media use on adolescent mental health. Our findings indicate that frequent social media use is associated with higher levels of anxiety and depression, particularly among girls. These results underscore the need for continued research in this area, as well as the development of interventions and strategies to promote healthy social media use among young people. By addressing this issue, we can help to ensure the well-being and success of the next generation.

Conclusion in Research Paper Example

Research: Impact of climate change on coral reefs in Florida.

In conclusion, the effect of climate change on Florida’s coral reefs presents a significant concern for the state’s ecosystem and economy. The data collected during this investigation reveal a direct correlation between rising ocean temperatures and coral bleaching events. This pattern has increased over the past decade, indicating that coral reefs’ health directly correlates with climate change effects.

Example Conclusion in Research

Research: The Influence of Social Media on Consumer Buying Behavior

Social media significantly shapes consumer buying behavior. Its power to influence is seen through peer opinions, online advertising, and brand communication. However, with the potential for misinformation, the reliability and quality of information are areas for further study. Despite these concerns, businesses leveraging social media can effectively boost their market reach and sales.

Research Paper Conclusion

Research: Impacts of Remote Work on Employee Productivity

Remote work has been found to notably enhance employee productivity. The elimination of commuting time, flexible scheduling, and comforting environment contribute to this increase. However, factors like home distractions and technological difficulties offer room for further research. Yet, integrating remote work can be a strategic pathway towards improved efficiency and workforce satisfaction.

These examples demonstrate techniques for crafting an effective conclusion in a research paper, providing your thesis with a powerful final statement. Now it is your turn to compose a strong concluding paragraph that summarizes your findings, reinforces your central argument, and leaves readers with a memorable takeaway.

Remember to restate your thesis without repeating it verbatim, highlight your main points without introducing new evidence, and end on a note that conveys the significance of your research. With a clear structure and purpose, proper grammar, and impactful writing, you can give your paper the persuasive conclusion it deserves.

Writing an effective conclusion takes practice, but by honing these skills you will elevate your academic writing to new heights. Use the strategies outlined here as a guide, believe in your capabilities, and soon you will be adept at concluding research papers powerfully. The final paragraph is your last chance to impress readers, so make it count!

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How to Write a Conclusion for a Research Paper

• 3-minute read
• 29th August 2023

If you’re writing a research paper, the conclusion is your opportunity to summarize your findings and leave a lasting impression on your readers. In this post, we’ll take you through how to write an effective conclusion for a research paper and how you can:

·   Reword your thesis statement

·   Highlight the significance of your research

·   Discuss limitations

·   Connect to the introduction

·   End with a thought-provoking statement

Rewording Your Thesis Statement

Begin your conclusion by restating your thesis statement in a way that is slightly different from the wording used in the introduction. Avoid presenting new information or evidence in your conclusion. Just summarize the main points and arguments of your essay and keep this part as concise as possible. Remember that you’ve already covered the in-depth analyses and investigations in the main body paragraphs of your essay, so it’s not necessary to restate these details in the conclusion.

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Highlighting the Significance of Your Research

The conclusion is a good place to emphasize the implications of your research . Avoid ambiguous or vague language such as “I think” or “maybe,” which could weaken your position. Clearly explain why your research is significant and how it contributes to the broader field of study.

Here’s an example from a (fictional) study on the impact of social media on mental health:

Discussing Limitations

Although it’s important to emphasize the significance of your study, you can also use the conclusion to briefly address any limitations you discovered while conducting your research, such as time constraints or a shortage of resources. Doing this demonstrates a balanced and honest approach to your research.

Connecting to the Introduction

In your conclusion, you can circle back to your introduction , perhaps by referring to a quote or anecdote you discussed earlier. If you end your paper on a similar note to how you began it, you will create a sense of cohesion for the reader and remind them of the meaning and significance of your research.

Ending With a Thought-Provoking Statement

Consider ending your paper with a thought-provoking and memorable statement that relates to the impact of your research questions or hypothesis. This statement can be a call to action, a philosophical question, or a prediction for the future (positive or negative). Here’s an example that uses the same topic as above (social media and mental health):

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How to write an excellent thesis conclusion [with examples]

Restate the thesis

Review or reiterate key points of your work, explain why your work is relevant, a take-away for the reader, more resources on writing thesis conclusions, frequently asked questions about writing an excellent thesis conclusion, related articles.

At this point in your writing, you have most likely finished your introduction and the body of your thesis, dissertation, or research paper . While this is a reason to celebrate, you should not underestimate the importance of your conclusion. The conclusion is the last thing that your reader will see, so it should be memorable.

A good conclusion will review the key points of the thesis and explain to the reader why the information is relevant, applicable, or related to the world as a whole. Make sure to dedicate enough of your writing time to the conclusion and do not put it off until the very last minute.

This article provides an effective technique for writing a conclusion adapted from Erika Eby’s The College Student's Guide to Writing a Good Research Paper: 101 Easy Tips & Tricks to Make Your Work Stand Out .

While the thesis introduction starts out with broad statements about the topic, and then narrows it down to the thesis statement , a thesis conclusion does the same in the opposite order.

• Restate the thesis.
• Review or reiterate key points of your work.
• Explain why your work is relevant.
• Include a core take-away message for the reader.

Tip: Don’t just copy and paste your thesis into your conclusion. Restate it in different words.

The best way to start a conclusion is simply by restating the thesis statement. That does not mean just copying and pasting it from the introduction, but putting it into different words.

You will need to change the structure and wording of it to avoid sounding repetitive. Also, be firm in your conclusion just as you were in the introduction. Try to avoid sounding apologetic by using phrases like "This paper has tried to show..."

The conclusion should address all the same parts as the thesis while making it clear that the reader has reached the end. You are telling the reader that your research is finished and what your findings are.

I have argued throughout this work that the point of critical mass for biopolitical immunity occurred during the Romantic period because of that era's unique combination of post-revolutionary politics and innovations in smallpox prevention. In particular, I demonstrated that the French Revolution and the discovery of vaccination in the 1790s triggered a reconsideration of the relationship between bodies and the state.

Tip: Try to reiterate points from your introduction in your thesis conclusion.

The next step is to review the main points of the thesis as a whole. Look back at the body of of your project and make a note of the key ideas. You can reword these ideas the same way you reworded your thesis statement and then incorporate that into the conclusion.

You can also repeat striking quotations or statistics, but do not use more than two. As the conclusion represents your own closing thoughts on the topic , it should mainly consist of your own words.

In addition, conclusions can contain recommendations to the reader or relevant questions that further the thesis. You should ask yourself:

• What you would ideally like to see your readers do in reaction to your paper?
• Do you want them to take a certain action or investigate further?
• Is there a bigger issue that your paper wants to draw attention to?

Also, try to reference your introduction in your conclusion. You have already taken a first step by restating your thesis. Now, check whether there are other key words, phrases or ideas that are mentioned in your introduction that fit into your conclusion. Connecting the introduction to the conclusion in this way will help readers feel satisfied.

I explored how Mary Wollstonecraft, in both her fiction and political writings, envisions an ideal medico-political state, and how other writers like William Wordsworth and Mary Shelley increasingly imagined the body politic literally, as an incorporated political collective made up of bodies whose immunity to political and medical ills was essential to a healthy state.

Tip: Make sure to explain why your thesis is relevant to your field of research.

Although you can encourage readers to question their opinions and reflect on your topic, do not leave loose ends. You should provide a sense of resolution and make sure your conclusion wraps up your argument. Make sure you explain why your thesis is relevant to your field of research and how your research intervenes within, or substantially revises, existing scholarly debates.

This project challenged conventional ideas about the relationship among Romanticism, medicine, and politics by reading the unfolding of Romantic literature and biopolitical immunity as mutual, co-productive processes. In doing so, this thesis revises the ways in which biopolitics has been theorized by insisting on the inherent connections between Romantic literature and the forms of biopower that characterize early modernity.

Tip: If you began your thesis with an anecdote or historical example, you may want to return to that in your conclusion.

End your conclusion with something memorable, such as:

• a call to action
• a recommendation
• a gesture towards future research
• a brief explanation of how the problem or idea you covered remains relevant

Ultimately, you want readers to feel more informed, or ready to act, as they read your conclusion.

Yet, the Romantic period is only the beginning of modern thought on immunity and biopolitics. Victorian writers, doctors, and politicians upheld the Romantic idea that a "healthy state" was a literal condition that could be achieved by combining politics and medicine, but augmented that idea through legislation and widespread public health measures. While many nineteenth-century efforts to improve citizens' health were successful, the fight against disease ultimately changed course in the twentieth century as global immunological threats such as SARS occupied public consciousness. Indeed, as subsequent public health events make apparent, biopolitical immunity persists as a viable concept for thinking about the relationship between medicine and politics in modernity.

Need more advice? Read our 5 additional tips on how to write a good thesis conclusion.

The conclusion is the last thing that your reader will see, so it should be memorable. To write a great thesis conclusion you should:

The basic content of a conclusion is to review the main points from the paper. This part represents your own closing thoughts on the topic. It should mainly consist of the outcome of the research in your own words.

The length of the conclusion will depend on the length of the whole thesis. Usually, a conclusion should be around 5-7% of the overall word count.

End your conclusion with something memorable, such as a question, warning, or call to action. Depending on the topic, you can also end with a recommendation.

In Open Access: Theses and Dissertations you can find thousands of completed works. Take a look at any of the theses or dissertations for real-life examples of conclusions that were already approved.

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• How to conclude an essay | Interactive example

How to Conclude an Essay | Interactive Example

Published on January 24, 2019 by Shona McCombes . Revised on July 23, 2023.

The conclusion is the final paragraph of your essay . A strong conclusion aims to:

• Tie together the essay’s main points
• Show why your argument matters
• Leave the reader with a strong impression

Your conclusion should give a sense of closure and completion to your argument, but also show what new questions or possibilities it has opened up.

This conclusion is taken from our annotated essay example , which discusses the history of the Braille system. Hover over each part to see why it’s effective.

Braille paved the way for dramatic cultural changes in the way blind people were treated and the opportunities available to them. Louis Braille’s innovation was to reimagine existing reading systems from a blind perspective, and the success of this invention required sighted teachers to adapt to their students’ reality instead of the other way around. In this sense, Braille helped drive broader social changes in the status of blindness. New accessibility tools provide practical advantages to those who need them, but they can also change the perspectives and attitudes of those who do not.

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Table of contents

Step 1: return to your thesis, step 2: review your main points, step 3: show why it matters, what shouldn’t go in the conclusion, more examples of essay conclusions, other interesting articles, frequently asked questions about writing an essay conclusion.

To begin your conclusion, signal that the essay is coming to an end by returning to your overall argument.

Don’t just repeat your thesis statement —instead, try to rephrase your argument in a way that shows how it has been developed since the introduction.

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Next, remind the reader of the main points that you used to support your argument.

Avoid simply summarizing each paragraph or repeating each point in order; try to bring your points together in a way that makes the connections between them clear. The conclusion is your final chance to show how all the paragraphs of your essay add up to a coherent whole.

To wrap up your conclusion, zoom out to a broader view of the topic and consider the implications of your argument. For example:

• Does it contribute a new understanding of your topic?
• Does it raise new questions for future study?
• Does it lead to practical suggestions or predictions?
• Can it be applied to different contexts?
• Can it be connected to a broader debate or theme?

Whatever your essay is about, the conclusion should aim to emphasize the significance of your argument, whether that’s within your academic subject or in the wider world.

Try to end with a strong, decisive sentence, leaving the reader with a lingering sense of interest in your topic.

The easiest way to improve your conclusion is to eliminate these common mistakes.

Don’t include new evidence

Any evidence or analysis that is essential to supporting your thesis statement should appear in the main body of the essay.

The conclusion might include minor pieces of new information—for example, a sentence or two discussing broader implications, or a quotation that nicely summarizes your central point. But it shouldn’t introduce any major new sources or ideas that need further explanation to understand.

Don’t use “concluding phrases”

Avoid using obvious stock phrases to tell the reader what you’re doing:

• “In conclusion…”
• “To sum up…”

These phrases aren’t forbidden, but they can make your writing sound weak. By returning to your main argument, it will quickly become clear that you are concluding the essay—you shouldn’t have to spell it out.

Don’t undermine your argument

Avoid using apologetic phrases that sound uncertain or confused:

• “This is just one approach among many.”
• “There are good arguments on both sides of this issue.”
• “There is no clear answer to this problem.”

Even if your essay has explored different points of view, your own position should be clear. There may be many possible approaches to the topic, but you want to leave the reader convinced that yours is the best one!

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• Literary analysis

This conclusion is taken from an argumentative essay about the internet’s impact on education. It acknowledges the opposing arguments while taking a clear, decisive position.

The internet has had a major positive impact on the world of education; occasional pitfalls aside, its value is evident in numerous applications. The future of teaching lies in the possibilities the internet opens up for communication, research, and interactivity. As the popularity of distance learning shows, students value the flexibility and accessibility offered by digital education, and educators should fully embrace these advantages. The internet’s dangers, real and imaginary, have been documented exhaustively by skeptics, but the internet is here to stay; it is time to focus seriously on its potential for good.

This conclusion is taken from a short expository essay that explains the invention of the printing press and its effects on European society. It focuses on giving a clear, concise overview of what was covered in the essay.

The invention of the printing press was important not only in terms of its immediate cultural and economic effects, but also in terms of its major impact on politics and religion across Europe. In the century following the invention of the printing press, the relatively stationary intellectual atmosphere of the Middle Ages gave way to the social upheavals of the Reformation and the Renaissance. A single technological innovation had contributed to the total reshaping of the continent.

This conclusion is taken from a literary analysis essay about Mary Shelley’s Frankenstein . It summarizes what the essay’s analysis achieved and emphasizes its originality.

By tracing the depiction of Frankenstein through the novel’s three volumes, I have demonstrated how the narrative structure shifts our perception of the character. While the Frankenstein of the first volume is depicted as having innocent intentions, the second and third volumes—first in the creature’s accusatory voice, and then in his own voice—increasingly undermine him, causing him to appear alternately ridiculous and vindictive. Far from the one-dimensional villain he is often taken to be, the character of Frankenstein is compelling because of the dynamic narrative frame in which he is placed. In this frame, Frankenstein’s narrative self-presentation responds to the images of him we see from others’ perspectives. This conclusion sheds new light on the novel, foregrounding Shelley’s unique layering of narrative perspectives and its importance for the depiction of character.

If you want to know more about AI tools , college essays , or fallacies make sure to check out some of our other articles with explanations and examples or go directly to our tools!

• Ad hominem fallacy
• Post hoc fallacy
• Appeal to authority fallacy
• False cause fallacy
• Sunk cost fallacy

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Your essay’s conclusion should contain:

• A rephrased version of your overall thesis
• A brief review of the key points you made in the main body
• An indication of why your argument matters

The conclusion may also reflect on the broader implications of your argument, showing how your ideas could applied to other contexts or debates.

For a stronger conclusion paragraph, avoid including:

• Important evidence or analysis that wasn’t mentioned in the main body
• Generic concluding phrases (e.g. “In conclusion…”)
• Weak statements that undermine your argument (e.g. “There are good points on both sides of this issue.”)

Your conclusion should leave the reader with a strong, decisive impression of your work.

The conclusion paragraph of an essay is usually shorter than the introduction . As a rule, it shouldn’t take up more than 10–15% of the text.

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The conclusion is intended to help the reader understand why your research should matter to them after they have finished reading the paper. A conclusion is not merely a summary of the main topics covered or a re-statement of your research problem, but a synthesis of key points derived from the findings of your study and, if applicable based on your analysis, explain new areas for future research. For most college-level research papers, two or three well-developed paragraphs is sufficient for a conclusion, although in some cases, more paragraphs may be required in describing the key findings and highlighting their significance.

Conclusions. The Writing Center. University of North Carolina; Conclusions. The Writing Lab and The OWL. Purdue University.

Importance of a Good Conclusion

A well-written conclusion provides important opportunities to demonstrate to the reader your understanding of the research problem. These include:

• Presenting the last word on the issues you raised in your paper . Just as the introduction gives a first impression to your reader, the conclusion offers a chance to leave a lasting impression. Do this, for example, by highlighting key findings in your analysis that advance new understanding about the research problem, that are unusual or unexpected, or that have important implications applied to practice.
• Summarizing your thoughts and conveying the larger significance of your study . The conclusion is an opportunity to succinctly re-emphasize  your answer to the "So What?" question by placing the study within the context of how your research advances past studies about the topic.
• Identifying how a gap in the literature has been addressed . The conclusion can be where you describe how a previously identified gap in the literature [first identified in your literature review section] has been addressed by your research and why this contribution is significant.
• Demonstrating the importance of your ideas . Don't be shy. The conclusion offers an opportunity to elaborate on the impact and significance of your findings. This is particularly important if your study approached examining the research problem from an unusual or innovative perspective.
• Introducing possible new or expanded ways of thinking about the research problem . This does not refer to introducing new information [which should be avoided], but to offer new insight and creative approaches for framing or contextualizing the research problem based on the results of your study.

Bunton, David. “The Structure of PhD Conclusion Chapters.” Journal of English for Academic Purposes 4 (July 2005): 207–224; Conclusions. The Writing Center. University of North Carolina; Kretchmer, Paul. Twelve Steps to Writing an Effective Conclusion. San Francisco Edit, 2003-2008; Conclusions. The Writing Lab and The OWL. Purdue University; Assan, Joseph. "Writing the Conclusion Chapter: The Good, the Bad and the Missing." Liverpool: Development Studies Association (2009): 1-8.

Structure and Writing Style

I.  General Rules

The general function of your paper's conclusion is to restate the main argument . It reminds the reader of your main argument(s) strengths and reiterates the most important evidence supporting those argument(s). Do this by clearly summarizing the context, background, and the necessity of examining the research problem in relation to an issue, controversy, or a gap found in the literature. However, make sure that your conclusion is not simply a repetitive summary of the findings. This reduces the impact of the argument(s) you have developed in your paper.

When writing the conclusion to your paper, follow these general rules:

• Present your conclusions in clear, concise language. Re-state the purpose of your study, then describe how your findings differ or support those of other studies and why [i.e., describe what were the unique, new, or crucial contributions your study made to the overall research about your topic].
• Do not simply reiterate your findings or the discussion of your results. Provide a synthesis of arguments presented in the paper to show how these converge to address the research problem and the overall objectives of your study.
• Indicate opportunities for future research if you haven't already done so in the discussion section of your paper. Highlighting the need for further research provides the reader with evidence that you have an in-depth awareness of the research problem but that further analysis should take place beyond the scope of your investigation.

Consider the following points to help ensure your conclusion is presented well:

• If the argument or purpose of your paper is complex, you may need to summarize the argument for your reader.
• If, prior to your conclusion, you have not yet explained the significance of your findings or if you are proceeding inductively, use the end of your paper to describe your main points and explain their significance.
• Move from a detailed to a general level of consideration that returns the topic to the context provided by the introduction or within a new context that emerges from the data [this is opposite of the introduction, which begins with general discussion of the context and ends with a detailed description of the research problem]. 

The conclusion also provides a place for you to persuasively and succinctly restate the research problem, given that the reader has now been presented with all the information about the topic . Depending on the discipline you are writing in, the concluding paragraph may contain your reflections on the evidence presented. However, the nature of being introspective about the research you have conducted will depend on the topic and whether your professor wants you to express your observations in this way. If asked to think introspectively about the topic, do not delve into idle speculation. Being introspective means looking within yourself as an author to try and understand an issue more deeply, not to guess at possible outcomes or make up scenarios not supported by the evidence.

