The Future of Sustainable Adhesives

Future Sustainable Adhesives Won't Persist in the Environment To protect our planet and our health, tomorrow's plastics must perform the functions of plastic even if they are not made from plastic itself. One of the important functions plastics perform in our daily lives is adhering objects to various surfaces—just as post-it notes, tape and even bandages do. Professor Mark Grinstaff and his research team from Boston University are working to find environmentally friendly alternatives to plastics. After two years of experimental work, Grinstaff's team developed a soluble adhesive derived entirely from natural chemical components. Presenting their adhesive in Nature Communications, the research team noted that the adhesive formula is highly suitable for use in vastly different sectors that rely on adhesive materials, such as medicine and industry. Grinstaff, Professor of Circular Research at BU's Engineering Faculty, chemistry professor at the College of Arts and Sciences, and director of the Grinstaff Group, stated: "We are replacing non-soluble materials with environmentally better alternatives that perform equally. It is possible to achieve both simultaneously; we just need to be smart about it." Anjeza Beharaj, who completed her doctorate in organic chemistry while working in Grinstaff's laboratory on large molecular structures of chemically bonded materials, particularly polymers, explained: "We wanted to mimic the plastic binders found in paints that allow them to adhere to walls." Although polymers and plastics are often thought to mean the same thing, polymers can actually be made from naturally derived materials, and even our DNA is considered a polymer. Working with Beharaj and Grinstaff were William A. Blessing, who recently completed his doctorate in BU's chemistry department, and undergraduate research assistant Ethan McCaslin. Together, they developed an adhesive system made of soluble polymers that could perform adhesion as well and as effectively as plastic-based products on the market. Beharaj explained: "Our key ingredient is carbon dioxide. This soluble adhesive, which has a consistency like honey or molasses, is composed of approximately 20 to 40 percent CO2. We typically think of carbon as a gas that pollutes the atmosphere, which it does in high quantities. But what is exciting for us is this development: This material allows us to use carbon dioxide that would normally be released into the atmosphere for another purpose, and creates an opportunity for oil refineries and factories to convert this gas into suitable environmentally friendly polymers. This is therefore a win-win situation for both the environment and the customer, because since CO2 is an inexpensive raw material, there is potential to reduce product prices," she added. Unlike plastics that continue to pollute soil for hundreds of years, Grinstaff and Beharaj expect their adhesive to fully biodegrade in nature within approximately one year. McCaslin stated: "This development represents important progress toward creating environmentally friendly products, which should be a priority in today's scientific community." He added that he hoped this adhesive would "inspire more researchers to work on creating environmentally friendly products." Grinstaff's team anticipates that their soluble adhesive can be engineered to replace current plastic adhesives. By adjusting the ratio of polymer and CO2 in each adhesive group, researchers were able to make the material's adhesion stronger or weaker, or to make it suitable for specific surface types. Adhesive strength ranges from that of tape to permanent wood adhesive and can be engineered to bond to metal, glass, wood, Teflon and even wet surfaces. Beharaj also confirmed that using naturally derived and soluble materials in the human body is absolutely safe. These adhesives have the potential to replace metals used to hold bones together in surgery, which could make surgical procedures less invasive. They can also be used on skin surfaces to protect cuts, wounds, abrasions and post-operative incisions. The next step will be to optimize and market these adhesives for use in vastly different fields. Grinstaff concluded: "What we need to do now is find the best application method, and for that we will first learn the needs of people in different fields. The idea in the minds of those working in surgery will differ from that of someone in the packaging industry, but we can address both markets." Source: Materials provided by Boston University. Note: Content may be edited for style and length. Journal Reference: Anjeza Beharaj, Ethan Z. McCaslin, William A. Blessing, Mark W. Grinstaff. Sustainable polycarbonate adhesives for dry and aqueous conditions with thermoresponsive properties. Nature Communications, 2019; 10 (1) DOI: 10.1038/s41467-019-13449-y Boston University. "Chemists develop new biodegradable adhesive: Provides environmentally friendly option to traditional plastic adhesives." ScienceDaily. www.sciencedaily.com/releases/2019/12/191218153406.htm (accessed December 13, 2022).