Stronger, greener instant adhesives: biodegradable polymers outperform commercially available options

Researchers at Colorado State University and their partners have developed an adhesive polymer that is stronger than anything currently available on the market, yet is biodegradable and reusable. The findings, published in the journal Science, show how the common natural polymer P3HB can be chemically redesigned for use as a strong and sustainable binder.

Adhesives are commonly used in many areas such as automotive, packaging, electronics, solar cells, and architecture. Together they form an approximately $50 billion industry that not only underpins much of our modern life, but also contributes to the growing plastic waste problem. This paper describes the team’s work using experiment, simulation, and process modeling to develop alternative polymers.

The project was led by Distinguished Professor Eugene Chen of the university’s Department of Chemistry. Other partners on the paper include Greg Beckham of the National Renewable Energy Laboratory, Professor Ting Hsu of the University of California, Berkeley, and researchers in their group.

Chen explained that poly(3-hydroxybutyric acid), known as P3HB, is a natural bio-based biodegradable polymer produced by microorganisms under appropriate biological conditions. Polymers made this way are not sticky, but his lab has been able to chemically re-engineer their structure so that they can be used on a variety of substrates and surfaces, such as aluminum, glass, and wood. , now able to exhibit stronger adhesion than common petroleum-based non-biodegradable options. . The adhesive strength of the redesigned P3HB can also be adjusted to meet the needs of different applications.

The discovery is part of a larger goal by Cheng’s group to improve and expand our ability to tackle the global plastic pollution crisis. His team is working on a number of initiatives to develop chemically recyclable, biodegradable, and overall more sustainable alternatives to today’s plastic materials. He said that while many people are inherently aware of the lifecycle issues associated with disposable water bottles, adhesives present a more difficult problem and fewer potential solutions.

“Petroleum-based thermoset adhesives such as Gorilla Glue and JB Weld, like thermoplastic hot melts, bond strongly with other materials, which can make recycling and recovery very difficult or impossible. “There is,” he said. “Instead, our approach provides a biodegradable material that can be used in a variety of industries with tunable strength or even higher strength compared to these options.”

Ethan Quinn holds a Ph.D. CSU student and postdoctoral researcher Zhen Zhang served as co-first author of the paper. Quinn said he and Zhang led the work on creating and testing the materials.

“We developed a sample P3HB stick adhesive and were able to use it in conjunction with a commercially available adhesive gun to test its application in sealing corrugated boxes and other properties on steel sheets. ” Quinn said. “We knew the data supported it being stronger than other options, but it performed far better than typical hot melt options and compared to existing adhesives at 15 lbs. I was surprised that I was able to prove that I could hold up to 20 pounds in place compared to what I could manage.”

Chen said P3HB is biodegradable in a variety of environments, including controlled and uncontrolled environments. This means that it biodegrades naturally in landfills, just as it does in salty seawater and soil. This widens the range of possible options for processing materials at the end of their life cycle. P3HB adhesive can also be recovered, reprocessed, and reused.

The CSU team will now begin investigating ways to commercialize the polymer for widespread use.

“We are working on two different approaches toward mass production, including ways to lower overall cost and environmental impact,” Chen said. “The analysis conducted by the NREL team has identified key areas for improvement, and we will continue to work with the BOTTLE consortium on our expansion efforts.”