II.  Developing a Compelling Conclusion

Although an effective conclusion needs to be clear and succinct, it does not need to be written passively or lack a compelling narrative. Strategies to help you move beyond merely summarizing the key points of your research paper may include any of the following:

• If your paper addresses a critical, contemporary problem, warn readers of the possible consequences of not attending to the problem proactively based on the evidence presented in your study.
• Recommend a specific course or courses of action that, if adopted, could address a specific problem in practice or in the development of new knowledge leading to positive change.
• Cite a relevant quotation or expert opinion already noted in your paper in order to lend authority and support to the conclusion(s) you have reached [a good source would be from a source cited in your literature review].
• Explain the consequences of your research in a way that elicits action or demonstrates urgency in seeking change.
• Restate a key statistic, fact, or visual image to emphasize the most important finding of your paper.
• If your discipline encourages personal reflection, illustrate your concluding point by drawing from your own life experiences.
• Return to an anecdote, an example, or a quotation that you presented in your introduction, but add further insight derived from the findings of your study; use your interpretation of results from your study to recast it in new or important ways.
• Provide a "take-home" message in the form of a succinct, declarative statement that you want the reader to remember about your study.

III. Problems to Avoid

Failure to be concise Your conclusion section should be concise and to the point. Conclusions that are too lengthy often have unnecessary information in them. The conclusion is not the place for details about your methodology or results. Although you should give a summary of what was learned from your research, this summary should be relatively brief, since the emphasis in the conclusion is on the implications, evaluations, insights, and other forms of analysis that you make. Strategies for writing concisely can be found here .

Failure to comment on larger, more significant issues In the introduction, your task was to move from the general [topic studied within the field of study] to the specific [the research problem]. However, in the conclusion, your task is to move the discussion from specific [your research problem] back to a general discussion framed around the implications and significance of your findings [i.e., how your research contributes new understanding or fills an important gap in the literature]. In short, the conclusion is where you should place your research within a larger context [visualize the structure of your paper as an hourglass--start with a broad introduction and review of the literature, move to the specific method of analysis and the discussion, conclude with a broad summary of the study's implications and significance].

Failure to reveal problems and negative results Negative aspects of the research process should never be ignored. These are problems, deficiencies, or challenges encountered during your study. They should be summarized as a way of qualifying your overall conclusions. If you encountered negative or unintended results [i.e., findings that are validated outside the research context in which they were generated], you must report them in the results section and discuss their implications in the discussion section of your paper. In the conclusion, use negative or surprising results as an opportunity to explain their possible significance and/or how they may form the basis for future research.

Failure to provide a clear summary of what was learned In order to discuss how your research fits within your field of study [and possibly the world at large], you need to summarize briefly and succinctly how it contributes to new knowledge or a new understanding about the research problem. This element of your conclusion may be only a few sentences long, but it often represents the key takeaway for your reader.

Failure to match the objectives of your research Often research objectives in the social and behavioral sciences change while the research is being carried out due to unforeseen factors or unanticipated variables. This is not a problem unless you forget to go back and refine the original objectives in your introduction. As these changes emerge they must be documented so that they accurately reflect what you were trying to accomplish in your research [not what you thought you might accomplish when you began].

Resist the urge to apologize If you've immersed yourself in studying the research problem, you presumably should know a good deal about it [perhaps even more than your professor!]. Nevertheless, by the time you have finished writing, you may be having some doubts about what you have produced. Repress those doubts! Don't undermine your authority as a researcher by saying something like, "This is just one approach to examining this problem; there may be other, much better approaches that...." The overall tone of your conclusion should convey confidence to the reader concerning the validity and realiability of your research.

Assan, Joseph. "Writing the Conclusion Chapter: The Good, the Bad and the Missing." Liverpool: Development Studies Association (2009): 1-8; Concluding Paragraphs. College Writing Center at Meramec. St. Louis Community College; Conclusions. The Writing Center. University of North Carolina; Conclusions. The Writing Lab and The OWL. Purdue University; Freedman, Leora  and Jerry Plotnick. Introductions and Conclusions. The Lab Report. University College Writing Centre. University of Toronto; Leibensperger, Summer. Draft Your Conclusion. Academic Center, the University of Houston-Victoria, 2003; Make Your Last Words Count. The Writer’s Handbook. Writing Center. University of Wisconsin Madison; Miquel, Fuster-Marquez and Carmen Gregori-Signes. “Chapter Six: ‘Last but Not Least:’ Writing the Conclusion of Your Paper.” In Writing an Applied Linguistics Thesis or Dissertation: A Guide to Presenting Empirical Research . John Bitchener, editor. (Basingstoke,UK: Palgrave Macmillan, 2010), pp. 93-105; Tips for Writing a Good Conclusion. Writing@CSU. Colorado State University; Kretchmer, Paul. Twelve Steps to Writing an Effective Conclusion. San Francisco Edit, 2003-2008; Writing Conclusions. Writing Tutorial Services, Center for Innovative Teaching and Learning. Indiana University; Writing: Considering Structure and Organization. Institute for Writing Rhetoric. Dartmouth College.

Writing Tip

Don't Belabor the Obvious!

Avoid phrases like "in conclusion...," "in summary...," or "in closing...." These phrases can be useful, even welcome, in oral presentations. But readers can see by the tell-tale section heading and number of pages remaining that they are reaching the end of your paper. You'll irritate your readers if you belabor the obvious.

Assan, Joseph. "Writing the Conclusion Chapter: The Good, the Bad and the Missing." Liverpool: Development Studies Association (2009): 1-8.

Another Writing Tip

New Insight, Not New Information!

Don't surprise the reader with new information in your conclusion that was never referenced anywhere else in the paper. This is why the conclusion rarely has citations to sources that haven't been referenced elsewhere in your paper. If you have new information to present, add it to the discussion or other appropriate section of the paper. Note that, although no new information is introduced, the conclusion, along with the discussion section, is where you offer your most "original" contributions in the paper; the conclusion is where you describe the value of your research, demonstrate that you understand the material that you have presented, and position your findings within the larger context of scholarship on the topic, including describing how your research contributes new insights to that scholarship.

Assan, Joseph. "Writing the Conclusion Chapter: The Good, the Bad and the Missing." Liverpool: Development Studies Association (2009): 1-8; Conclusions. The Writing Center. University of North Carolina.

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How to Write a Conclusion for a Research Paper

Last Updated: July 8, 2024 Approved

This article was co-authored by Christopher Taylor, PhD . Christopher Taylor is an Adjunct Assistant Professor of English at Austin Community College in Texas. He received his PhD in English Literature and Medieval Studies from the University of Texas at Austin in 2014. wikiHow marks an article as reader-approved once it receives enough positive feedback. This article received 43 testimonials and 83% of readers who voted found it helpful, earning it our reader-approved status. This article has been viewed 2,263,467 times.

The conclusion of a research paper needs to summarize the content and purpose of the paper without seeming too wooden or dry. Every basic conclusion must share several key elements, but there are also several tactics you can play around with to craft a more effective conclusion and several you should avoid to prevent yourself from weakening your paper's conclusion. Here are some writing tips to keep in mind when creating a conclusion for your next research paper.

Sample Conclusions

Writing a basic conclusion.

• Do not spend a great amount of time or space restating your topic.
• A good research paper will make the importance of your topic apparent, so you do not need to write an elaborate defense of your topic in the conclusion.
• Usually a single sentence is all you need to restate your topic.
• An example would be if you were writing a paper on the epidemiology of infectious disease, you might say something like "Tuberculosis is a widespread infectious disease that affects millions of people worldwide every year."
• Yet another example from the humanities would be a paper about the Italian Renaissance: "The Italian Renaissance was an explosion of art and ideas centered around artists, writers, and thinkers in Florence."

• A thesis is a narrowed, focused view on the topic at hand.
• This statement should be rephrased from the thesis you included in your introduction. It should not be identical or too similar to the sentence you originally used.
• Try re-wording your thesis statement in a way that complements your summary of the topic of your paper in your first sentence of your conclusion.
• An example of a good thesis statement, going back to the paper on tuberculosis, would be "Tuberculosis is a widespread disease that affects millions of people worldwide every year. Due to the alarming rate of the spread of tuberculosis, particularly in poor countries, medical professionals are implementing new strategies for the diagnosis, treatment, and containment of this disease ."

• A good way to go about this is to re-read the topic sentence of each major paragraph or section in the body of your paper.
• Find a way to briefly restate each point mentioned in each topic sentence in your conclusion. Do not repeat any of the supporting details used within your body paragraphs.
• Under most circumstances, you should avoid writing new information in your conclusion. This is especially true if the information is vital to the argument or research presented in your paper.
• For example, in the TB paper you could summarize the information. "Tuberculosis is a widespread disease that affects millions of people worldwide. Due to the alarming rate of the spread of tuberculosis, particularly in poor countries, medical professionals are implementing new strategies for the diagnosis, treatment, and containment of this disease. In developing countries, such as those in Africa and Southeast Asia, the rate of TB infections is soaring. Crowded conditions, poor sanitation, and lack of access to medical care are all compounding factors in the spread of the disease. Medical experts, such as those from the World Health Organization are now starting campaigns to go into communities in developing countries and provide diagnostic testing and treatments. However, the treatments for TB are very harsh and have many side effects. This leads to patient non-compliance and spread of multi-drug resistant strains of the disease."

• Note that this is not needed for all research papers.
• If you already fully explained what the points in your paper mean or why they are significant, you do not need to go into them in much detail in your conclusion. Simply restating your thesis or the significance of your topic should suffice.
• It is always best practice to address important issues and fully explain your points in the body of your paper. The point of a conclusion to a research paper is to summarize your argument for the reader and, perhaps, to call the reader to action if needed.

• Note that a call for action is not essential to all conclusions. A research paper on literary criticism, for instance, is less likely to need a call for action than a paper on the effect that television has on toddlers and young children.
• A paper that is more likely to call readers to action is one that addresses a public or scientific need. Let's go back to our example of tuberculosis. This is a very serious disease that is spreading quickly and with antibiotic-resistant forms.
• A call to action in this research paper would be a follow-up statement that might be along the lines of "Despite new efforts to diagnose and contain the disease, more research is needed to develop new antibiotics that will treat the most resistant strains of tuberculosis and ease the side effects of current treatments."

• For example, if you are writing a history paper, then you might discuss how the historical topic you discussed matters today. If you are writing about a foreign country, then you might use the conclusion to discuss how the information you shared may help readers understand their own country.

Making Your Conclusion as Effective as Possible

• Since this sort of conclusion is so basic, you must aim to synthesize the information rather than merely summarizing it.
• Instead of merely repeating things you already said, rephrase your thesis and supporting points in a way that ties them all together.
• By doing so, you make your research paper seem like a "complete thought" rather than a collection of random and vaguely related ideas.

• Ask a question in your introduction. In your conclusion, restate the question and provide a direct answer.
• Write an anecdote or story in your introduction but do not share the ending. Instead, write the conclusion to the anecdote in the conclusion of your paper.
• For example, if you wanted to get more creative and put a more humanistic spin on a paper on tuberculosis, you might start your introduction with a story about a person with the disease, and refer to that story in your conclusion. For example, you could say something like this before you re-state your thesis in your conclusion: "Patient X was unable to complete the treatment for tuberculosis due to severe side effects and unfortunately succumbed to the disease."
• Use the same concepts and images introduced in your introduction in your conclusion. The images may or may not appear at other points throughout the research paper.

• Include enough information about your topic to back the statement up but do not get too carried away with excess detail.
• If your research did not provide you with a clear-cut answer to a question posed in your thesis, do not be afraid to indicate as much.
• Restate your initial hypothesis and indicate whether you still believe it or if the research you performed has begun swaying your opinion.
• Indicate that an answer may still exist and that further research could shed more light on the topic at hand.

• This may not be appropriate for all types of research papers. Most research papers, such as one on effective treatment for diseases, will have the information to make the case for a particular argument already in the paper.
• A good example of a paper that might ask a question of the reader in the ending is one about a social issue, such as poverty or government policy.
• Ask a question that will directly get at the heart or purpose of the paper. This question is often the same question, or some version of it, that you may have started with when you began your research.
• Make sure that the question can be answered by the evidence presented in your paper.
• If desired you can briefly summarize the answer after stating the question. You could also leave the question hanging for the reader to answer, though.

• Even without a call to action, you can still make a recommendation to your reader.
• For instance, if you are writing about a topic like third-world poverty, you can various ways for the reader to assist in the problem without necessarily calling for more research.
• Another example would be, in a paper about treatment for drug-resistant tuberculosis, you could suggest donating to the World Health Organization or research foundations that are developing new treatments for the disease.

Avoiding Common Pitfalls

• These sayings usually sound stiff, unnatural, or trite when used in writing.
• Moreover, using a phrase like "in conclusion" to begin your conclusion is a little too straightforward and tends to lead to a weak conclusion. A strong conclusion can stand on its own without being labeled as such.

• Always state the main argument or thesis in the introduction. A research paper is an analytical discussion of an academic topic, not a mystery novel.
• A good, effective research paper will allow your reader to follow your main argument from start to finish.
• This is why it is best practice to start your paper with an introduction that states your main argument and to end the paper with a conclusion that re-states your thesis for re-iteration.

• All significant information should be introduced in the body of the paper.
• Supporting evidence expands the topic of your paper by making it appear more detailed. A conclusion should narrow the topic to a more general point.
• A conclusion should only summarize what you have already stated in the body of your paper.
• You may suggest further research or a call to action, but you should not bring in any new evidence or facts in the conclusion.

• Most often, a shift in tone occurs when a research paper with an academic tone gives an emotional or sentimental conclusion.
• Even if the topic of the paper is of personal significance for you, you should not indicate as much in your paper.
• If you want to give your paper a more humanistic slant, you could start and end your paper with a story or anecdote that would give your topic more personal meaning to the reader.
• This tone should be consistent throughout the paper, however.

• Apologetic statements include phrases like "I may not be an expert" or "This is only my opinion."
• Statements like this can usually be avoided by refraining from writing in the first-person.
• Avoid any statements in the first-person. First-person is generally considered to be informal and does not fit with the formal tone of a research paper.

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• ↑ http://owl.english.purdue.edu/owl/resource/724/04/
• ↑ http://www.crlsresearchguide.org/18_Writing_Conclusion.asp
• ↑ http://writing.wisc.edu/Handbook/PlanResearchPaper.html#conclusion
• ↑ http://writingcenter.unc.edu/handouts/conclusions/

About This Article

To write a conclusion for a research paper, start by restating your thesis statement to remind your readers what your main topic is and bring everything full circle. Then, briefly summarize all of the main points you made throughout your paper, which will help remind your readers of everything they learned. You might also want to include a call to action if you think more research or work needs to be done on your topic by writing something like, "Despite efforts to contain the disease, more research is needed to develop antibiotics." Finally, end your conclusion by explaining the broader context of your topic and why your readers should care about it, which will help them understand why your topic is relevant and important. For tips from our Academic co-author, like how to avoid common pitfalls when writing your conclusion, scroll down! Did this summary help you? Yes No

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Writing a Research Paper Conclusion - Step-by-Step Guide

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Finishing a research paper feels great, but getting to the end—especially the conclusion—can be a bit tricky. 

People often wonder, "How do I wrap up my findings nicely?" or "What tone should I use in the conclusion?" 

If you're dealing with these questions, you're not alone! Many researchers find writing a good conclusion a bit challenging since it's a crucial part that is meant to leave a strong impression on your readers.

No need to worry! 

In this guide, we'll show you how to write a conclusion that not only ties up your research paper neatly but also leaves a strong impression. We'll cover everything from summarizing effectively to creating the right feeling. 

So, let’s get started. 

• 1. What is a Research Paper Conclusion?
• 2. How to Write a Research Paper Conclusion: 7 Steps
• 3. Research Paper Conclusion Examples
• 4. Things to Avoid While Writing the Research Paper Conclusion

What is a Research Paper Conclusion?

A research paper conclusion is like the final chapter of your paper. It's where you bring everything together and leave a lasting impression on your readers. 

In simple terms, it's the last part where you sum up what you found during your research and explain why it matters. 

The conclusion isn't just a summary; it's a chance to make your research memorable and show its importance.

Types of Research Paper Conclusions

When it comes to writing the conclusion of your research paper, there isn't a one-size-fits-all approach. Different types of research papers call for different types of conclusions. Here are some common types:

• Summarizing Conclusion

This type recaps the key points and findings of your research. It's like giving your readers a quick overview of what you discovered without introducing new information. Summarizing conclusions works well for straightforward research papers.

• Reflective Conclusion

A reflective conclusion allows you to share your personal thoughts on the research process, challenges faced, and lessons learned. It adds a human touch to your paper, giving readers insight into your journey as a researcher.

• Open-ended Conclusion

Some research papers benefit from an open-ended conclusion that leaves room for further exploration. This type invites readers to think critically, ask questions, or even conduct additional research on the same topic.

How to Write a Research Paper Conclusion: 7 Steps

Writing an effective conclusion for your research paper involves more than just summarizing your findings. Follow these six essential steps to ensure your conclusion leaves a lasting impact:

Step 1: Restate the Research Problem

Start wrapping up your paper by going back to the main research question or issue you were investigating. 

Remind your readers about what you were trying to find out or understand. This gives your conclusion a clear connection to the original goal of your research, helping readers see the bigger picture.

Step 2: Revisit Your Thesis Statement

Go back to the main idea or argument you had in your paper—this is called your thesis statement. Double-check that your conclusion matches and supports what you wanted to prove or talk about in the beginning. 

This step is important because it keeps your conclusion connected to the main point of your research, making everything fit together nicely.

Step 3: Summarize Key Points

Give a short and clear recap of the most important things you found in your research. Keep it simple and stick to what you've already talked about—don't bring in new details now. 

The goal is to remind your readers of the important stuff you covered earlier. This helps to underline why your research is important and what you want them to take away from it.

Step 4: Discuss the Implications

Address the broader implications of your research. Explain why your findings matter and how they contribute to the existing body of knowledge in your field. 

Discuss the practical applications of your research and highlight any potential areas for further exploration.

Step 5: Connect with the Introduction

Create a seamless connection between your conclusion and the introduction. Referencing key elements from the introduction helps to create a cohesive narrative for your paper. 

This connection gives your research a sense of completeness and unity.

Step 6: Consider the "So What?" Factor

Ask yourself the question, "So what?" Why should readers care about your research? Clearly articulate the significance of your findings and their relevance to the broader academic or real-world context. 

Demonstrating the impact of your research adds depth to your conclusion.

Step 7: End with a Strong Closing Statement:

Conclude your research paper with a memorable closing statement. This could be a thought-provoking reflection, a call to action, or a suggestion for future research.

A strong closing leaves a lasting impression on your readers and emphasizes the importance of your work.

Research Paper Conclusion Examples

When it comes to writing a conclusion for your research paper, examining examples can offer valuable insights. Let’s take a look at this comprehensive example given below:

Still wondering how to write the conclusion for your research paper? Check out these examples for better understanding:

Conclusion For A Research Paper APA

Conclusion For A Research Paper Example Pdf

Conclusion For A Research Paper Pdf

Conclusion For A Research Paper Middle School

Conclusion For A Scientific Paper

Conclusion For A Research Paper Sample

Things to Avoid While Writing the Research Paper Conclusion

While crafting a conclusion for your research paper, it's crucial to steer clear of common pitfalls that can diminish the impact of your final remarks. 

Here are some things to avoid:

• Repetition: Avoid rehashing the exact language used in the introduction or body of your paper. A conclusion should summarize key points without duplicating content.
• Introducing New Information: Resist the temptation to introduce new ideas or data in the conclusion. This section is for summarizing existing content and reinforcing key findings.
• Overly Complex Language: Keep your conclusion clear and accessible. Avoid introducing overly complex or technical language that might confuse your readers.
• Lack of Connection to Introduction: Ensure that your conclusion ties back to the introduction. Failing to connect these sections can make your paper feel disjointed.
• Vague Statements: Steer clear of vague statements that lack substance. Clearly articulate the significance of your findings and their broader implications.
• Apologies or Excuses: Avoid including apologies or excuses for limitations in your research. While acknowledging limitations is important, the conclusion is not the place to dwell on them.
• New Arguments or Debates: The conclusion is not the space to introduce new debates or arguments. Keep the focus on summarizing your research and its implications.
• Abrupt Endings: A conclusion should not end abruptly. Instead, provide a thoughtful and well-rounded closing statement about the results of your study.

To sum it up, we've gone through important steps to make your research paper conclusion strong. We covered things like going back to your main question, talking about the most important points, and thinking about why your research matters in the real world.

