New Recyclable Sustainable Adhesive
Polymers derived from alpha-lipoic acid (αLA), a small molecule that aids in cell metabolism, have the potential to provide versatile and environmentally friendly adhesives, but their instability has long been a barrier to their use in practical settings. Now, engineers at UC Berkeley have discovered a new chemical strategy that overcomes this impediment, opening the door to high-performance, recyclable adhesives for a wide variety of applications.
As published in the journal Science, researchers have created a new family of stabilized αLA polymer adhesives by slightly altering the chemical composition of their monomers, the small molecules that make up polymers. Using this “modular monomer system,” they tailored the properties of the polymers to create adhesives for medical, consumer, and industrial applications, including a surgical superglue that could significantly advance the field of fetal surgery.
“Once we discovered a chemical approach to this stabilization problem, we had a polymer on our hands that had a multitude of potential uses,” said Phillip Messersmith, principal investigator of the study and a professor of bioengineering and of materials science and engineering. “Most commercially available polymer adhesives are tailored for specific, sometimes narrow uses. But these αLA polymers have shown that they translate well across a range of applications and may be the start of a new industry paradigm, one built around multipurpose adhesives.”
According to Subhajit Pal, first author of the study and a postdoctoral researcher in the Department of Bioengineering, this level of versatility is unique for an adhesive. “I don’t know of any other adhesive system or family where you can mix and match a couple of monomers together in different ratios and get this range of adhesion systems,” he said. “In addition, these novel αLA polymer adhesives often matched or surpassed the performance of commercially available products.”
The new αLA polymers also provide an environmentally friendly adhesive option, in contrast to most consumer and industrial adhesives on the market, which tend to be petroleum-based.
“These αLA polymer adhesives can be sustainably sourced — as αLA can be bio-manufactured,” said Pal. “Also, they can be recycled in a closed loop system or left to degrade to non-toxic substances.”
Upon stabilizing the αLA polymer, the researchers made small modifications to the underlying monomer composition to optimize the polymers for medical, consumer, and industrial applications. The result was three different products: a medical adhesive formulated to act like a surgical superglue; a pressure-sensitive adhesive, like those used for sticky notes, labels and tape; and an epoxy-like structural adhesive.