Welcome to this installment of Quandary This! Chemistry in the News. In this article, we look into the stuff that makes things stick—especially in challenging wet environments.

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Demonstration of the spreading of a coacervate dense phase underwater (∼1 nM rhodamine B is encapsulated for visibility). Captured at room temperature.

Please Note: All student prompts outlined in the “Challenge” sections below are also made available for easy distribution via our downloadable Student Worksheet.

Adhesives are essential in countless applications, and one of the most persistent challenges in adhesive science is achieving strong, reliable adhesion in wet environments. Adhesives that work in wet environments may not seem important at first, but they play a big role in everyday life and advanced technology. For example, underwater construction—like fixing bridges and ships—need adhesives that can stick even when everything is soaked. In healthcare, adhesives attach sensors and bandages to sweaty skin and even inside the body, where it’s always moist. Even electronics like fitness trackers rely on adhesives that can hold up in humid condition.

Unfortunately, water makes it hard for glue to stick properly. Water interferes with many bonding mechanisms, weakening the interactions between adhesive and substrate. Most conventional adhesives rely on dry bonding mechanisms, and the bonding forces are significantly weakened in the presence of water. Water can act as a barrier between the surfaces or disrupt interactions, and even secure bonds can be disrupted by capillary movement of water in wet environments.

To help overcome these limitations, scientists have turned to biomimicry—studying the structures and proteins that occur in organisms that naturally adhere to wet surfaces, such as mussels, frogs, and geckos.

Below, answer the questions to learn more about the ways researchers have studied organisms to create new adhesives. There are several types of questions for students at various levels of study.

Jump to Section:
General Questions (appropriate for all students)
Challenge 1: Literature Research
Challenge 2: Essay Investigation
Challenge 3: In-Depth Analysis
Suggested Reading

Download the Worksheet

General Questions

For Teaching Professionals: The following questions are intended to help students understand the ways in which scientific study touches their lives by looking at news coverage of research. Students will find the answers to the questions by reading the news article linked in the prompt.

For Students: Answer the following questions, using the C&EN article “AI-designed superglue retains extreme strength under water” or another source of your choice.

  1. Why did scientists turn to nature to look for better alternatives to current adhesives?
  2. The scientists started with a database of 24,000 adhesive proteins. Where were the proteins originally found?
  3. What was one thing all of the proteins found in nature shared?
  4. How did scientists use machine learning (ML) to find better adhesives?
  5. What are two ways the scientists tested the strength of the new glues in real settings?

Challenge 1: Literature Research

For Teaching Professionals: The following questions are intended to help students learn the critical skill of searching trusted sources of information, such as peer-reviewed literature, to find answers to specific questions. We encourage instructors to assign these questions to students enrolled in any introductory chemistry lab or lecture. By using literature to find the answers, students will learn to search and consume trusted scientific content with the intention of uncovering specific information. The grading is up to you, but we strongly recommend holding students accountable for presenting a clear answer to each question and accurately tying that answer to a properly cited source.

For Students: For each of the following questions, provide an answer and cite the source of your information in ACS style. You can view citation examples and guidance in the ACS Style Quick Guide.

All the questions posed below can be answered in the journals, books, and news published by ACS Publications. While it is not the only reputable source of peer-reviewed information, the Suggested Reading list below may help you answer most, if not all, of these questions. Make sure you are logged in to your institution's library portal if you wish to search for additional sources on the ACS Publications website.

  1. What are two reasons that coacervate has superior wet-adhesive capabilities than fibrin glue?
  2. What are five common interactions at the interface of an adhesive and the substrate?
  3. What is the functional group that makes marine mussels’ bond so strong?
  4. How can a material switch from being adhesive to detaching—what can trigger the switch?
  5. What is a method of determining the chemical structure of hydrogels and other adhesives?

Challenge 2: Essay Investigation

For Teaching Professionals: The following essay question is intended to help students go one step beyond simple question and answer research. This exercise encourages students not only to consider multidisciplinary exploration around a topic but also to develop written communication skills. As with other questions in this series, the grading is up to you, but we encourage you to help students develop a clear and concise style. Where possible, utilize chemical drawing utilities or neat handwritten molecules and mechanisms. The ideal answer should take no more than one sheet of paper. The ACS Guide to Scholarly Communication can be a great reference.

For Students: Hydrogels are a promising material due to their toughness but face challenges when it comes to their adhesive properties. Adhesive hydrogels often are not durable enough for long-term use. Discuss the possible ways to overcome this challenge.

Challenge 3: In-Depth Analysis

For Teaching Professionals: The following question will challenge students to uncover understanding around the business and legal implications of technological advance. This challenge is helpful for anyone who wants to build depth of thinking and understanding around the real-world circumstances involved in the application of technology. This may include business students, journalism students, and students interested in studying business or intellectual property law.

For Students: Finding adhesives that work effectively underwater remains a challenge, but new options are becoming available each year. One example is a patent for an adhesive developed by Northwestern University, which cites an article by Zhang et al. Given that patents are designed to secure ownership of novel discoveries and patent citations typically paint the landscape of “prior art” to demonstrate that their discovery is novel, what claim does the patent make that could be considered an advance upon the discoveries outlined in this article? (Hint: view the citation list to find the articles.)

Suggested Reading

If you encounter content that is not free to read, please ensure you are logged into your institution’s library portal. If you still are unable to access the content you need, please recommend the content to your library or contact them directly to let them know there are articles you’d like to read.

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