Remember, a good ending is more than just a summary; it captures the heart of your research and answers the big "So what?" question. 

Remember, don't say the same things too much, don't add new details at the end, and keep your language simple!

If you ever need help with your academic writing, MyPerfectWords.com is here for you. Our expert writers are committed to helping you excel in your research papers and beyond. 

Take the next step towards academic success with MyPerfectWords.com, and hire our legit essay writing service  today!

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Dr. Barbara is a highly experienced writer and author who holds a Ph.D. degree in public health from an Ivy League school. She has worked in the medical field for many years, conducting extensive research on various health topics. Her writing has been featured in several top-tier publications.

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How to Write a Conclusion for a Research Paper

When you're wrapping up a research paper, the conclusion is like the grand finale of a fireworks show – it's your chance to leave a lasting impression. In this article, we'll break down the steps to help you write a winning research paper conclusion that not only recaps your main points but also ties everything together. Consider it the "So what?" moment – why should people care about your research? Our professional essay writers will guide you through making your conclusion strong, clear, and something that sticks with your readers long after they've put down your paper. So, let's dive in and ensure your research ends on a high note!

What Is a Conclusion in a Research Paper

In a research paper, the conclusion serves as the final segment, where you summarize the main points and findings of your study. It's not just a repetition of what you've already said but rather a chance to tie everything together and highlight the significance of your research. As you learn how to start a research paper , a good conclusion also often discusses the implications of your findings, suggests potential areas for further research, and leaves the reader with a lasting impression of the importance and relevance of your work in the broader context of the field. Essentially, it's your last opportunity to make a strong impact and leave your readers with a clear understanding of the significance of your research. Here’s a research paper conclusion example:

In conclusion, this research paper has navigated the intricacies of sustainable urban development, shedding light on the pivotal role of community engagement and innovative planning strategies. Through applying qualitative and quantitative research methods, we've uncovered valuable insights into the challenges and opportunities inherent in fostering environmentally friendly urban spaces. The implications of these findings extend beyond the confines of this study, emphasizing the imperative for continued exploration in the realms of urban planning and environmental sustainability. By emphasizing both the practical applications and theoretical contributions, this research underscores the significance of community involvement and forward-thinking strategies in shaping the future of urban landscapes. As cities evolve, incorporating these insights into planning and development practices will create resilient and harmonious urban environments.

Conclusion Outline for Research Paper

This outline for a research paper conclusion provides a structured framework to ensure that your ending effectively summarizes the key elements of your research paper and leaves a lasting impression on your readers. Adjust the content based on the specific requirements and focus of your research.

Restate the Thesis Statement

• Briefly restate the main thesis or research question.
• Emphasize the core objective or purpose of the study.

Summarize Key Findings

• Recap the main points and key findings from each section of the paper.
• Provide a concise overview of the research journey.

Discuss Implications

• Explore the broader implications of the research findings.
• Discuss how the results contribute to the existing body of knowledge in the field.

Address Limitations

• Acknowledge any limitations or constraints encountered during the research process.
• Explain how these limitations may impact the interpretation of the findings.

Suggest Areas for Future Research

• Propose potential directions for future studies related to the topic.
• Identify gaps in the current research that warrant further exploration.

Reaffirm Significance

• Reaffirm the importance and relevance of the research in the broader context.
• Highlight the practical applications or real-world implications of the study.

Concluding Statement

• Craft a strong, memorable closing statement that leaves a lasting impression.
• Sum up the overall impact of the research and its potential contribution to the field.

Study the full guide on how to make a research paper outline here, which will also specify the conclusion writing specifics to improve your general prowess.

Tips on How to Make a Conclusion in Research

Here are key considerations regarding a conclusion for research paper to not only recap the primary ideas in your work but also delve deeper to earn a higher grade:

• Provide a concise recap of your main research outcomes.
• Remind readers of your research goals and their accomplishments.
• Stick to summarizing existing content; refrain from adding new details.
• Emphasize why your research matters and its broader implications.
• Clearly explain the practical or theoretical impact of your findings.
• Prompt readers to reflect on how your research influences their perspective.
• Briefly discuss the robustness of your research methods.
• End with a suggestion for future research or a practical application.
• Transparently address any constraints or biases in your study.
• End on a powerful note, leaving a memorable impression on your readers.

For your inspiration, we’ve also prepared this research proposal example APA , which dwells on another important aspect of research writing.

How to Write a Research Paper Conclusion

As you finish your research paper, the conclusion takes center stage. In this section, we've got five practical tips for writing a conclusion for a research paper. We'll guide you through summarizing your key findings, revisiting your research goals, discussing the bigger picture, addressing any limitations, and ending on a powerful note. Think of it as your roadmap to creating a conclusion that not only wraps up your research but also leaves a lasting impact on your readers. Let's dive in and make sure your conclusion stands out for all the right reasons!

Synthesize Core Discoveries. Initiate your conclusion by synthesizing the essential discoveries of your research. Offer a succinct recapitulation of the primary points and outcomes you have elucidated in your paper. This aids in reinforcing the gravity of your work and reiterates the pivotal information you have presented.

Revisit Research Objectives. Revisit the research objectives or questions you outlined at the beginning of your paper. Assess whether you have successfully addressed these objectives and if your findings align with the initial goals of your research. This reflection helps tie your conclusion back to the purpose of your study.

Discuss Implications and Contributions. Discuss the broader implications of your research and its potential contributions to the field. Consider how your findings might impact future research, applications, or understanding of the subject matter. This demonstrates the significance of your work and places it within a larger context.

Address Limitations and Future Research. Acknowledge any limitations in your study, such as constraints in data collection or potential biases. Briefly discuss how these limitations might have affected your results. Additionally, suggest areas for future research that could build upon your work, addressing any unanswered questions or unexplored aspects. This demonstrates a thoughtful approach to your research.

End with a Strong Conclusion Statement. Conclude your research paper with a strong and memorable statement that reinforces the key message you want readers to take away. This could be a call to action, a proposal for further investigation, or a reflection on the broader significance of your findings. Leave your readers with a lasting impression that emphasizes the importance of your research. Remember that you can buy a research paper anytime if you lack time or get stuck in writer’s block.

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Stylistic Devices to Use in a Conclusion

Discover distinctive stylistic insights that you can apply when writing a conclusion for a research paper:

• Rhetorical Questions. When using rhetorical questions, strategically place them to engage readers' minds. For instance, you might pose a question that prompts reflection on the broader implications of your findings, leaving your audience with something to ponder.
• Powerful Language. Incorporate strong language to convey a sense of conviction and importance. Choose words that resonate with the overall tone of your research and amplify the significance of your conclusions. This adds weight to your key messages.
• Repetitions. Repetitions can be employed to reinforce essential ideas. Reiterate key phrases or concepts in a way that emphasizes their importance without sounding redundant. This technique serves to drive home your main points.
• Anecdotes. Integrating anecdotes into your conclusion can provide a human touch. Share a brief and relevant story that connects with your research, making the information more relatable and memorable for your audience.
• Vivid Imagery. Lastly, use vivid imagery to paint a picture in the minds of your readers. Appeal to their senses by describing scenarios or outcomes related to your research. This creates a more immersive and lasting impression.

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How to Make a Conclusion Logically Appealing

Knowing how to write a conclusion for a research paper that is logically appealing is important for leaving a lasting impression on your readers. Here are some tips to achieve this:

Logical Sequencing

• Present your conclusion in a structured manner, following the natural flow of your paper. Readers should effortlessly follow your thought process, making your conclusion more accessible and persuasive.

Reinforce Main Arguments

• Emphasize the core arguments and findings from your research. By reinforcing key points, you solidify your stance and provide a logical culmination to your paper.

Address Counterarguments

• Acknowledge and address potential counterarguments or limitations in your research. Demonstrate intellectual honesty and strengthen your conclusion by preemptively addressing potential doubts.

Connect with Introduction

• Revisit themes or concepts introduced in your introduction to create a cohesive narrative, allowing readers to trace the logical progression of your research from start to finish.

Propose Actionable Insights

• Suggest practical applications or recommendations based on your findings. This will add a forward-looking dimension, making your conclusion more relevant and compelling.

Highlight Significance

• Clearly articulate the broader implications of your research to convey the importance of your work and its potential impact on the field, making your conclusion logically compelling.

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Avoid These Things When Writing a Research Paper Conclusion

As you write your conclusion of research paper, there’s a list of things professional writers don’t recommend doing. Consider these issues carefully:

• Repetition of Exact Phrases
• Repetitively using the same phrases or sentences from the main body. Repetition can make your conclusion seem redundant and less engaging.
• Overly Lengthy Summaries
• Providing excessively detailed summaries of each section of your paper. Readers may lose interest if the conclusion becomes too long and detailed.
• Unclear Connection to the Introduction
• Failing to connect the conclusion back to the introduction. A lack of continuity may make the paper feel disjointed.
• Adding New Arguments or Ideas
• Introducing new arguments or ideas that were not addressed in the body. This can confuse the reader and disrupt the coherence of your paper.
• Overuse of Complex Jargon
• Using excessively complex or technical language without clarification. Clear communication is essential in the conclusion, ensuring broad understanding.
• Apologizing or Undermining Confidence
• Apologizing for limitations or expressing doubt about your work. Maintain a confident tone; if limitations exist, present them objectively without undermining your research.
• Sweeping Generalizations
• Making overly broad or unsupported generalizations. Such statements can weaken the credibility of your conclusion.
• Neglecting the Significance
• Failing to emphasize the broader significance of your research. Readers need to understand why your findings matter in a larger context.
• Abrupt Endings
• Concluding abruptly without a strong closing statement. A powerful ending leaves a lasting impression; avoid a sudden or weak conclusion.

Research Paper Conclusion Example

That covers the essential aspects of summarizing a research paper. The only remaining step is to review the conclusion examples for research paper provided by our team.

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Final Thoughts

In conclusion, the knowledge of how to write the conclusion of a research paper is pivotal for presenting your findings and leaving a lasting impression on your readers. By summarizing the key points, reiterating the significance of your research, and offering avenues for future exploration, you can create a conclusion that not only reinforces the value of your study but also encourages further academic discourse. Remember to balance brevity and completeness, ensuring your conclusion is concise yet comprehensive. Emphasizing the practical implications of your research and connecting it to the broader academic landscape will help solidify the impact of your work. Pay someone to write a research paper if you are having a hard time finishing your coursework on time.

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How To Write A Conclusion For A Research Paper?

What should the conclusion of a research paper contain, how to start a conclusion paragraph for a research paper.

Daniel Parker

is a seasoned educational writer focusing on scholarship guidance, research papers, and various forms of academic essays including reflective and narrative essays. His expertise also extends to detailed case studies. A scholar with a background in English Literature and Education, Daniel’s work on EssayPro blog aims to support students in achieving academic excellence and securing scholarships. His hobbies include reading classic literature and participating in academic forums.

is an expert in nursing and healthcare, with a strong background in history, law, and literature. Holding advanced degrees in nursing and public health, his analytical approach and comprehensive knowledge help students navigate complex topics. On EssayPro blog, Adam provides insightful articles on everything from historical analysis to the intricacies of healthcare policies. In his downtime, he enjoys historical documentaries and volunteering at local clinics.

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How to Write a Research Paper Conclusion Section

What is a conclusion in a research paper?

The conclusion in a research paper is the final paragraph or two in a research paper. In scientific papers, the conclusion usually follows the Discussion section , summarizing the importance of the findings and reminding the reader why the work presented in the paper is relevant.

However, it can be a bit confusing to distinguish the conclusion section/paragraph from a summary or a repetition of your findings, your own opinion, or the statement of the implications of your work. In fact, the conclusion should contain a bit of all of these other parts but go beyond it—but not too far beyond! 

The structure and content of the conclusion section can also vary depending on whether you are writing a research manuscript or an essay. This article will explain how to write a good conclusion section, what exactly it should (and should not) contain, how it should be structured, and what you should avoid when writing it.  

Table of Contents:

What does a good conclusion section do, what to include in a research paper conclusion.

• Conclusion in an Essay
• Research Paper Conclusion 
• Conclusion Paragraph Outline and Example
• What Not to Do When Writing a Conclusion

The conclusion of a research paper has several key objectives. It should:

• Restate your research problem addressed in the introduction section
• Summarize your main arguments, important findings, and broader implications
• Synthesize key takeaways from your study

The specific content in the conclusion depends on whether your paper presents the results of original scientific research or constructs an argument through engagement with previously published sources.

You presented your general field of study to the reader in the introduction section, by moving from general information (the background of your work, often combined with a literature review ) to the rationale of your study and then to the specific problem or topic you addressed, formulated in the form of the statement of the problem in research or the thesis statement in an essay.

In the conclusion section, in contrast, your task is to move from your specific findings or arguments back to a more general depiction of how your research contributes to the readers’ understanding of a certain concept or helps solve a practical problem, or fills an important gap in the literature. The content of your conclusion section depends on the type of research you are doing and what type of paper you are writing. But whatever the outcome of your work is, the conclusion is where you briefly summarize it and place it within a larger context. It could be called the “take-home message” of the entire paper.

What to summarize in the conclusion

Your conclusion section needs to contain a very brief summary of your work , a very brief summary of the main findings of your work, and a mention of anything else that seems relevant when you now look at your work from a bigger perspective, even if it was not initially listed as one of your main research questions. This could be a limitation, for example, a problem with the design of your experiment that either needs to be considered when drawing any conclusions or that led you to ask a different question and therefore draw different conclusions at the end of your study (compared to when you started out).

Once you have reminded the reader of what you did and what you found, you need to go beyond that and also provide either your own opinion on why your work is relevant (and for whom, and how) or theoretical or practical implications of the study , or make a specific call for action if there is one to be made.   

How to Write an Essay Conclusion

Academic essays follow quite different structures than their counterparts in STEM and the natural sciences. Humanities papers often have conclusion sections that are much longer and contain more detail than scientific papers. There are three main types of academic essay conclusions.

Summarizing conclusion

The most typical conclusion at the end of an analytical/explanatory/argumentative essay is a summarizing conclusion . This is, as the name suggests, a clear summary of the main points of your topic and thesis. Since you might have gone through a number of different arguments or subtopics in the main part of your essay, you need to remind the reader again what those were, how they fit into each other, and how they helped you develop or corroborate your hypothesis.

For an essay that analyzes how recruiters can hire the best candidates in the shortest time or on “how starving yourself will increase your lifespan, according to science”, a summary of all the points you discussed might be all you need. Note that you should not exactly repeat what you said earlier, but rather highlight the essential details and present those to your reader in a different way. 

Externalizing conclusion

If you think that just reminding the reader of your main points is not enough, you can opt for an externalizing conclusion instead, that presents new points that were not presented in the paper so far. These new points can be additional facts and information or they can be ideas that are relevant to the topic and have not been mentioned before.

Such a conclusion can stimulate your readers to think about your topic or the implications of your analysis in a whole new way. For example, at the end of a historical analysis of a specific event or development, you could direct your reader’s attention to some current events that were not the topic of your essay but that provide a different context for your findings.

Editorial conclusion

In an editorial conclusion , another common type of conclusion that you will find at the end of papers and essays, you do not add new information but instead present your own experiences or opinions on the topic to round everything up. What makes this type of conclusion interesting is that you can choose to agree or disagree with the information you presented in your paper so far. For example, if you have collected and analyzed information on how a specific diet helps people lose weight, you can nevertheless have your doubts on the sustainability of that diet or its practicability in real life—if such arguments were not included in your original thesis and have therefore not been covered in the main part of your paper, the conclusion section is the place where you can get your opinion across.    

How to Conclude an Empirical Research Paper

An empirical research paper is usually more concise and succinct than an essay, because, if it is written well, it focuses on one specific question, describes the method that was used to answer that one question, describes and explains the results, and guides the reader in a logical way from the introduction to the discussion without going on tangents or digging into not absolutely relevant topics.

Summarize the findings

In a scientific paper, you should include a summary of the findings. Don’t go into great detail here (you will have presented your in-depth  results  and  discussion  already), but do clearly express the answers to the  research questions  you investigated.

Describe your main findings, even if they weren’t necessarily the ones anticipated, and explain the conclusion they led you to. Explain these findings in as few words as possible.

Instead of beginning with “ In conclusion, in this study, we investigated the effect of stress on the brain using fMRI …”, you should try to find a way to incorporate the repetition of the essential (and only the essential) details into the summary of the key points. “ The findings of this fMRI study on the effect of stress on the brain suggest that …” or “ While it has been known for a long time that stress has an effect on the brain, the findings of this fMRI study show that, surprisingly… ” would be better ways to start a conclusion. 

You should also not bring up new ideas or present new facts in the conclusion of a research paper, but stick to the background information you have presented earlier, to the findings you have already discussed, and the limitations and implications you have already described. The one thing you can add here is a practical recommendation that you haven’t clearly stated before—but even that one needs to follow logically from everything you have already discussed in the discussion section.

Discuss the implications

After summing up your key arguments or findings, conclude the paper by stating the broader implications of the research , whether in methods , approach, or findings. Express practical or theoretical takeaways from your paper. This often looks like a “call to action” or a final “sales pitch” that puts an exclamation point on your paper.

If your research topic is more theoretical in nature, your closing statement should express the significance of your argument—for example, in proposing a new understanding of a topic or laying the groundwork for future research.

Future research example

Future research into education standards should focus on establishing a more detailed picture of how novel pedagogical approaches impact young people’s ability to absorb new and difficult concepts. Moreover, observational studies are needed to gain more insight into how specific teaching models affect the retention of relationships and facts—for instance, how inquiry-based learning and its emphasis on lateral thinking can be used as a jumping-off point for more holistic classroom approaches.

Research Conclusion Example and Outline

Let’s revisit the study on the effect of stress on the brain we mentioned before and see what the common structure for a conclusion paragraph looks like, in three steps. Following these simple steps will make it easy for you to wrap everything up in one short paragraph that contains all the essential information: 

One: Short summary of what you did, but integrated into the summary of your findings:

While it has been known for a long time that stress has an effect on the brain, the findings of this fMRI study in 25 university students going through mid-term exams show that, surprisingly, one’s attitude to the experienced stress significantly modulates the brain’s response to it. 

Note that you don’t need to repeat any methodological or technical details here—the reader has been presented with all of these before, they have read your results section and the discussion of your results, and even (hopefully!) a discussion of the limitations and strengths of your paper. The only thing you need to remind them of here is the essential outcome of your work. 

Two: Add implications, and don’t forget to specify who this might be relevant for: 

Students could be considered a specific subsample of the general population, but earlier research shows that the effect that exam stress has on their physical and mental health is comparable to the effects of other types of stress on individuals of other ages and occupations. Further research into practical ways of modulating not only one’s mental stress response but potentially also one’s brain activity (e.g., via neurofeedback training) are warranted.

This is a “research implication”, and it is nicely combined with a mention of a potential limitation of the study (the student sample) that turns out not to be a limitation after all (because earlier research suggests we can generalize to other populations). If there already is a lot of research on neurofeedback for stress control, by the way, then this should have been discussed in your discussion section earlier and you wouldn’t say such studies are “warranted” here but rather specify how your findings could inspire specific future experiments or how they should be implemented in existing applications. 

Three: The most important thing is that your conclusion paragraph accurately reflects the content of your paper. Compare it to your research paper title , your research paper abstract , and to your journal submission cover letter , in case you already have one—if these do not all tell the same story, then you need to go back to your paper, start again from the introduction section, and find out where you lost the logical thread. As always, consistency is key.    

Problems to Avoid When Writing a Conclusion 

• Do not suddenly introduce new information that has never been mentioned before (unless you are writing an essay and opting for an externalizing conclusion, see above). The conclusion section is not where you want to surprise your readers, but the take-home message of what you have already presented.
• Do not simply copy your abstract, the conclusion section of your abstract, or the first sentence of your introduction, and put it at the end of the discussion section. Even if these parts of your paper cover the same points, they should not be identical.
• Do not start the conclusion with “In conclusion”. If it has its own section heading, that is redundant, and if it is the last paragraph of the discussion section, it is inelegant and also not really necessary. The reader expects you to wrap your work up in the last paragraph, so you don’t have to announce that. Just look at the above example to see how to start a conclusion in a natural way.
• Do not forget what your research objectives were and how you initially formulated the statement of the problem in your introduction section. If your story/approach/conclusions changed because of methodological issues or information you were not aware of when you started, then make sure you go back to the beginning and adapt your entire story (not just the ending). 

Consider Receiving Academic Editing Services

When you have arrived at the conclusion of your paper, you might want to head over to Wordvice AI’s AI Writing Assistant to receive a free grammar check for any academic content. 

After drafting, you can also receive English editing and proofreading services , including paper editing services for your journal manuscript. If you need advice on how to write the other parts of your research paper , or on how to make a research paper outline if you are struggling with putting everything you did together, then head over to the Wordvice academic resources pages , where we have a lot more articles and videos for you.

In a short paper—even a research paper—you don’t need to provide an exhaustive summary as part of your conclusion. But you do need to make some kind of transition between your final body paragraph and your concluding paragraph. This may come in the form of a few sentences of summary. Or it may come in the form of a sentence that brings your readers back to your thesis or main idea and reminds your readers where you began and how far you have traveled.

So, for example, in a paper about the relationship between ADHD and rejection sensitivity, Vanessa Roser begins by introducing readers to the fact that researchers have studied the relationship between the two conditions and then provides her explanation of that relationship. Here’s her thesis: “While socialization may indeed be an important factor in RS, I argue that individuals with ADHD may also possess a neurological predisposition to RS that is exacerbated by the differing executive and emotional regulation characteristic of ADHD.”

In her final paragraph, Roser reminds us of where she started by echoing her thesis: “This literature demonstrates that, as with many other conditions, ADHD and RS share a delicately intertwined pattern of neurological similarities that is rooted in the innate biology of an individual’s mind, a connection that cannot be explained in full by the behavioral mediation hypothesis.”  

Highlight the “so what”  

At the beginning of your paper, you explain to your readers what’s at stake—why they should care about the argument you’re making. In your conclusion, you can bring readers back to those stakes by reminding them why your argument is important in the first place. You can also draft a few sentences that put those stakes into a new or broader context.

In the conclusion to her paper about ADHD and RS, Roser echoes the stakes she established in her introduction—that research into connections between ADHD and RS has led to contradictory results, raising questions about the “behavioral mediation hypothesis.”

She writes, “as with many other conditions, ADHD and RS share a delicately intertwined pattern of neurological similarities that is rooted in the innate biology of an individual’s mind, a connection that cannot be explained in full by the behavioral mediation hypothesis.”  

Leave your readers with the “now what”  

After the “what” and the “so what,” you should leave your reader with some final thoughts. If you have written a strong introduction, your readers will know why you have been arguing what you have been arguing—and why they should care. And if you’ve made a good case for your thesis, then your readers should be in a position to see things in a new way, understand new questions, or be ready for something that they weren’t ready for before they read your paper.

In her conclusion, Roser offers two “now what” statements. First, she explains that it is important to recognize that the flawed behavioral mediation hypothesis “seems to place a degree of fault on the individual. It implies that individuals with ADHD must have elicited such frequent or intense rejection by virtue of their inadequate social skills, erasing the possibility that they may simply possess a natural sensitivity to emotion.” She then highlights the broader implications for treatment of people with ADHD, noting that recognizing the actual connection between rejection sensitivity and ADHD “has profound implications for understanding how individuals with ADHD might best be treated in educational settings, by counselors, family, peers, or even society as a whole.”

To find your own “now what” for your essay’s conclusion, try asking yourself these questions:

• What can my readers now understand, see in a new light, or grapple with that they would not have understood in the same way before reading my paper? Are we a step closer to understanding a larger phenomenon or to understanding why what was at stake is so important?  
• What questions can I now raise that would not have made sense at the beginning of my paper? Questions for further research? Other ways that this topic could be approached?  
• Are there other applications for my research? Could my questions be asked about different data in a different context? Could I use my methods to answer a different question?  
• What action should be taken in light of this argument? What action do I predict will be taken or could lead to a solution?  
• What larger context might my argument be a part of?  

What to avoid in your conclusion  

• a complete restatement of all that you have said in your paper.  
• a substantial counterargument that you do not have space to refute; you should introduce counterarguments before your conclusion.  
• an apology for what you have not said. If you need to explain the scope of your paper, you should do this sooner—but don’t apologize for what you have not discussed in your paper.  
• fake transitions like “in conclusion” that are followed by sentences that aren’t actually conclusions. (“In conclusion, I have now demonstrated that my thesis is correct.”)
• picture_as_pdf Conclusions

How to Write a Conclusion for a Research Paper: Examples & Tips

You might be wondering about how to write a conclusion paragraph for a research paper. It may seem like your readers should understand your main arguments by the end, so there is no need for it. However, there are several aspects that prove the importance of a conclusion section in research.

Its first and primary function is, of course, a summary of all the main ideas and evidence in the paper. Sometimes research can be quite lengthy so putting all the thoughts you want to share in one place is very handy. Moreover, the conclusion shows how important your work is and suggests new ways of looking at the problem.

Our guide and research paper conclusion example are here to help you with your assignment!

• ❗ Importance of a Conclusion
• 👣 Writing Steps
• 📑 Conclusion Types & Examples
• ❌ Common Mistakes

🔗 References

❗ importance of a conclusion in a research paper.

A conclusion intends to remind the readers about the main arguments and findings of the whole paper. However, it also highlights the significance of the work. Both these functions help create a long-lasting, memorable impression from your research paper , so always include this part and try to think of the ways to make it even more effective.

Since having a strong concluding paragraph is so crucial for the overall success, you might want to check out a step-by-step guide on writing it. It can assure you don’t miss any vital moments. Moreover, you need to find out what conclusion type would be the best!

👣 How to Write a Conclusion for a Research Paper Step by Step

Below are only a few simple steps that can allow you to write the most persuasive research paper.

📑 Types & Examples of Research Paper Conclusions

You may be assigned to write a persuasive or argumentative paper. Or your professor might ask you to develop an analytical or comparative research paper.

Should you write their conclusions in the same way? The answer is “No”. When you write different types of assignments, you need different conclusions.

Argumentative Research Paper Conclusion

To write an excellent argumentative paper conclusion, you need to highlight the most persuasive and strong arguments you have — no need to add many details. In addition, don’t forget you should include the essential components of the conclusion, such as paraphrasing your thesis statement, which points out your opinion on the chosen topic. If you used a strong thesis statement generator , it won’t be hard to do.

Argumentative Research Paper Conclusion Example

Right now, Earth is facing the issue of the sixth extinction, which causes numerous species to fade every day. There are at least three ideas people might use to prevent their total extinction in the next fifty years. More ways of recycling, new approaches to plastic production, and conservation of species could be life-saving.

Analytical Research Paper Conclusion

First, you should restate your thesis statement and summarize the critical points of your arguments. The main difference between the analytical research paper conclusion and other types is that there should definitely be a highlight of a broader context. It means you can add some meaning to the findings.

Analytical Research Paper Conclusion Example

Elon Musk has made a revolution in the way we pay, drive, and even fly. His ideas come only from the desire to make things easier, but eventually, they change the world. Musk first thought about PayPal when he was a student, and now it’s one of the most popular online payment systems. The same with Tesla cars.

Comparative Research Paper Conclusion

An effective comparative paper conclusion requires some analytical skills. You need to be very careful in looking through facts to clearly formulate your findings. Moreover, the sources need to be trustworthy. And, as usual, you need to add a paraphrased thesis statement and a few words about the importance of your study research.

Comparative Research Paper Conclusion Example

Electric cars are proven to be more efficient and effective than gas cars. Not only do they produce fewer emissions, but the drivers reach their destination point faster. Moreover, gas cars are more expensive to maintain. It all derives from the specifics of the electric cars’ engines, which are much simpler.

❌ Common Mistakes You Should Avoid

Are you ready to pass your writing? Wait! Have you checked it for the most common mistakes? If no, below are several general errors you should avoid.

• The Conclusion – Organizing Academic Research Papers
• Conclusions – UNC Writing Center
• Conclusions // Purdue Writing Lab
• Writing the conclusion – Research & Learning Online
• Writing a Research Paper – The Writing Center – UW–Madison
• How to Structure & Organize Your Paper
• Writing Conclusions: Writing Guides
• Ending the Essay: Conclusions
• Tips for Writing Policy Papers – Stanford Law School
• A Process Approach to Writing Research Papers
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Great article! It helped me to complete my research papers conclusion that was a real nightmare for me! Thank you so much for it!

I was on my way to completing my research paper and going to finish the conclusion by copy-pasting the introduction. Thank God, I wanted to read some articles on conclusion writing. After reading your post on this question, I completed my conclusion following your instructions. Believe my research paper is worth an excellent mark!

In response to a comment from Lynn: Thank you for noting this unfortunate mistake in the text. Obviously, we spend a lot of time compiling, writing, and editing materials, but there’s always room for a simple human error! Thanks again, and have a great day! 🙂

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How to End a College Essay: Strategies and Examples

Writing a college essay takes skill, but making a strong college essay conclusion is often the most important part. A great ending can make a big impact on your readers and bring your main ideas together. This guide will walk you through four strategies that will help you create impactful conclusions that resonate with your audience.

1. Writing a Memorable College Essay Conclusion

The conclusion of your essay is your last chance to strengthen your main points and leave a lasting impression. A well-written ending can make your whole essay better and more memorable.

Successful Essay Ending Examples

Here are some great ways to end an essay:

• Share a thoughtful idea that connects to your main point, giving a sense of closure and understanding.
• Quickly go over your main points, showing them in a new way.
• Discuss why your topic matters beyond just your essay.
• Link back to your introduction, making your writing feel complete.

Example: 

"When I started looking into how music affects the brain, I didn't know I'd find a connection to my grandmother's struggle with Alzheimer's. I learned that songs people know well can often bring back memories for patients, even when they have trouble talking. This discovery changed how I see music's power and gave me a new way to connect with my grandmother. When we hum her favorite songs together, I see hints of recognition in her eyes, reminding me that sometimes, big scientific ideas can have very personal effects."

Common Mistakes in Ending an Essay

Avoid these problems when writing your college essay conclusion:

• Adding new ideas: Your conclusion should bring together existing points, not introduce new information.
• Just repeating your main point: While it's important to remind readers of your main idea, simply saying it again word-for-word doesn't work well.
• Using overused phrases: Don't use expressions like "In conclusion" or "To sum up."
• Stopping too suddenly: Make sure your conclusion gives a feeling of completion and doesn't leave readers hanging.

Aithor's advanced language model can help you write compelling conclusions that avoid these common mistakes and enhance the overall impact of your essay.

2. Thought-Provoking Questions: A Powerful Way to End an Essay

Ending an essay with a question that makes people think can get your readers interested and encourage them to keep thinking about your topic. This approach leaves a strong impression and can make your essay more memorable.

"After looking at how social media changes how we see ourselves, we're left with an important question: Can we find a way to share our lives online while still living them fully offline? Maybe the answer isn't choosing between the online and real worlds, but learning how to connect well in both."

When using this method, make sure your question is:

• Related to your essay's main topic
• Open-ended, encouraging deeper thought
• Not easy to answer with just "yes" or "no"

3. How to End Your College Essay with a Call to Action

A call to action (CTA) in your conclusion can encourage your readers to do something based on the ideas you've talked about. This works well for essays about social issues, environmental problems, or personal growth topics.

"In this essay, we've looked at the problem of plastic in our oceans. Now, it's time to help fix it. Start by replacing one single-use plastic item you use every day with something you can use again. It could be as simple as using a reusable water bottle or bringing your own bags to the store. Tell your friends and family what you're doing. By taking these small steps, we're not just making less waste; we're starting a chain reaction that can lead to cleaner oceans and a healthier planet."

When writing a CTA for your college essay conclusion, make sure it's:

• Clear and easy to write
• Directly related to your essay's main points
• Something your readers can actually do

Aithor can assist you in writing perfect calls to action that connect with your readers and fit well with your essay's content.

4. Personal Anecdotes: An Engaging Essay Ending

Ending an essay with a personal story can help your readers feel connected to you and strengthen your main message. This approach makes your writing more relatable and human.

"Last summer, I helped at a local animal shelter. One day, they brought in an older, scruffy dog named Max. For weeks, people passed him by, always choosing younger, cuter puppies instead. I started spending extra time with Max, and slowly, his playful side came out. When a family finally took him home, the happiness on their faces – and Max's wagging tail – showed me how important it is to give every living thing a chance. This taught me more about patience, unfair judgments, and the power of second chances than any book ever could."

When using a personal story to end your college essay:

• Make sure it relates to your main topic
• Keep it short and powerful
• Use clear language to paint a picture for your readers

Tips on How to End a College Essay

To write a strong conclusion, think about these extra tips on how to end a college essay:

• Wrap up your main points clearly while suggesting how they might apply to other things or future ideas to keep your readers thinking.
• Make sure your conclusion sounds like the rest of your essay for a smooth, polished finish.
• Don't weaken your arguments by sounding unsure in your conclusion.
• Be extra careful with grammar and punctuation in your conclusion, as it's the last thing your readers will remember.
• Write your conclusion to connect with your specific readers, whether they're college admissions staff, teachers, or other students.
• Write a short and powerful conclusion that drives your main points home without repeating too much or using too many words.

Remember, your conclusion is your last chance to make a strong impression. Take your time to write it carefully, making sure it ties together your main points and shows why your essay matters.

For those wondering how to end a reflection paper, Aithor can help you improve your college essay conclusion, making sure it's polished, powerful, and fits your specific needs. This top writing tool can help you refine your essay ending examples and give you guidance on how to end a reflection paper or any other type of school writing.

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Literature Review

12 Best Tools For Perfect Research Summary Writing

Discover the 12 best tools to streamline your research summary writing, ensuring clarity and precision every time.

Aug 29, 2024

Consider you finally find the time to tackle that research paper for your class. You pull up your literature search and see dozens of articles and studies staring back at you. As you scroll through the titles and abstracts, you realize you need to figure out how to summarize the research to get started on your paper. 

Writing a practical research summary can feel daunting, but it doesn’t have to. In this guide, we’ll break down what a research summary is, why it’s essential, and how to write one. This information lets you confidently write your research summary and finish your paper. 

Otio’s AI research and writing partner can help you write efficient research summaries and papers. Our tool can summarize academic articles so you can understand the material and finish your writing.

Table Of Contents

What is a research summary, purpose of a research summary, how do you write a research summary in 10 simple steps, what is a phd research summary, examples of research summary, supercharge your researching ability with otio — try otio for free today.

A research summary is a piece of writing that summarizes your research on a specific topic. Its primary goal is to offer the reader a detailed study overview with critical findings. A research summary generally contains the structure of the article. 

You must know the goal of your analysis before you launch a project. A research overview summarizes the detailed response and highlights particular issues. Writing it may be troublesome. You want to start with a structure in mind to write a good overview. 

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A research summary provides a brief overview of a study to readers. When searching for literature, a reader can quickly grasp the central ideas of a paper by reading its summary. It is also a great way to elaborate on the significance of the findings, reminding the reader of the strengths of your main arguments. 

Having a good summary is almost as important as writing a research paper. The benefit of summarizing is showing the "big picture," which allows the reader to contextualize your words. In addition to the advantages of summarizing for the reader, as a writer, you gain a better sense of where you are going with your writing, which parts need elaboration, and whether you have comprehended the information you have collected. 

1. Read The Entire Research Paper

Before writing a research summary , you must read and understand the entire research paper. This may seem like a time-consuming task, but it is essential to write a good summary. Make sure you know the paper's main points before you begin writing.

2. Take Notes As You Read

As you read, take notes on the main points of the paper. These notes will come in handy when you are writing your summary. Be sure to note any necessary information, such as the main conclusions of the author's writing. This helpful tip will also help you write a practical blog summary in less time.

3. Organize Your Thoughts

Once you have finished reading and taking notes on the paper, it is time to start writing your summary. Before you begin, take a few minutes to organize your thoughts. Write down the main points that you want to include in your summary. Then, arrange these points in a logical order.

4. Write The Summary

Now that you have organized your thoughts, it is time to start writing the summary. Begin by stating the author’s thesis statement or main conclusion. Then, briefly describe each of the main points from the paper. Be sure to write clearly and concisely. When you finish, reread your summary to ensure it accurately reflects the paper's content.

5. Write The Introduction

After you have written the summary, it is time to write the introduction. The introduction should include an overview of the paper and a summary description. It should also state the main idea.

6. Introduce The Report's Purpose

The summary of a research paper should include a brief description of the paper's purpose. It should state the paper's thesis statement and briefly describe each of the main points of the paper.

7. Use Keywords To Introduce The Report

When introducing the summary of a research paper, use keywords familiar to the reader. This will help them understand the summary and why it is essential.

8. State The Author's Conclusions

The summary of a research paper should include a brief statement of the author's conclusions. This will help your teacher understand what the paper is trying to achieve.

9. Keep It Concise

A summary should be concise and to the point. It should not include any new information or arguments. It should be one paragraph long at maximum.

10. Edit And Proofread

After you have written the summary, edit and proofread it to ensure it is accurate and precise. This will help ensure that your summary is effective and free of any grammar or spelling errors.

1. Otio: Your AI Research Assistant  

Knowledge workers, researchers, and students today need help with content overload and are left to deal with it using fragmented, complex, and manual tooling. Too many settle for stitching together complicated bookmarking, read-it-later, and note-taking apps to get through their workflows. Now that anyone can create content with a button, this problem will only worsen. Otio solves this problem by providing researchers with one AI-native workspace. It helps them: 

1. Collect a wide range of data sources, from bookmarks, tweets, and extensive books to YouTube videos. 

2. extract key takeaways with detailed ai-generated notes and source-grounded q&a chat. , 3. create draft outputs using the sources you’ve collected. .

Otio helps you to go from a reading list to the first draft faster. Along with this, Otio also enables you to write research papers/essays faster. Here are our top features that researchers love: AI-generated notes on all bookmarks (Youtube videos, PDFs, articles, etc.), Otio enables you to chat with individual links or entire knowledge bases, just like you chat with ChatGPT, as well as AI-assisted writing. 

Let Otio be your AI research and writing partner — try Otio for free today ! 

2. Hypotenuse AI: The Versatile Summarizer  

Like all the AI text summarizers on this list, Hypotenuse AI can take the input text and generate a short summary. One area where it stands out is its ability to handle various input options: You can simply copy-paste the text, directly upload a PDF, or even drop a YouTube link to create summaries. 

You can summarize nearly 200,000 characters (or 50,000 words) at once. 

Hypotenuse AI summarizes articles, PDFs, paragraphs, documents, and videos. 

With the AI tool, you can create engaging hooks and repurpose content for social media. 

You'll need a paid plan after the 7-day free trial. 

There needs to be a free plan available. 

The AI tool majorly focuses on generating eCommerce and marketing content. 

3. Scalenut: The Beginner-Friendly AI Summarizer  

Scalenut is one of the powerful AI text summarizers for beginners or anyone starting out. While it's not as polished as some other business-focused apps, it's significantly easier to use — and the output is just as good as others. If you want a basic online text summarizer that lets you summarize the notes within 800 characters (not words), Scalenut is your app. 

With Scalenut, you get a dedicated summary generation tool for more granular control. 

The keyword planner available helps build content directly from the short and sweet summaries. 

The AI tool integrates well with a whole suite of SEO tools, making it a more SEO-focused summarizer. 

You only get to generate one summary per day. 

Scalenut's paid plans are expensive compared to other AI tools. 

You must summarize long-form articles or blogs at most the limit of 800 characters. 

4. SciSummary: The Academic AI Summarizer  

SciSummary is an AI summarizer that helps summarize single or multiple research papers. It combines and compares the content summaries from research papers, article links, etc. 

It can save time and effort for scientists, students, and enthusiasts who want to keep up with the latest scientific developments. 

It can provide accurate and digestible summaries powered by advanced AI models that learn from feedback and expert guidance. 

It can help users read between the lines and understand complex scientific texts' main points and implications. 

It may only capture some nuances and details of the original articles or papers, which may be necessary for some purposes or audiences. 

Some types of scientific texts, such as highly technical, specialized, or interdisciplinary, may require more domain knowledge or context. 

Some sources of scientific information, such as websites, videos, or podcasts not in text format, may need help summarizing. 

5. Quillbot: The AI Summarizer for Academic Papers  

QuillBot uses advanced neural network models to summarize research papers accurately and effectively. The tool leverages cutting-edge technology to condense lengthy papers into concise and informative summaries, making it easier for users to navigate vast amounts of literature. 

You can upload the text for summarization directly from a document. 

It's excellent for summarizing essays, papers, and lengthy documents. 

You can summarize long texts up to 1200 words for free. 

The free plan is limited to professionals. 

There could have been some more output types. 

QuillBot's Premium plan only gives you 6000 words for summaries per month. 

6. Scribbr: The Research Paper Assistant  

Scribbr is an AI-driven academic writing assistant with a summarization feature tailored for research papers. The tool assists users in the research paper writing process by summarizing and condensing information from various sources, offering support in structuring and organizing content effectively. 

7. TLDR This: The Online Article Summarizer  

TLDR This uses advanced AI to effectively filter out unimportant arguments from online articles and provide readers only with vital takeaways. Its streamlined interface eliminates ads and distractions while summarizing key points, metadata, images, and other crucial article details. 

TLDR This condenses even very lengthy materials into compact summaries users can quickly consume, making it easier to process a vast range of internet content efficiently. 

Ten free "AI" summaries 

Summarization of long text 

Basic summary extraction 

Premium option cost 

No significant improvement in premium options 

8. AI Summarizer: The Text Document Summarizer  

AI Summarizer harnesses artificial intelligence to summarize research papers and other text documents automatically. The tool streamlines the summarization process, making it efficient and accurate, enabling users to extract essential information from extensive research papers efficiently. 

Easy-to-understand interface 

1500-word limit 

Multiple language support 

Contains advertisements 

Requires security captcha completion 

Struggles with lengthy content summarization 

9. Jasper: The Advanced Summarizer  

Jasper AI is a robust summarizing tool that helps users generate AI-powered paper summaries quickly and effectively. The tool supports the prompt creation of premium-quality summaries, assisting researchers in distilling complex information into concise and informative outputs. 

Jasper offers some advanced features, like generating a text from scratch and even summarizing it. 

It integrates well with third-party apps like Surfer, Grammarly, and its own AI art generator. 

It's versatile and can be used to create summaries of blogs, articles, website copy, emails, and even social media posts. 

There's no free plan available — though you get a 7-day free trial. 

You'll need to have a flexible budget to use Jasper AI. 

The Jasper app has a steep learning curve. 

10. Resoomer: The Summary Extractor  

Resoomer rapidly analyzes textual documents to determine the essential sentences and summarizes these key points using its proprietary semantic analysis algorithm. 

By automatically identifying what information matters most, Resoomer can condense elaborate texts across diverse subjects into brief overviews of their core message. With swift copy-and-paste functionality requiring no signup, this specialized tool simplifies the reading experience by extracting only vital details from complex writings. 

Clear and accurate summaries 

Creative sentence combining 

Variety of modes and options 

Lengthy text summarization without word limit in premium mode 

Confusing interface with irrelevant features 

Long-winded summaries spread across multiple pages 

11. Anyword: The Marketing-Focused Summarizer  

When I saw Anyword's summary, I could easily state that the content was unique and worth sharing, making this AI tool an excellent choice for marketers. Plus, it's very easy to use.  

Once you've copied-pasted the text and chosen a summary type, paragraph, keywords, or TL;DR, it generates a summary in minutes. Approve it; you can share the text directly without worrying about plagiarized content. 

You can test the AI tool with the 7-day free trial. 

The Anyword's text generator and summarizer are perfect for creating long-form pieces like blog posts with snippets. 

You can give detailed prompts to the AI tool to customize the generated text. 

Any word is expensive for a more limited set of features than other AI summarizers. 

It can sometimes be slower to use. 

There is no free Anyword plan available. 

12. Frase: The SEO Summarizer  

Frase is a powerful AI-powered summarizer that focuses on SEO. This means it can generate summaries that attract audiences and rank higher. Its proprietary model stands out, providing more flexibility, competitive pricing, and custom features. 

Frase uses BLUF and Reverse Pyramid techniques to generate summaries, improving ranking chances. 

It's free to use Frase's summary generator. 

Instead of GPT-3.5 or GPT-4, Frase uses its proprietary model. 

There's no way to add links to the blog or article to generate a summary. 

You can input up to 600-700 words for summarization. 

It might not be an ideal article summarizer for those who don't care about SEO. 

A research summary for a PhD is called a research statement . The research statement (or statement of research interests) is included in academic job applications. It summarizes your research accomplishments, current work, and future direction and potential. The statement can discuss specific issues such as funding history and potential requirements for laboratory equipment and space and other resources, possible research and industrial collaborations, and how your research contributes to your field's future research direction. 

The research statement should be technical but intelligible to all department members, including those outside your subdiscipline. So keep the “big picture” in mind. The strongest research statements present a readable, compelling, and realistic research agenda that fits well with the department's needs, facilities, and goals. Research statements can be weakened by: overly ambitious proposals lack of apparent direction lack of big-picture focus, and inadequate attention to the needs and facilities of the department or position. 

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Research Summary Example 1: A Look at the Probability of an Unexpected Volcanic Eruption in Yellowstone 

Introduction  .

If the Yellowstone supervolcano erupted massively , the consequences would be catastrophic for the United States. The importance of analyzing the likelihood of such an eruption cannot be overstated.  

Hypothesis  

An eruption of the Yellowstone supervolcano would be preceded by intense precursory activity manifesting a few weeks up to a few years in advance.  

Results     

Statistical data from multiple volcanic eruptions happening worldwide show activity that preceded these events (in particular, how early each type of activity was detected).   

Discussion and Conclusion  

Given that scientists continuously monitor Yellowstone and that signs of an eruption are normally detected much in advance, at least a few days in advance, the hypothesis is confirmed. This could be applied to creating emergency plans detailing an organized evacuation campaign and other response measures.     

Research Summary Example 2: The Frequency of Extreme Weather Events in the US from 2000-2008 as Compared to the ‘50s

Weather events bring immense material damage and cause human victims.    

Extreme weather events are significantly more frequent nowadays than in the ‘50s.   

Several categories of extreme events occur regularly now and then: droughts and associated fires, massive rainfall/snowfall and associated floods, hurricanes, tornadoes, Arctic cold waves, etc.   

Discussion and Conclusion 

Several extreme events have become significantly more frequent recently, confirming this hypothesis. This increasing frequency correlates reliably with rising CO2 levels in the atmosphere and growing temperatures worldwide. 

In the absence of another recent significant global change that could explain a higher frequency of disasters, and knowing how growing temperature disturbs weather patterns, it is natural to assume that global warming (CO2) causes this increase in frequency. This, in turn, suggests that this increased frequency of disasters is not a short-term phenomenon but is here to stay until we address CO2 levels.  

Researchers, students, and knowledge workers have long struggled with the initial stages of research projects. The early steps of gathering and organizing information , taking notes, and synthesizing the material into a coherent summary are vital for establishing a solid foundation for any research endeavor. 

These steps can be tedious, overwhelming, and time-consuming. Otio streamlines this process so you can go from the reading list to the first draft faster. Along with this, Otio also helps you write research papers/essays faster. Here are our top features that researchers love: 

AI-generated notes on all bookmarks (Youtube videos, PDFs, articles, etc.), Otio enables you to chat with individual links or entire knowledge bases, just like you chat with ChatGPT, as well as AI-assisted writing. 

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How to Write an Essay Outline: Examples, FAQs & Tips

An essay outline is a structured plan that organizes the main points and supporting details of an essay before writing. It guides the flow of ideas and ensures that each section of the essay is logically connected and coherent.

In this article, we'll walk you through the steps to build a strong essay outline. You'll discover how to define your thesis, arrange your main points, and structure your outline for clarity and effectiveness. If you're still having trouble putting your outline together after reading this, EssayService can provide expert help to make sure your essay is well-structured and persuasive!

Basic Elements of an Essay

An essay begins with an introduction, which is followed by one or more body paragraphs that expand on the points introduced. It ends with a conclusion that restates the thesis and summarizes the main ideas from the body paragraphs.

Introduction

The introduction of an essay introduces the topic and engages the reader from the start. It usually starts with a hook—a statement or question that grabs attention. After the hook, some background information is given to provide context for the topic.

The introduction ends with a thesis statement, which clearly presents the main argument or purpose of the essay. This section not only introduces the topic but also outlines what the essay will cover, setting the tone for what follows.

Avoid these pitfalls:

• Don't try to cover too much ground in your introduction.
• Avoid vagueness. Be specific and precise in your language.

Body Paragraphs

The body of the essay is where your main ideas and arguments take shape. Each paragraph should open with a topic sentence that clearly states the main point. This is followed by supporting details like evidence, examples, and analysis that back up the topic sentence.

Smooth transitions between paragraphs are key to maintaining a logical flow throughout the essay. Together, the body paragraphs build and support the thesis by adding depth and detail to your argument.

Remember these tips for effective body paragraphs:

• Begin each paragraph with a clear and concise topic sentence.
• Use specific examples, facts, or quotes to support your point.
• Explain why the evidence is important and how it relates to your argument.

The conclusion of an essay wraps up the argument and reinforces the thesis. It usually starts by restating the thesis and reflecting on the discussion and evidence presented in the body paragraphs. A brief summary of the main points follows, highlighting the key arguments made throughout the essay.

The conclusion should close with a final thought or call to action, leaving the reader with something to think about or a sense of closure. The aim is to make a lasting impression that emphasizes the importance of the essay's conclusions.

Remember these tips:

• Briefly recap the key arguments you've made.
• Leave the reader with a thought-provoking final sentence or a call to action.
• Don't introduce any new ideas or arguments in your conclusion.

How to Write an Essay Outline?

Now, let's dive into the heart of this article and show you how to write an essay outline in just four smart steps:

• Determining your thesis and key arguments
• Organizing points into sections
• Adding supporting details
• Drafting a rough outline

Determine Your Thesis and Key Arguments

Your thesis should present a specific point of view or a central idea that your essay will support or explore. Here's how to identify your thesis:

• Ask a question: What is the main point you want to convey?
• Brainstorm: Jot down ideas related to your topic.
• Refine your ideas: Narrow down your focus and develop a clear argument.

Once you have your thesis, identify the main points that support it. These points should be logical, relevant, and comprehensive.

• Divide your thesis: Break down your thesis into its key components.
• Create a mind map: Visually organize your ideas.
• Ask yourself questions: What are the main reasons for your argument? What evidence supports your claims?

Group Main Ideas into Sections

The best way to organize your main points when writing an essay outline depends on the specific topic and purpose of your essay. Experiment with different arrangements to find the one that works best for you. Here are some strategies for organizing your main points:

Add Details to Each Main Idea

When working on your essay outline, remember to choose supporting details that are relevant, specific, and convincing. The more evidence you can provide, the stronger your arguments will be. Consider these tips for developing supporting details for each one.

• Provide examples: "For example, the Great Depression led to a significant increase in homelessness and poverty."
• Cite expert opinions: "As the renowned historian, Eric Hobsbawm, once said, 'The French Revolution was a watershed moment in European history.'"
• Make comparisons and contrasts: "While both cats and dogs make excellent pets, cats are generally more independent, while dogs are more social."
• Offer definitions: "A democracy is a form of government in which the people have the power to elect their leaders."

Make a Rough Outline

Once you've developed supporting details for each main point, you're ready to create a draft outline. This outline will serve as a roadmap for your essay, guiding you through the writing process.

Here's a basic outline template:

• Background information
• Thesis statement

Body Paragraph 1

• Topic sentence
• Supporting detail 1
• Supporting detail 2
• Supporting detail 3

Body Paragraph 2

Body Paragraph 3

• Restate thesis
• Summarize key points
• Final thought

Remember to:

• Use consistent formatting: Indent supporting details.
• Label sections clearly: Use Roman numerals for main points and letters for supporting details.
• Be flexible: Adjust your outline as needed to accommodate new ideas or changes in your argument.

Essay Outline Examples

Now that you have an understanding of the basic structure of an essay outline let's explore some specific examples tailored to different essay genres. Remember, these are just templates, and you should feel free to adapt each essay outline example to fit your unique needs and writing style.

Argumentative Essay Outline

I. Introduction

• Hook: A captivating opening sentence to grab the reader's attention.
• Background information: Relevant context to the topic.
• Thesis statement: A clear and concise statement of your argument.

II. Body Paragraph 1

• Topic sentence: The main point of this paragraph.
• Supporting evidence: Facts, statistics, examples, or expert opinions to support your argument.
• Explanation: Analysis of the evidence and its relevance to your thesis.

III. Body Paragraph 2

• Topic sentence: The second main point of your argument.
• Supporting evidence: Facts, statistics, examples, or expert opinions.

IV. Body Paragraph 3

• Topic sentence: The third main point of your argument.

V. Counterargument

• Acknowledge opposing viewpoint: Briefly mention a counterargument.
• Refute counterargument: Provide evidence or reasoning to disprove the opposing viewpoint.

VI. Conclusion

• Restate thesis: Reiterate your main argument.
• Summarize key points: Briefly recap the main supporting points.
• Final thought: Leave the reader with a memorable and impactful statement.

Expository Essay Outline

• A. Hook: Start with an engaging statement or fact to grab the reader's attention.
• B. Background Information: Provide context or background information necessary for understanding the topic.
• C. Thesis Statement: Clearly state the main point or purpose of the essay.
• A. Topic Sentence: Introduce the main idea of the paragraph.
• B. Explanation/Detail: Provide a detailed explanation or description of the first point.
• C. Evidence/Example: Include evidence or examples to support the explanation.
• D. Analysis: Explain how the evidence or example supports the topic sentence.
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• Published: 03 September 2024

Self-assembly of sustainable plant protein protofilaments into a hydrogel for ultra-low friction across length scales

• Olivia Pabois 1   na1 ,
• Yihui Dong 2   na1 ,
• Nir Kampf   ORCID: orcid.org/0000-0002-6713-6979 2 ,
• Christian D. Lorenz   ORCID: orcid.org/0000-0003-1028-4804 3 ,
• James Doutch 4 ,
• Alejandro Avila-Sierra 5 ,
• Marco Ramaioli 5 ,
• Mingduo Mu 1 ,
• Yasmin Message 1 ,
• Evangelos Liamas 1 , 6 ,
• Arwen I. I. Tyler   ORCID: orcid.org/0000-0003-2116-1084 1 ,
• Jacob Klein   ORCID: orcid.org/0000-0001-6602-0694 2 &
• Anwesha Sarkar   ORCID: orcid.org/0000-0003-1742-2122 1  

Communications Materials volume  5 , Article number:  158 ( 2024 ) Cite this article

Metrics details

• Nanoscale biophysics
• Self-assembly

Designing plant protein-based aqueous lubricants can be of great potential to achieve sustainability objectives by capitalising on inherent functional groups without using synthetic chemicals; however, such a concept remains in its infancy. Here, we engineer a class of self-assembled sustainable materials by using plant-based protofilaments and their assembly within a biopolymeric hydrogel giving rise to a distinct patchy architecture. By leveraging physical interactions, this material offers superlubricity with friction coefficients of 0.004-to-0.00007 achieved under moderate-to-high (10 2 -to-10 3 kPa) contact pressures. Multiscale experimental measurements combined with molecular dynamics simulations reveal an intriguing synergistic mechanism behind such ultra-low friction - where the uncoated areas of the protofilaments glue to the surface by hydrophobic interactions, whilst the hydrogel offers the hydration lubrication. The current approach establishes a robust platform towards unlocking an untapped potential of using plant protein-based building blocks across diverse applications where achieving superlubricity and environmental sustainability are key performance indicators.

Introduction

Achieving superlubricity or near-zero friction with ultra-low sliding friction coefficients (<0.01) is a revolutionary engineering paradigm for energy saving 1 , 2 and biomedical applications 3 . Developing functional materials by exploiting the untapped potential of hydration lubrication achieving oil-free superlubricity at moderate-to-high contact pressures mimicking those found in biology (such as mucinous self-assemblies in healthy oral epithelial surfaces 4 or synovial fluids in articulating cartilage surfaces in healthy human joints 5 ) seems to be an obvious alternative for achieving a sustainable future. Although literature on hydration lubrication has surfaced in the past decade, engineering of eco-friendly, efficient, functional aqueous lubricants remains far from realisation. Many, if not most, aqueous lubricants showing superlubricity employ unilamellar vesicles 6 , solid lubricants 7 , polyzwitterionic brushes 8 , or amphiphilic surfactants 9 that are nearly exclusively derived from synthetic chemistry. Although the recent use of hydrogels offers a unique route for achieving ultra-low friction whilst promoting industrial sustainability objectives, often these hydrogels are prepared following synthetic routes and using lipids, polyacrylamides, and other zwitterionic synthetic polymers 10 , 11 , 12 , 13 , 14 . Therefore, seeking an environmentally friendly source of advanced functional lubricants showing superlubricity remains a critical bottleneck.

Using plant-derived proteins as alternative building blocks to synthetic aqueous lubricants could be an ideal way to address this sustainability issue as they can be naturally sourced in abundance with lower carbon footprints 15 . Although plant proteins suffer from functionality issues owing to their complex quaternary structure and limited solubility, there has been an increased momentum to convert them into functional materials such as microgels, nanostructured films, and amyloid fibrils (fabricated by us 16 and other groups 17 , 18 ) exploiting hydrophobic and coulombic interactions manipulating the physical ordering of their naturally occurring functional amino acids. Nevertheless, converting these sustainable plant proteins into sustainable, functional aqueous lubricant materials achieving superlubricity remains to be demonstrated.

In light of these considerations, the present study reports the first design of a self-assembly of plant protein-derived protofilaments within a biopolymeric hydrogel network as an advanced functional aqueous lubricant material offering superlubricity across length scales. Particularly, we use potato protein, which is a highly biocompatible, non-allergenic plant protein derived from the starch industry as a by-product 19 , to create such protofilaments using a highly facile physical crosslinking method, and then electrostatically assemble them with highly hydrating biopolymeric hydrogels. Striking results from this study demonstrate that a robust liquid-vanishing friction with friction coefficients of ca. 4 × 10 −3 to 7 × 10 −5 ) can be achieved under moderate-to-high contact pressures of 300 kPa to 3 MPa due to the synergistic action of the protofilaments offering the surface-anchoring properties, and the hydrogel providing the water mesh-induced hydration, thus behaving like a polymer brush, but made using ecofriendly materials. Such outstanding lubrication properties are due to the ‘patchy architecture’ of this highly viscoelastic and extensible self-assembled structure, where the areas of the protofilaments uncoated by the hydrogel are available to glue to the surface.

The molecular structure of the bulk and interfacial tribofilms formed by this unique self-assembly were characterised across different length scales combining a wide array of techniques, including imaging (transmission electron (TEM) and atomic force (AFM) microscopy), and scattering (light and small-angle neutron scattering (SANS)). Molecular dynamics (MD) simulations were performed both in the bulk phase and at the surface to gain further insights into the structural mechanism governing the interaction between both components and with the surface. We also thoroughly assessed the lubricant friction-reducing capability at multiscale, using both mini traction machine (macroscale study) and surface force balance (SFB) (nanoscale study). Complementary experiments aiming to get further insight into the adsorption behaviour and viscoelasticity (upon shear and extensional deformation) of the engineered self-assembled structures were additionally conducted with a quartz-crystal microbalance with dissipation monitoring (QCM-D), as well as with rotational and extensional rheometers, in order to subsequently define the key parameters influencing hydration performance. This biocompatible ecofriendly aqueous lubricant showing superlubricity at multiple length scales is a key milestone towards creating highly sustainable, plant-based aqueous lubricant materials in the energy sector 20 , as well as the next generation of engineered biomedical materials, such as artificial synovial fluid, tear and saliva for lifetime lubrication of natural biological contacts.

Results and discussion

Molecular structure of the self-assembled protofilament-hydrogel.

To comprehensively explore the protofilament-hydrogel assembling mechanism, the molecular architecture of each individual component (i.e., the potato protein protofilament (PoPF) and the hydrogel made using naturally occurring biopolymers (i.e., xanthan gum (XGH) or κ -carrageenan (KCH) hydrogels) and their combination (i.e., 2 XGH/PoPF and 2 KCH/PoPF) was resolved at both the nano- and atomistic scales, by employing a very wide range of structural techniques, including dynamic light scattering (DLS) (Fig.  1a ), transmission electron microscopy (TEM) (Fig.  1b ), atomic force microscopy (AFM) (Fig.  1c, e and Supplementary Fig.  1 ), small-angle neutron scattering (SANS) (Fig.  1d ), and molecular dynamics (MD) simulations (Fig.  2 and Supplementary Figs.  2 – 4 ). To this end, we designed a comprehensive protofilament fabrication process using potato protein and induced their self-assembly within a polysaccharide hydrogel (either XGH or KCH)) (see ‘Experimental’ Section). The characterisation of both the bulk (DLS, SANS, and MD simulations) and interfacial film (TEM, AFM, and MD simulations) structures formed by the protofilament-hydrogel systems ultimately enabled shedding light on the molecular process governing their superlubricity. Whilst we mainly focused on using XGH as the hydrogel component, we also outline the importance of the polymer type by pinpointing the specific differences observed using another polysaccharide hydrogel (KCH) where appropriate (Supplementary Fig.  1 ).

a Particle size distribution of potato protein protofilament (PoPF) obtained from dynamic light scattering (DLS) measurements. PoPF displays a hydrodynamic diameter of ca. d H  = 100 nm and a surface charge of ζ = +30 mV. PoPF nanostructure observed by ( b ) transmission electron microscopy (TEM), following negative staining, and ( c ) atomic force microscopy (AFM), following sample deposition onto a negatively charged, hydrophilic (mica) surface and immersion into citrate buffer (pH 3.0). The TEM scale bar is 50 nm. Patatin (main potato protein unit 21 ) monomers seem to aggregate with each other, ultimately forming a nanofibril-like protofilament structure. d Scattered intensity ( I ) as a function of the scattering vector ( q ) for the potato protein protofilament/xanthan gum hydrogel (2 XGH/PoPF) and each individual component (1.2 wt% XGH, and 0.6 wt% PoPF), at 25 °C, measured by small-angle neutron scattering (SANS). Solid lines correspond to fits to the data obtained using the unified model 29 , 30 . e Nanostructure of the self-assembled protofilament/-hydrogel (2 XGH/PoPF) observed by AFM, following sample deposition onto a negatively charged, hydrophilic (mica) surface and immersion into citrate buffer (pH 3.0). A continuously connected protofilament-containing hydrogel network seems to form. Both XGH and the mica surface being negative charge, no adsorption was expected, therefore preventing any structure from being visible once measuring XGH on its own (Supplementary Fig.  1 ). Each measurement was reproduced at least three times; the average measurement is shown.

a Snapshot of the MD simulation of a single potato protein (patatin)-based protofilament (PoPF) in an aqueous solution (radius of gyration ( R g ) = 46.1 ± 0.1 Å, eccentricity = 0.06 ± 0.01). b Snapshot of the MD simulation of xanthan gum (XG) partially coating PoPF in an aqueous solution ( R g  = 44.8 ± 0.1 Å, eccentricity = 0.15 ± 0.01). The XG molecules are represented by the chains of spheres, which are coloured by their element: cyan (carbon), red (oxygen) and white (hydrogen). PoPF is represented by a cartoon that shows the secondary structure of the potato protein (patatin). The cartoon of each patatin in PoPF is coloured differently. c , d Snapshots from the MD simulation of PoPF interacting with XGH in the presence of a PDMS surface, where two PoPF are connected by XGH, whereas the naked (i.e., uncoated by XGH) part of PoPF interacts with PDMS. The PDMS is in the form of a slab, and its molecules are shown as spheres where cyan (carbon), silicon (yellow), red (oxygen) and white (hydrogen) are used to denote the different atoms in the polymer. Contact maps for ( e ) PoPF and PDMS and ( f ) PoPF and XGH.

DLS measurements reveal that PoPF exhibits a monomodal size distribution (Fig.  1a ). Both TEM (Fig.  1b ) and AFM (Fig.  1c and Supplementary Fig.  1 ) images reveal that the 65 °C heat treatment of the 6 wt% potato protein isolate solution fabricated at pH 3.0 results in the formation of long, curly nanofibrillar structures via the aggregation of sphere-shaped patatin (main potato protein unit 21 ) particles, with diameter and height sizes of ca. 20 nm and 3–5 nm, respectively.

Both images have the same scale length (ca. 500 nm), but the sphere-shaped patatin particles are about 10 times larger in the AFM micrograph compared to TEM. The fibrillar length could not be determined given the high level of entanglement. The topographical image (Fig.  1c ) is consistent with observations made with a range of globular, plant-based proteins that are physically hydrolysed at low pH and high temperature 19 , 22 , 23 , 24 , 25 , 26 , 27 , including potato protein for which similar morphologies and dimensions were obtained 19 . Under these conditions, fibrillisation is well known to occur following a ‘polypeptide model’, whereby proteins first hydrolyse into shorter, lower molecular weight peptide fragments, which subsequently undergo intermolecular interactions due to denaturation-induced unfolding, and oligomerise into protofilaments, ultimately assembling into amyloid fibrils 17 , 19 , 22 , 23 , 24 , 25 , 26 , 27 .

Herein, the fibrillar structure formed by PoPF seems to comprise only one protofilament (i.e., no assembled and twisted morphology), therefore not reaching the amyloid-like fibril stage (hence the naming protofilaments). XGH unlike PoPF shows no prominent topographical features (Supplementary Fig.  1 ). This was expected as XGH is negatively charged (ζ = −40 mV 28 and thereby cannot adhere to the negatively charged mica surface, contrary to the positively charged PoPF (ζ = +30 mV). SANS data analysis using the unified model 29 , 30 (Fig.  1d ) reveals that PoPF exhibits a radius of gyration ( R g ) of 75.4 ± 1.5 Å with a fractal dimension of ca 3.3, thus suggesting the formation of structures with a quite rough surface—in agreement with observations made through microscopy (Fig.  1b, c ), while with its power of 1.1, XGH seems to be composed of rod-like objects with a R g of 156.4 ± 4.1 Å forming a quite branched, mass fractal network. Although PoPF seems to form fibril-like structures, the system could not be fitted to a cylinder-type model very likely because of its too high polydispersity and branching. Surprisingly, the combination of PoPF and XGH leads to the formation of convoluted, continuous interconnected filaments that seem to cover the mica surface (Fig.  1e and Supplementary Fig.  1 ). This suggests that PoPF is most likely coated in a ‘patchy way’ by XGH, and catalyses the surface binding of this self-assembly by virtue of its cationic surface charge, whereas XGH glues one protofilament to another, ultimately evolving into a dense, electrospun fibre-like, highly ordered filamentous network. The analysis of data corresponding to their combination suggests objects with a rough surface ( R g  = 74.2 ± 2.5 Å, and fractal dimension of ca. 2.9), which may self-assemble in the shape of large aggregates (Fig.  1d ). Noteworthy, this long, stranded architecture occurring due to XG rigid rods is a signature of 2 XGH/PoPF system; instead, the other polysaccharide (KC) seems to form fractal aggregates when mixed with PoPF (Supplementary Fig.  1 ).

MD simulations both in the bulk and at the interface

To further support the proposed patchy model of PoPF coated by XGH, MD simulations were carried out both in the bulk phase and at the interface, to gain an atomistic description of the interactions taking place between PoPF and the XGH aqueous medium, as well as with a highly hydrophobic, polydimethylsiloxane (PDMS) surface. To the best of our knowledge, this is the first MD simulation study performed on a self-assembled system made up of protofilaments and hydrogels. Using 8 patatin molecules to model a protofilament (Fig.  2a , see ‘Experimental’ section), the snapshots obtained from the simulations clearly show that the XG molecules coat only parts of the PoPF moieties, with the patatin in the PoPF moiety interacting with the XG molecules via its C-terminal end (Fig.  2b ). Remarkably, PoPF is adsorbed onto the surface of the PDMS substrates via its ‘naked’, uncoated area (Fig.  2 c) and XG molecules are able to form bridges between neighbouring PoPF entities (Fig.  2d ). We then identified any pair of residues (which are defined as a monomer in PDMS, an amino acid in the potato protein, and a saccharide in XG) in the different molecules to be in contact if their centre of mass was less than 1.5 nm away from a neighbouring molecule.

The contact map in Fig.  2e shows that PoPF binds to the PDMS surface specifically through residues 72 and 90, and through residues 180 and 200. Both of these regions of the protein contain high densities of hydrophobic residues which may shield themselves from the aqueous environment by interacting with the polymeric interface. The interaction of PoPF with the PDMS substrate causes the PoPF moieties to deform and become both more spherical (eccentricity of 0.13 ± 0.01 at the PDMS surface vs. 0.15 ± 0.01 in solution) and more compact ( R g of 43.6 ± 0.1 Å at the PDMS surface vs. 44.8 ± 0.1 Å in solution). Also, the interactions between the patatins in PoPF and XGH (Fig.  2f ) change, as residues 72–90 in the patatins, which had been interacting with XG in the aqueous phase (primarily through the positively charged residues ARG 70 and LYS 76), preferentially interact with the PDMS polymers (Fig.  2e ). When PoPF is adsorbed to the PDMS substrate, XG seems to bind primarily to the patatins through interactions with the C-terminal end (residues 327–359) of the potato protein, which has a particularly high density of positively charged residues (LYS 327, LYS 328, LYS 343, ARG 344, LYS 347, ARG 352, LYS 353, LYS 354, ARG 356, and LYS 359). When XG is bound to PoPF before it adsorbs to the polymer interface, we also observe interactions between residues 113–137 (there are three LYS residues and several polar residues within this region) and the XG molecules which are not available as a result of PoPF adsorption to the PDMS interface. The patatins are generally found to interact via the same regions, which have a high density of hydrophobic residues interacting with the PDMS surface, whether they are in an isolated protofilament (Supplementary Fig.  2a ), interacting with xanthan gum (Supplementary Fig.  2b ), or interacting with both XGH and PDMS (Supplementary Fig.  2c ). Additionally, XG molecules were shown to interact in a head-to-tail arrangement that facilitates fibre-like formations, such that the one end of a given XG molecule interacts with the opposite end of another molecule (Supplementary Fig.  3 ). In summary, the MD simulations (Fig.  2 ) provide insight into the molecular mechanisms that drive the patchy architecture of XGH on PoPF, which was also observed in the topographical images. This patchy architecture seems to be primarily driven by significant binding to the domains of the proteins that have a high density of cationic residues, while the binding of PoPF to the PDMS surface is as expected driven by hydrophobic interactions between domains of the protein with high densities of hydrophobic residues. It is now worth asking whether such a unique patchy architecture of the self-assembled structure offers synergistic lubricity benefits; this will be discussed later.

Rheological performance

Macromolecular hydrodynamic effects have been considered as a key contributor to lubrication mechanism in biological contact surfaces 4 , 31 , 32 , 33 . In order to understand the role of viscous lubrication in the overall lubricity performance, the resistance to shearing and stretching of the self-assembled protofilament/hydrogel was measured using rotational (Fig.  3a and Supplementary Fig.  5a ) and extensional (Fig.  3b and Supplementary Fig.  5b ) rheometry, respectively.

Evolution of ( a ) the shear viscosity ( η shear ) as a function of the shear rate, obtained from stress-controlled rotational rheometry measurements, and ( b ) the apparent extensional viscosity ( η extensional ) and Trouton ratio ( T r ) as a function of the extensional rate, obtained from extensional rheometry measurements, performed on the potato protein protofilament/xanthan gum hydrogel (2 XGH/PoPF) and each individual component (1.2 wt% XGH, and 0.6 wt% PoPF), at 37 °C. The self-assembled protofilament/hydrogel exhibits a high-viscosity, shear-thinning behaviour, very similar to that of XGH on its own; in comparison, PoPF displays much lower shear viscosity values. While PoPF was found to break at an extremely short time (ca. t b  = 0.014 s), thereby preventing the assessment of its stretchability, both the self-assembled protofilament/hydrogel (2 XGH/PoPF) and XGH show a rise in both the apparent extensional viscosity and   T r  upon increasing extensional rates, more notable so for the latter; for both, particularly the self-assembled system, elastic forces predominate over viscous ones (as T r  > 3). Each experiment was reproduced at least three times; the average and a representative measurement are shown for shear and extensional rheology, respectively.

The shear viscosity evolution was monitored over a broad range of shear rates (0.01–1000 s −1 ) (Fig.  3a ). Irrespective of the type of polymer (XG or KC) used to prepare the hydrogel (Fig.  3a and Supplementary Fig.  5a ), both the self-assembled system (2 XGH/PoPF or 2 KCH/PoPF) and the individual components (PoPF, XGH, and KCH) display a shear-induced viscosity decrease over the whole range of shear rates studied, thereby exhibiting a shear-thinning behaviour. Nonetheless, compared to PoPF, whose shear viscosity does not exceed η shear  = 1.3 ± 0.1 Pa.s at 0.01 s −1 , and diminishes of only two orders of magnitude upon reaching 1000 s −1 , stabilising at a near-plateau from ca. 10 s −1 , XGH and 2 XGH/PoPF were found to display a strikingly sharper (four orders of magnitude), and similar, shear rate-dependent decrease (from η shear  = 1006 ± 122 Pa.s for XGH, and 757 ± 23 Pa.s for 2 XGH/PoPF, at 0.01 s −1 , to 0.052 ± 0.003 Pa.s for XGH, and 0.050 ± 0.002 Pa.s for 2 XGH/PoPF, at 1000 s −1 ). Compared to 2 XGH/PoPF (Fig.  3a ), 2 KCH/PoPF displays an order of magnitude lower viscosity, particularly at 0.01 s −1 (Supplementary Fig.  5a ); such an observation might be associated with the structural differences of the continuous, compact filaments offering more viscosity in contrast to the fractal aggregates (Supplementary Fig.  1 ). Of more importance, the viscosity of the self-assembled protofilament/hydrogel overlaps with that of the hydrogel alone, independently of the polymer types or shear rates tested (Fig.  3a and Supplementary Fig.  5a ). This result highlights that the lubricity difference (if any) between the individual components and the self-assembled system might be predominantly linked to the surface behaviour rather than the viscous behaviour, the latter, being largely dominated by the hydrogel component.

Changes in capillary thread shape (Supplementary Fig.  6 ) and diameter (Supplementary Fig.  7 ) upon extensional deformation were recorded over time, and the evolution of the apparent extensional viscosity ( η extensional ) and T r , which are characteristics of the lubricant viscoelasticity) (Fig.  3b and Supplementary Fig.  5b ) were plotted against extensional rates.

While the extensional rheology of PoPF could not be assessed due to its too short breaking time (ca. t b  = 0.014 s), XGH and the 2 XGH/PoPF systems were found to form very long-lived and slender filaments (Supplementary Figs.  6 and 7 ). Contrary to rotational rheology measurements, which show similar shear viscosity evolutions upon increasing shear rates for the XGH-based samples, extensional rheology measurements demonstrate better resistance to thinning ( t b  = 0.67 ± 0.37 s for 2 XGH/PoPF vs. t b  = 0.51 ± 0.22 s for XGH), lower extensional viscosity values (ca. η extensional  = 24.0 ± 9.1 Pa.s for 2 XGH/PoPF vs. ca. η extensional  = 44.2 ± 27.3 Pa.s for XGH), and lower Trouton ratio values (ca. T r  = 21.0 ± 2.8 for 2 XGH/PoPF vs. ca. T r  = 30.6 ± 6.8 for XGH) for the self-assembled system (Fig.  3b ). Similar trends, but lower in magnitude, were observed in terms of both shear and extensional rheology when changing the polysaccharide type from XGH to KCH (Supplementary Fig.  5 ).

Superlubricity

Usually, friction force measurements are carried out at only one scale, even though lubricity and the value of friction coefficients are known to be highly scale dependent 34 . In order to paint a full picture on the lubrication property of these new self-assembled protofilament/hydrogel systems, friction forces were measured at the macroscale using a PDMS ball-on-disk tribometer, with a contact pressure of 300 kPa 35 , which is representative of lower bound pressures found in biological conditions (Fig.  4 and Supplementary Fig.  9 ), and surface force balance (SFB) measurements were conducted at the nanoscale using mica surfaces, with much higher contact pressures (ca. 3 MPa 36 ), which are more representative of articular joint conditions (Fig.  5 and Supplementary Figs.  11 and 12 ) (see ‘Experimental’ section).

a Speed-dependent evolution of the friction coefficient, obtained from tribology measurements performed with non-charged, hydrophobic (PDMS) surfaces (at the macroscale), on the self-assembled potato protein protofilament/xanthan gum hydrogel (2 XGH/PoPF) and each individual component (1.2 wt% XGH, and 0.6 wt% PoPF), at 37 °C. The lubrication properties of citrate buffer are also shown for comparison purposes. 2 XGH/PoPF shows an outstanding lubrication performance both in the boundary and hydrodynamic regions, exhibiting ultra-low friction coefficients contrary to both PoPF and XGH on their own. b Influence of the pH on the lubrication performance of the self-assembly system (2 XGH/PoPF) assessed by macroscale tribology. pH was changed from 3.0 to 5.0, upon addition of 1.0 M NaOH, and was increased from pH 3.0 to 7.0, before being decreased back to 3.0 with 1.0 M HCl. The superlubricity of 2 XGH/PoPF was retained at a pH below neutral pH (i.e., below the potato protein isolate isoelectric point (pI of ca. 5)). c Time-dependent evolution of the resonance frequency (Δ f ) measured using QCM-D, upon adsorption of the self-assembled potato protein protofilament/xanthan gum hydrogel (2 XGH/PoPF) and each individual component (1.2 wt% XGH, and 0.6 wt% PoPF), in the presence of a PDMS-coated surface. Each sample was injected into the chamber, which was then rinsed with buffer to assess the sample ability to remain adsorbed to the surface following buffer rinsing. For readability purposes, resonance frequencies are only shown for the 5th overtone. Each sample was diluted 20 times prior to any measurements. Both the self-assembled protofilament/hydrogel system and its individual components readily adsorb onto the PDMS surface, with 2 XGH/PoPF showing a much higher extent of adsorption. Each measurement was reproduced at least three times; the average measurement is shown.

Normal force ( F n ), normalised by the radius of curvature ( R  = ca. 1 cm), plotted against the surface separation distance between curved mica surfaces ( D ), interacting across: a potato protein protofilaments (0.6 wt% PoPF), b xanthan gum hydrogel ((0.15 wt% XGH), and c the self-assembled protofilament/hydrogel (2XGH/PoPF); the yellow-shaded region summarizes the data from a . The insets show the force-distance profiles close to the hard-wall separations, on a magnified scale. Empty and filled symbols correspond to first and subsequent approaches. Typical traces of shear force vs. time for the sliding mica surfaces across: d PoPF, e XGH, and f 2XGH/PoPF. The uppermost trace in each graph shows the back-and-forth lateral motion applied to the upper surface, whereas the other traces show the forces transmitted to the lower surface at different loads ( F n ) and friction forces ( F s ). Each set of traces was recorded during the same approach profile. Shear force ( F s ) as a function of the normal force ( F n ) measured between mica surfaces across: g PoPF, h XGH, and i 2XGH/PoPF. Red lines in the main (lin–lin) figure and (lin–log) insets are constant friction coefficients ( μ  = ∂ F s /∂ F n ). Open and solid symbols represent first and second approaches, respectively. Each measurement was reproduced at least two times, and at least two contact positions were done in each pair of mica sheets; a representative measurement is shown.

Unlike plant protein-based microgels 16 , PoPF displays high friction coefficient values over the whole entrainment speed range, reaching up to 1.18 ± 0.05 at 0.004 m s −1 , similarly to citrate buffer at pH 3.0; instead, XGH seems to induce better lubrication, particularly in the hydrodynamic regime, where friction coefficients as low as 0.009 ± 0.002 are obtained at 0.1 m s −1 (Fig.  4a ). Surprisingly, the self-assembly of the protofilaments with the hydrogel synergistically results in an unusual, nearly speed-independent friction curve, with friction coefficient values as low as 0.004 ± 0.005 in the boundary regime (at 0.004 m s −1 ) (Fig.  4a ). When plotted against minimum hydrodynamic film thickness ( h min ) (Supplementary Fig.  8 ), the friction curves of the constituents overlapped with that of the buffer. On the contrary, the self-assembly (2 XGH/PoPF system) showed ultra-low friction independent of the film thickness, showing effective boundary films capable of maintaining low friction forces at low surface separations. Of more interest, pH does not seem to affect the lubrication properties of this self-assembled system, an increase in friction being observed only at a neutral pH of 7.0, where both PoPF and XGH are negatively charged and thus unable to interact with each other (Fig.  4b ). Such an ultra-low macroscopic lubrication performance is also observed when decreasing the polysaccharide/protein ratio from 2 to 0.5 (Supplementary Fig.  9a ) and changing the polysaccharide type from XGH to KCH (Fig.  S9b ). Based upon the complementary interfacial data obtained via QCM-D measurements with PDMS-coated silicon surfaces, the remarkably better lubrication properties exhibited by the self-assembled protofilament/hydrogel may be explained by its 3 times stronger ability to adsorb onto the surface and to remain attached following rinsing, compared to that of the polysaccharide hydrogel and protein protofilaments on their own (Fig.  4c ). Such a high adsorption capacity is rather specific to the use of XGH rather than KCH (Supplementary Fig.  10 ), thus highlighting the importance of the filamentous structure formed in the self-assembled 2 XGH/PoPF system (Fig.  1 e) and of its patchiness visualised through MD simulations (Fig.  2 ). Such an efficient friction-reducing mechanism can be attributed to the synergy between: PoPF almost behaving like a colloidal glue attaching to the surface, and XGH network sporadically interacting with the protofilaments forming a water-encapsulating macromolecular brush, ultimately providing hydration. To further investigate the hydration lubrication provided by this system, and clarify whether such ultra-low friction values were maintained in a high contact pressure situation, SFB measurements were conducted with the 2 XGH/PoPF system.

The normal ( F n (D) ) and shear ( F s ) force profiles, as well as the absolute surface separation between two mica surfaces ( D ) across three different systems: PoPF, XGH, and their self-assembly (2 XGH/PoPF), were measured with SFB. The normal force ( F n ) vs. surface separation ( D ) profiles between the mica surfaces bearing PoPF, XGH, and the self-assembled 2 XGH/PoPF system, across each dispersion in citrate buffer were recorded by SFB (see ‘Experimental’ section) 37 , 38 , and plotted in Fig.  5 as F n ( D )/R in accordance with the Derjaguin approximation 37 , 38 , to normalise for slightly different radii of curvature ( R ) of the mica sheets.

In the case of PoPF alone on both surfaces (Fig.  5 a), a monotonic long-ranged repulsion commencing at ca. D  = 600 nm is observed and may be attributed to steric interactions due to loose multilayer PoPF adsorbed on the surface, as indicated by the AFM micrographs (Fig.  1c ) and the broad DLS size distribution (Fig.  1a ). A sharper rise in F n starts at D  < ca. 300 nm, likely due to the compaction of the initially looser adsorbed PoPF. At the strongest compressions attained in our measurements, the surfaces reach a ‘hard-wall’ separation, D HW  = 300 ± 1  nm for both the first (open symbols) and subsequent (filled symbols) approach. This is equivalent to ca. 150 nm of compacted PoPF on each surface, likely in the form of multiple compacted protofilaments of broad size distribution, as suggested by the broad DLS distribution (Fig.  1a ) and AFM micrographs (Fig.  1c ).

In the case of XGH alone on both surfaces (Fig.  5b ), both the magnitude of the exponentially decaying, long-ranged repulsion, as well as the range of the strong steric repulsion, were much shorter compared to PoPF, with steric forces commencing at separations D  ≤ 50 nm. This suggests a compact and/or very weakly adsorbed layer of XGH on each surface. This is expected as the negatively charged XGH 28 would not adsorb to the negatively charged mica surfaces, but weak adsorption due to short-ranged van der Waals attraction at high buffer salt concentration may be possible. The surface separation ( D HW ) under progressively high compression is then reduced from ca. 25 nm to 0 nm. This indicates that XGH is fully squeezed out from the two mica surfaces under compression, in line with the expected very weak (if any) adsorption between XGH and the similarly (negatively) charged mica surfaces. Such a behaviour resembles the macroscale behaviour observed with high friction coefficient values (Fig.  4a ) supported by the limited adsorption observation with both AFM (Supplementary Fig.  1 ) in the presence of mica surfaces and QCM-D (Fig.  4c ) in the presence of PDMS surfaces.

In the case of the self-assembled 2 XGH/PoPF system (Fig.  5c ), monotonically repulsive interaction commences at ca. 500 nm, similarly to PoPF alone (Fig.  5a , see the shaded region in Fig.  5c ). This likely occurs for similar reasons, i.e., large PoPF adsorbed on the mica surface, though now complexed with XGH. It is of interest that the surface separation due to steric repulsion at the highest applied loads is significantly lower for the 2 XGH/PoPF combination (ca. D HW  = 200 nm) than for PoPF alone (for which ca. D HW  = 300 nm). This indicates that the complexation with XGH may result in lower PoPF adsorption on the negatively charged mica, due to the negative charge on XGH, as well as possibly due to changes in the aggregate structures. Importantly, no squeezing out was seen up to the highest loads applied—which correspond roughly to ca. 30 atm (i.e., 3 MPa) of contact pressure between the mica surfaces, suggesting that XGH complexes strongly with PoPF, leaving nonetheless some non-coated areas on PoPF, which in turn adhere strongly to the mica surfaces, as observed in the MD simulations (Fig.  2c, d ).

Figure  5d–f illustrates typical shear force ( F s ) vs. time ( t ) traces at different loads F n between the mica surfaces across dispersions of PoPF, XGH, and their self-assembly (2 XGH/PoPF) in citrate buffer, in response to the lateral back-and-forth motion applied to the upper surface. We note that typical shear traces across the buffer solution alone show very low frictional dissipation (attributed to hydration lubrication) down to mica-mica contact at high loads (Supplementary Fig.  11 ), demonstrating that the buffer carrier does not influence the frictional results across the macromolecular dispersions. The shear traces (Fig.  5d–f ) reveal clearly the following: frictional forces ( F s ) increase strongly already at quite low loads ( F n ) for PoPF (Fig.  5d ) and XGH (Fig.  5e ), but remain consistently low up to high loads for their self-assembly 2 XGH/PoPF (Fig.  5f ), thus showing excellent lubrication. The corresponding variation of F s vs. F n is summarised in Fig.  5g–i .

The friction coefficient ( µ ) values across both (single-component) PoPF (Fig.  5g ) and XGH (Fig.  5i ) dispersions are on the order of 10 −1 , though the origin of the high friction coefficient ( µ) values is likely different in the two cases. In PoPF case, the protein is positively charged, implying strong adsorption onto the mica surface (in the form of aggregates, as earlier discussed and seen in the AFM micrograph (Fig.  1c )); the poor lubrication very likely results from high-energy dissipation as the PoPF layers slide past each other, suggesting poor hydration of the proteins, which is in line with the macroscale behaviour (Fig.  4a ). We believe that it is less likely that bridging of the PoPF aggregates between the mica surfaces occurs, which would also result in high friction, as seen with other bridging macromolecules 39 , 40 . In the case of the negatively charged XGH (Fig.  5h ), molecules may be weakly adsorbed, as noted earlier, to the negatively charged mica surface via Van der Waals interactions effective at the high salt concentration of the buffer carrier, which strongly screens out the electrostatic interactions. In that case the relatively high friction may be attributed to bridging across the inter-surface gap by the long, linear polysaccharide, as observed in earlier studies of adsorbing polymers 39 . At the highest loads, the weakly-adsorbing XGH, also observed in QCM-D studies (Fig.  4b ), is largely if not entirely squeezed out, leaving at most a thin trapped layer bridging the gap, with high frictional dissipation as the surfaces slide past each other; or if the XGH is entirely squeezed out (see inset to Fig.  5b ), the friction may then be high due to mica-mica contact (Supplementary Fig.  11 ). The sliding velocity-independence of the friction across XGH solution (Supplementary Fig.  12 ) also indicates that the high friction observed with XGH alone is likely to be due to a bridging effect rather than a hydrodynamic one, in line with the earlier observed bridging behaviour 39 . The increased friction force with increasing load forces reflects a higher extent of bridging as XGH is squeezed out.

In strong contrast, for the shear across the 2 XGH/PoPF (Fig.  5i ), the friction, after an initial sharp rise at the lowest loads, is seen to be very low, reaching friction coefficient ( µ ) values in the order of 10 −4 to 10 −5 at the highest loads (at which the corresponding mean contact pressures are of ca. 30 atm). We attribute this as follows. Based on the AFM micrographs of the 2 XGH/PoPF system on mica (Fig.  1e ), the complexation between XGH and PoPF leads to densely packed, thread-like aggregates of pearl-like units (whose size appears roughly half that of the pearl-like units of the aggregates of PoPF alone, Fig.  1c ). This suggests the following scenario: the 2 XGH/PoPF system attaches strongly to the mica surface thanks to the naked (uncoated) areas of PoPF (for which ζ-potential of +30 mV) via a counterion-release mechanism. These partially surface-attached PoPF parts, however, expose the XGH component at their outer surface, and when these highly hydrated XGH moieties slide past each other, hydration lubrication reduces the frictional dissipation to the extremely low values observed (ca. µ  = 10 −4 –10 −5 ). Thus, the role of PoPF (via its positive charge) is to anchor the 2 XGH/PoPF aggregates to the negatively charged substrates, while exposing the outer hydrated XGH component allowing significant friction reduction. The initial sharp rise in friction at the lowest loads (Fig.  5i ), noted above and seen in similar systems previously 41 , is due to viscoelastic dissipation, as the loose PoPF are initially sheared, prior to their compression and compaction at higher loads, on approach and sliding of the surfaces.

In summary, the SFB measurements describing above the interactions between mica surfaces across dispersions of PoPF, XGH, and the 2 XGH/PoPF mixture, together with the AFM micrographs of the corresponding surface structures on mica in these dispersions, shed strong light on the nature of the frictional interactions in these three cases. The high friction conditions are then largely due to molecular interactions (e.g. bond breaking/reforming) as the boundary layers slide past each other, while the low friction arises from much-reduced dissipation due to shear of the sub-nanometre hydration layers in the hydration lubrication mechanism, together with passage over energy barriers as described previously 36 (where phonons are generated leading to the weak dissipation observed). In particular, these studies reveal that the very low friction achieved across the 2 XGH/PoPF system arises from the combined roles of the potato protein protofilaments and the highly hydrated polysaccharide hydrogel: the former acts largely to anchor the surface protofilaments to the (negatively-charged) mica substrate, while the latter provides efficient hydration lubrication by being exposed by the surface-attached protofilaments 42 , 43 , 44 . This underpins and illuminates the molecular mechanisms underlying the findings from the macroscopic tribology phenomena, where a similar synergistic behaviour of PoPF and XGH was apparent.

Summarising all these complementary suite of techniques, we demonstrate that an electrostatic self-assembly of PoPF and XGH (Fig.  6 ) provides efficient hydration lubrication fulfilling the high-pressure, low-friction requirements of biological conditions. This unique self-assembly provides robust boundary lubrication via (1) uncovered PoPF anchoring with surfaces effectively; (2) PoPF glueing to the XGH bringing XGH closer to the surface; whilst (3) the exposed, highly hydrated XGH complexed with PoPF providing the hydration lubrication. A key limitation of the study is that conventional, smooth, highly hydrophobic PDMS surfaces were employed in the macrotribology, QCM-D, and molecular dynamics (MD) simulations measurements, whilst negatively charged, hydrophilic (mica) surfaces were used for the atomic force microscopy (AFM) and surface force balance (SFB) experiments. However, it is worth noting that the superlubricity by these surface-attached protofilament-hydrogel self-assembly can be attributed to the molecular interactions between these boundary layers controlling the frictional dissipation that persisted irrespective of the surfaces used. In addition, the diversity of measurements allowed elucidating the molecular mechanism responsible for such outstanding lubrication properties of this potato protein protofilaments/polysaccharide hydrogel—not only at multiple length scales, but also under varying contact pressure conditions. With these range of measurements and surfaces, we are therefore tackling a wide range of biological applications where pressure many vary from few hundreds to thousands of kilopascals such as oral lubrication to those found in articular joints (MPa), showing the high potential of this aqueous lubricant.

The green mesh represents the potato protein-based protofilaments (PoPF) partially coated by orange-coloured filaments connected to each other representing the xanthan based hydrogels (XGH) where the naked part of PoPF (i.e., uncoated by XGH) interacts with the tribo-contact surfaces shown as grey-coloured ball and the rectangular slab. The hydration lubrication mechanism is shown schematically by the transparent water-like spheres attached to the XGH. Zoomed image in the right shows the intact self-assembly outside of the triboshear condition.

Conclusions

In summary, we have shown that potato protein, a by-product from starch industry, can be converted into a high functional aqueous lubricant material offering superlubricity. The synergistic association of potato protein-based protofilaments with polysaccharide hydrogels in a patchy architecture leading to the formation of continuous, convoluted filaments, offer unmatched, ultra-low friction coefficient values (of 10 −2 to 10 −5 ), at moderate-to-extremely high pressures, resembling the remarkable lubrication behaviour of natural biological systems, such as in the oral mucosa, ocular and articular joints 41 , 45 , 46 . The superior sustainability of potato proteins further makes them an ideal candidate for the rational design of a next generation of sustainable, hydrogel-based aqueous lubricants. Future studies are focusing on extending such protofilament-hydrogel self-assembly based aqueous lubrication to other plant protein systems besides potato protein and also investigating the lubrication performance in surfaces with various degrees of hydrophobicity.

Experimental section

Potato protein isolate (91% protein content) was purchased from Sosa Ingredients (Barcelona, Spain), citric acid monohydrate (P > 99.5%) from Alfa Aesar (Thermo Fisher Scientific, Lancashire, UK), Decon 90 from Decon Lab Ltd (Hove, UK), ammonia solution (25 wt%) and toluene from Fisher Scientific (Thermo Fisher Scientific Inc, Loughborough, UK), isopropanol (P99.8%) from MB Fibreglass (Newtownabbey, UK), and xanthan gum (XG), κ -carrageenan (KC), trisodium citrate dihydrate, hydrochloric acid (HCl, 1 M), sodium azide (NaN 3 , P > 99.5%), silicon oil, sulfuric acid (P95.0–98.0%), and hydrogen peroxide solution (30 wt%) from Sigma-Aldrich (Gillingham, UK). The SYLGARD TM 184 silicone elastomer kit employed to coat the silicon sensors with polydimethylsiloxane (PDMS) for the quartz-crystal microbalance with dissipation monitoring (QCM-D) experiments was obtained from Dow Chemical Company Ltd (Cheadle, UK), and the silicon monomer and cross-linking agent were mixed at a 10:1 w/w ratio. Both ultrapure water, or Milli-Q grade water (18.2 MΩ cm, Merck Millipore, Bedford, MA, USA), and deuterium oxide (D 2 O, P99.9%), provided by Sigma-Aldrich (Gillingham, UK), were used in the experiments. Citrate buffer (pH 3.0) was prepared by mixing 10 mM citric acid monohydrate and 10 mM trisodium citrate dihydrate in adequate proportions so as to reach the appropriate acidic pH. NaN 3 (0.02 wt%) was added to all solutions as a preservative. All reagents were used as supplied without any further purification.

Synthesis of the self-assembled protofilament/hydrogel

Unlike protein-based microgels 16 or microgel-reinforced hydrogels 47 , 48 , protofilaments were first created by acidic hydrolysis of the plant protein, and then assembled with a polysaccharide hydrogel network. The plant protein solution (6.0 wt%) was prepared by adding powdered potato protein isolate in 10 mM citrate buffer at pH 3.0 and stirring for ca. 1.5 h to ensure complete solubilisation. Then, the pH of the solution was adjusted to 3.0 by adding 1 M HCl, the solution was centrifuged at 25,000 ×  g for 30 min, and finally the supernatant was heated at 65 °C for 30 min to form potato protein protofilaments (PoPF). Xanthan gum (XG)-based hydrogel (XGH, 1.5 wt%) was prepared by dissolving powdered XG in 10 mM citrate buffer at pH 3.0 at 21 ± 2 °C and shearing the solution for 24 h under constant stirring for complete hydration. On the other hand, κ -carrageenan (KC)-based hydrogel (KCH, 1.5 wt%) was prepared via the dissolution of powdered KC in 10 mM citrate buffer at pH 3.0 by heating at 95 °C while being sheared for 30 min to ensure complete solubilisation. PoPF was added to XGH or KCH dropwise at 21 ± 2 °C, under gentle stirring, to form the self-assembled protofilament/hydrogel at a 2:1 w/w XGH/PoPF or KCH/PoPF ratio, corresponding to a mixture of 1.2 wt% XGH or KCH and 0.6 wt% PoPF.

Particle size and ζ -potential measurements

Hydrodynamic diameter and surface charge ( ζ -potential) measurements were conducted by dynamic light scattering (DLS) on a Zetasizer Ultra instrument (Nano ZS series, Malvern Instruments Ltd, Malvern, UK), at 25 °C, using folded electrophoretic cells (DTS1070, Malvern Instruments Ltd, Malvern, UK) and 100-fold diluted samples.

Transmission electron microscopy (TEM)

The structure of the self-assembled 2XGH/PoPF protofilament/hydrogel was characterised using TEM, with a FEI Tecnai G2 Spirit-T12 microscope (Thermo Fisher Scientific, Waltham, MA, USA), whose electron gun voltage was fixed at 120 kV. Prior to visualisation, the electron contrast was increased by sample negative staining, using the following protocol: (1) electrostatic cleaning of the homemade, 300 mesh, carbon-coated copper grid with a PELCO easiGlow TM glow discharge cleaning system (Ted Pella Inc, Redding, CA, USA); (2) sample deposition onto the grid, followed by excess liquid blotting and ultrapure water washing; (3) grid staining upon addition of 2.0 wt% uranyl acetate; and (4) air-drying. Nanostructure images were captured using a Gantan CCD camera.

Small-angle neutron scattering (SANS)

SANS measurements were performed on the SANS2D time-of-flight instrument, at ISIS pulsed neutron source (STFC Rutherford Appleton Laboratory, Didcot, UK) 49 , using 1 mm path-length quartz cells (Hellma Analytics, Müllheim, Germany) thermostated at 25 °C with a circulating water bath. SANS2D data were acquired with a polychromatic incident beam of wavelength ( λ ) ranging between 1.75 and 16.5 Å, and with a fixed instrument setup of L 1 =  L 2 = 4 m (where L 1 is the collimation length and L 2 the sample-to-detector distance); a simultaneous scattering vector ( q )-range of 0.004 to 1 Å −1 was achieved using two 1 m 2 detectors at 2.4 and 4 m from the sample, with a q -resolution varying from ca. 2% at the highest q -values to ca. 19% with decreasing q -values, calculated using the Mildner Carpenter equation 50 . Detector images were radially averaged and corrected from the scattering of the empty cell and D 2 O background. Detector efficiency corrections and data normalisation to an appropriate standard were done using MANTID 51 .

Atomic force microscopy (AFM)

The topographic images of the self-assembled 2 XGH/PoPF and 2 KCH/PoPF protofilament/hydrogels, as well as of the individual components (XGH, KCH, and PoPF), were obtained using an atomic force microscope ((MFP-3D SA, Oxford Instruments Asylum Research, Santa Barbara, CA, USA). A silicon tip on silicon nitride, V-shaped cantilever (length: 115 μm; nominal spring constant: 0.35 N/m) (SNL, Bruker, Camarillo, CA, USA) was used as the probe, in non-contact mode under liquid. Samples were coated onto freshly cleaved mica surfaces by deposition of the dispersion onto the surface and incubation for ca. 30 min, and were then covered with citrate buffer at pH 3.0.

Molecular dynamics (MD) simulations

The structure of the patatin (main potato protein unit 21 ) used in these simulations was found in the protein database (1oxw) , and the CHARMM-GUI website was employed to build a model of the resulting PoPF in the MARTINI 3.0.0 forcefield 52 . Using this coarse-grain model, a simulation box was created containing 8 patatin molecules, 66,344 water beads, 720 Na + , and 896 Cl − ions (which corresponds to 0.15 M of NaCl solution, the quantity of ions required to neutralise the charge of the system). This system was simulated using the protocol prescribed by the CHARMM-GUI website 53 , which consists of a minimisation simulation using a soft potential, followed by one using the standard Lennard-Jones potential, and then an equilibration step using the NPT ensemble where a target temperature of 338 K and a target pressure of 1 bar were used. Finally, a production simulation was performed using the NPT ensemble with a target temperature of 338 K and a target pressure of 1 bar. The equilibration simulation was run for 1 ns, and the production NPT simulation for 1 μs. In both simulations, a 20 fs timestep was used. The velocity rescale thermostat was employed in both simulations, while the Berendsen barostat and the Parrinello-Rahman barostat were used in the equilibration simulation and the production simulation, respectively.

The self-assembled PoPF resulting from the coarse-grain simulation was then converted to an all-atom model described by the AMBER forcefield using the CHARMM-GUI 54 implementation of backward.py 55 . This all-atom representation of the system contained 692,689 atoms. This system was then simulated using the simulation protocol for proteins in solution prescribed by CHARMM-GUI 56 , which includes a steepest descent energy minimisation simulation, an equilibration simulation using the NVT ensemble in which the Nose-Hoover thermostat is used to control the temperature at 338 K, and then a production simulation using the NPT ensemble with the Nose-Hoover thermostat and the Parrinello Rahman barostat to control the temperature at 338 K and the pressure at 1 bar, respectively. The equilibration simulation was run for 125 ps with a 1 fs timestep, and the production simulation for 100 ns with a 2 fs timestep. The final 50 ns step of this production simulation was used to carry out the analysis of the PoPF in an aqueous solution.

The final configuration from the all-atom simulation of the PoPF in solution was then used as a starting configuration to investigate the interactions of XG molecules with the potato protein nanoparticle. A model of a XG molecule with six repeat units was built using doGlycans 57 and the GLYCAM forcefield 58 , which is based on AMBER. Twenty of these model XG molecules were then randomly inserted into the aqueous environment forming XGH around the PoPF, resulting in a system that contains 784,545 atoms. Then the same all-atom simulation protocol was used for this system as was used for the final all-atom simulations used to study the PoPF. However, for this system, the production simulation was run for 200 ns. Again, the final 50 ns step of the production simulation was used to carry out the analysis of the PoPF interacting with the XG molecules in an aqueous solution.

Finally, we used the final configuration from the production simulation of the PoPF interacting with the XGH and placed it such that it was within 1.5 nm of the interface of a slab of polydimethylsiloxane (PDMS). In order to create the slab of PDMS, we first built a single PDMS molecule with 13 monomers using PySoftK 59 , and then employed PACKMOL to generate a simulation box with 435 polymers. Using the PolyParGen webserver 60 , the AMBER forcefield description of the PDMS polymer was generated. Then, a series of simulations was carried out using the same protocol to generate an amorphous bulk of PDMS as had been previously used for generating an amorphous substrate of another polymer 61 . First, an energy minimisation with a steepest descent algorithm was performed to remove any high-energy steric clashes from the initial configuration. Then the temperature was equilibrated to 800 K in the NVT ensemble using the Berendsen thermostat for 100 ps. Subsequently, the pressure of the simulation box was equilibrated for 5 ns using the Berendsen thermostat and the Berendsen barostat (target pressure of 1 bar). The production simulation was then conducted using the Nosé-Hoover thermostat and the Parrinello-Rahman barostat, to sample from the true NPT ensemble 62 , 63 . The pressure was kept constant at 1 bar. The simulation began at a temperature of 800 K for 50 ns. Each PDMS molecule was able to diffuse and change its conformation at the high temperature. Following this, a first cooling stage was performed at a constant rate of 10 K ns −1 to a temperature of 600 K. Following 50 ns of simulation time, the system was cooled at a constant rate of 10 K ns −1 to the final target temperature of 350 K, at which point we observed no structural evolution of the polymer chains. Thus, only a short simulation at the final temperature was required to allow the local conformational changes of the polymer chains to occur. Finally, a slab of PDMS polymers was created by extending the z-dimension in the simulation box and conducting another energy minimisation in order to create two interfaces of the polymer slab.

After inserting PoPF and XGH near the top interface of the PDMS, water molecules and the necessary ions were added to maintain a neutral system and a 150 mM NaCl solution in the simulation box. The simulation box was large enough in the z-dimension such that it would allow the nanoparticle to be more than 3 nm from the other interface of PDMS through the periodic boundary conditions in the z-dimension. This resulted in a system containing a total of 878,345 atoms. We used a similar simulation protocol as was employed for the PoPF and XGH/PoPF simulations. For this simulation, the production simulation was run for 250 ns. Again, the final 50 ns step of the simulation was used for the analysis. In all simulations, the TIP3P water model was employed to describe the water molecules interactions 64 .

Rotational rheometry

The resistance to shearing of the self-assembled 2 XGH/PoPF and 2 KCH/PoPF protofilament/hydrogel, as well as of the individual components (XGH, KCH, PoPF), was assessed with a stress-controlled rheometer (Kinexus ultra + rotational rheometer, Malvern Instruments, Malvern, UK), fitted with a stainless-steel cone/plate geometry (2° angle cone/60 mm diameter (CP2/60) combined with a 65 mm diameter plate (PL65)) and equipped with a temperature-controlled Peltier system (with a ±0.1 °C temperature stability at thermal equilibrium). Apparent shear viscosity ( \({{\eta }}_{{{{\rm{shear}}}}}\) ) was recorded over a shear rate ranging from 0.1 to 1000 s −1 , at biologically relevant temperature of 37 °C. Each test was repeated at least three times on triplicate samples; the average measurement is shown.

Extensional rheometry

Resistance to stretching was measured using a HAAKE capillary breakup extensional rheometer (CaBER) 1 (Thermo Electron, Karlsruhe, Germany). The thinning of the midpoint diameter of the capillary bridge generated by the rapid separation of two circular plates (6 mm diameter (D o )) that axially constrained the sample was recorded using a laser micrometre, with a beam thickness of 1 mm and a resolution of 20 μm 47 . The initial separation ( h o ) between the two circular plates was set at 3 mm, leading to an initial aspect ratio ( h 0 / D 0 ) of 0.5. The final axial displacement ( h f ) was set at 10 mm in 50 ms to allow filament thinning. Each sample (ca. 0.1 mL) was injected between the plates using a 1 mL syringe. The experiment was triggered 60 s after loading the sample, to limit shear and temperature preconditioning effects. At least five repetitions were performed at 37 °C. High-speed videos of the experiments were also taken at 1000 frames/s, using a PhantomV1612 high-speed camera (Vision Research, Wayne, NJ, USA), to record the shape evolution of the capillary thread. Due to the displacement of the midpoint of the filament, the images acquired were processed using the ImageJ software to detect the filament interface, and compared to the data acquired with the laser micrometre. For an upper convected Maxwell model, the elastocapillary force balance predicts an exponential diameter decay in time with a characteristic relaxation time ( λ c ) 65 :

where D min is the instantaneous filament midpoint diameter. Surface tension measurements were performed in triplicates using the Wilhelmy plate method (Kruss ST10, KRÜSS GmbH, Hamburg, Germany) (Supplementary Fig.  13 ), at 37 °C and minimum speed (0.5 mm min −1 ) to limit the influence of the shear generated between the sample and measuring plate; the average measurement is shown.

The cylindrical elements of the self-assembled 2 XGH/PoPF and 2 KCH/PoPF protofilament/hydrogel, as well as of the individual components (XGH, KCH, PoPF), at the axial mid-plane plate were subject to a strain ( ε ) expressed as:

The instantaneous strain rate ( \(\dot{\in }\) ) for a cylindrical element of fluid is given by:

The apparent extensional viscosity of the liquid ( \({{\eta }}_{{{{\rm{extensional}}}}}\) ) is therefore expressed as:

For coherence with a recent study 47 , 48 ,the transient Trouton ratio ( T r ) was computed as the ratio between the apparent extensional and shear viscosity:

where the dependence of shear rate on the strain rate has been considered at the denominator.

Macroscale tribology

The lubrication performance was evaluated by tribology, using a conventional mini-traction machine (MTM2, PCS Instruments, London, UK) in combination with smooth hydrophobic elastomeric surfaces, i.e., a PDMS ball (19 mm diameter) and disc (46 mm diameter) in a sliding/rolling motion, displaying a 50 nm surface roughness and 2.0 MPa Young’s modulus 47 , 66 . A constant normal force of 2.0 N, corresponding to a Hertzian contact pressure of ca. 300 kPa 35 , and a temperature of 37 °C were applied. The relative motion of the rolling and sliding surfaces is represented by the entrainment speed, which is the average of the ball and disc linear speeds at the contact point, the sliding/rolling ratio being fixed at 50% (i.e., the contribution of both rolling and sliding to motion being defined as equal). The evolution of the friction coefficient was recorded over an entrainment speed range of 0.0035–1.0 m s −1 . The thickness ( h min ) of the hydrodynamic fluid-film for the samples was estimated using the following equation 35 , 67 , 68 , 69 :

where U is the dimensionless speed parameter ( \(\frac{u{\eta}_{\infty }}{E'r'}\) ), W is the dimensionless load parameter ( \(\frac{{F}_{N}}{{E}^{{\prime} }{{r}^{{\prime} }}^{2}}\) ), η ∞ is the viscosity ( η ) of the fluid-film at the tribologically relevant high-shear rates ( \(\dot{\gamma }\) ) at 1000 s −1 and u is the entrainment speed. The η ∞ often is taken as the limiting high-shear viscosity of the fluid in the rheological measurements (the second plateau in the η – \(\dot{\gamma }\) graphs) and is a measure of the hydrodynamic forces generated by the fluid-film during tribo-contacts 67 , 68 . Each experiment was repeated at least three times on triplicate samples; the average measurement is shown.

Surface force balance (SFB) measurements

The SFB setup (Supplementary Fig.  14 ) and the measurement procedures have been described previously in detail 37 , 38 . Briefly, the cleaved molecularly smooth mica sheets (each ca. 2.5 μm thick) were back-silvered and then glued on hemicylindrical quartz lenses of radius of 10 mm, which were oppositely mounted in a crossed-cylinder orientation in the SFB apparatus. The closest separation between two mica surfaces ( D ) was measured from the wavelength of fringes of equal chromatic order (FECO) (accuracy ca. 2–3 Å).

The normal forces ( F n ) were determined from the bending (Δ D 0  − Δ D ) of the horizontal spring, as follows:

where Δ D 0 is the applied normal motion, Δ D the change of surface separation, and K n the horizontal (normal force) spring constant.

The shear forces ( F s ) were determined through measuring the bending Δ X of the vertical spring, as follows:

where K s is the vertical (shear force) spring constant.

We estimate an uncertainty of ±10 −5 in the SFB measurements arising from thermal drift and optical fringe errors 41 .

Quartz-crystal microbalance with dissipation monitoring (QCM-D) measurements

The capacity to adsorb onto a hydrophobic surface and to remain attached following rinsing was evaluated by using a QCM-D (Q-Sense E4 system, Biolin Scientific AB, Västra Frölunda, Sweden), equipped with PDMS-coated sensors 4 .

Silica-coated QCM-D sensors (QSX-303, Q-Sense, Biolin Scientific AB, Västra Frölunda, Sweden) were first treated by UV/Ozone for 15 min to generate hydrophilic surfaces, and then immersed into sulfuric acid for 1 h, before being sonicated twice in ultrapure water for 10 min and dried under nitrogen. The substrates were further cleaned by immersing them into an RCA silicon wafer cleaning solution (made up of 5:1:1 ultrapure water/ammonia/30% hydrogen peroxide) at 80 °C, for 15 min, to remove any remaining organic/insoluble impurities, and by subjecting them to three cycles of 10-min sonication in ultrapure water, before drying them again under nitrogen. Cleaned surfaces were spin-coated with PDMS (prepared in toluene at a concentration 0.5 wt%) at 5000 RPM (with a 2500 RPM/s acceleration), for 60 s, and finally placed under vacuum overnight, at 80 °C, to ensure efficient PDMS cross-linking.

Prior to any measurement, PDMS-coated silicon substrates were thoroughly cleaned through sequential immersion in toluene (30 s), isopropanol (30 s), and ultrapure water (5 min), before rinsing them extensively with ultrapure water, and drying them under nitrogen. Once assembled, the QCM-D flow cells were prefilled with citrate buffer until reaching a stable baseline. Each sample was diluted (i.e., 20-fold dilution in citrate buffer) before being injected into the PDMS-coated silica sensor-containing cell. Once frequency and dissipation reached a plateau, characteristic of adsorption saturation, buffer was flushed into the cell, to study the desorption behaviour of the surface-adsorbed lubricant. Solutions were injected at a flow rate of 100 μL/min, and measurements conducted at a temperature of 25 ± 2 °C. Changes in resonance frequency (Δ f ) were recorded simultaneously over time. Each experiment was reproduced at least three times; a representative curve is shown for the 5th overtone.

Data availability

The raw data in support of most of the quantitative figures reported in this work are available from the corresponding author upon reasonable request.

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Acknowledgements

The authors acknowledge the European Research Council (ERC) for the provision of funding under the European Union’s Horizon 2020 research and innovation programme (grant agreements: no. 890644) and UKRI Horizon Europe Guarantee Fund (grant agreement: no. EP/X03514X/1). The authors also thank the UKRI Healthy Ageing Catalyst Award (ES/X006565/1) for supporting this research. O.P. acknowledges: the British Society of Rheology (BSR) for the award of the Undergraduate Summer Research Bursary, and the Royal Society for the award of the International Exchanges Scheme that allowed her to conduct a research visit at Weizmann Institute. O.P. thanks ISIS for the provision of beam time on SANS2D ( https://doi.org/10.5286/ISIS.E.RB2000279 ). This work benefitted from the use of the SasView application, originally developed under NSF award DMR-0520547. SasView contains code developed with funding from the European Union’s Horizon 2020 research and innovation programme under the SINE2020 project, grant agreement No. 654000.

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These authors contributed equally: Olivia Pabois, Yihui Dong.

Authors and Affiliations

School of Food Science and Nutrition, University of Leeds, Leeds, LS2 9JT, UK

Olivia Pabois, Mingduo Mu, Yasmin Message, Evangelos Liamas, Arwen I. I. Tyler & Anwesha Sarkar

Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, 76100, Rehovot, Israel

Yihui Dong, Nir Kampf & Jacob Klein

Department of Engineering, King’s College London, London, WC2R 2LS, UK

Christian D. Lorenz

ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot, OX11 ODE, UK

James Doutch

Université Paris-Saclay, INRAE, AgroParisTech, UMR SayFood, 91120, Palaiseau, France

Alejandro Avila-Sierra & Marco Ramaioli

Unilever Research & Development Port Sunlight, Quarry Road East, Bebington, Merseyside, CH63 3JW, UK

Evangelos Liamas

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Contributions

O.P., J.K., C.L., M.R., and A.S. conceptualised the study and designed the experimental protocol. A.S. supervised the study. O.P. designed the study protocol. O.P., M.M., Y.M., and E.L. performed the rotational rheology, macroscale tribology, and QCM-D experiments. O.P. conducted the TEM and AFM measurements with the guidance of N.K. and J.K. O.P. thanks Dr Nadav Elad for his technical support with the TEM experiments. O.P. performed the SANS measurements with the help of J.D. and A.T. C.L. designed and carried out the MD simulation study. Y.D., N.K., and J.K. designed the SFB experiments and performed the data analyses. A.A.S. and M.R. developed and conducted the extensional rheology experiments. O.P., Y.D., A.A.S., C.L., and A.S. prepared the figures, and wrote the main manuscript text. All authors reviewed the manuscript.

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Pabois, O., Dong, Y., Kampf, N. et al. Self-assembly of sustainable plant protein protofilaments into a hydrogel for ultra-low friction across length scales. Commun Mater 5 , 158 (2024). https://doi.org/10.1038/s43246-024-00590-5

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Unveiling the deterioration formation process of the rammed earth city wall site of the Ancient City of Pingyao, a World Heritage Site: occurrence, characterizations, and historic environmental implications

• Published: 02 September 2024
• Volume 16 , article number  156 , ( 2024 )

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• Xiangling Bai 1 ,
• Bin He 1 , 2 ,
• Diyue Zhang 1 ,
• Yingxin Wang 1 ,
• Xiaohong Bai 1 ,
• Fuli Ma 1 &
• Pengju Han 1  

Large, immovable rammed earth buildings in UNESCO World Cultural Heritage sites are at serious risk of disaster due to environmental changes. In this study, the rammed earth city walls (REWs) located in the Ancient City of Ping Yao, a World Cultural Heritage site, affected by heavy precipitation in early October 2021, were used as the research object. The study aimed to specify the details of deterioration through multiple indicator data collection, semi-quantitatively evaluate the degree of deterioration of REWs, and investigate the causes of typical deterioration in REWs with different spatial distributions under the influence of heavy precipitation. Based on the current research and experimental data, and considering the mode of action and form of deterioration, a classification system for the landslide-like collapses of REWs under the influence of precipitation was constructed. Factors such as the influence of heavy precipitation and the REWs' intrinsic features resulted in significant variations in structural properties and deterioration development of REWs with different spatial distribution characteristics. Finally, based on the research in this paper and the conservation ideology of cultural relics that respects the original and minimizes intervention, we propose protection recommendations for the daily management and conservation of the REWs to provide guidance for future research.

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Acknowledgements

We thank the Culture and Tourism Bureau of Jinzhong City for its assistance in assembling the historical data of the rammed earth walls in this study. We thank the Shanxi Key Laboratory of Civil Engineering Disaster Prevention and Control (202104010910025, Shanxi Key Laboratory Project) and the Geotechnical Engineering Research Centre of the Ancient City of Pingyao (Technology Development Service Project) for the assistance in this study.

The research was supported by the Shanxi Key Laboratory of Civil Engineering Disaster Prevention and Control (202104010910025, Shanxi Key Laboratory Project) and the Geotechnical Engineering Research Centre of the Ancient City of Pingyao (Technology Development Service Project).

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Xiangling Bai, Bin He, Diyue Zhang, Yingxin Wang, Hao Li, Xiaohong Bai, Fuli Ma & Pengju Han

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Xiangling Bai designed the research in close collaboration with Pengju Han and with support from Xiaohong Bai, Bin He and Fuli Ma. Xiangling Bai conducted the analysis and analysed the results in collaboration with Diyue Zhang and Hao Li. Xiangling Bai wrote the manuscript with contributions from Pengju Han, Bin He. and Yingxin Wang. All authors reviewed and edited the manuscript.

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Bai, X., He, B., Zhang, D. et al. Unveiling the deterioration formation process of the rammed earth city wall site of the Ancient City of Pingyao, a World Heritage Site: occurrence, characterizations, and historic environmental implications. Archaeol Anthropol Sci 16 , 156 (2024). https://doi.org/10.1007/s12520-024-02058-6

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Received : 08 January 2024

Accepted : 13 August 2024

Published : 02 September 2024

DOI : https://doi.org/10.1007/s12520-024-02058-6

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