Neural network finds an enzyme that can break down polyurethane

"You'll often hear plastic pollution referred to as a problem. But the reality is that it's multiple problems. Depending on the properties we need, we form plastics out of different polymers, each of which is held together by a distinct type of chemical bond. So the method we use to break down one type of polymer may be incompatible with the chemistry of another."

"That problem is why, even though we've had success finding enzymes that break down common plastics like polyesters and PET, they're only partial solutions to plastic waste. However, researchers aren't sitting back and basking in the triumph of partial solutions, and they've now got very sophisticated protein design tools to help them out. That's the story behind a completely new enzyme that researchers developed to break down polyurethane, the polymer commonly used to make foam cushioning, among other things."

"The new paper that describes the development of this enzyme lays out the scale of the problem: In 2024, we made 22 million metric tons of polyurethane. The urethane bond that defines these involves a nitrogen bonded to a carbon that in turn is bonded to two oxygens, one of which links into the rest of the polymer. The rest of the polymer, linked by these bonds, can be fairly complex and often contains ringed structures related to benzene."

A completely new enzyme was developed to break down polyurethane and is compatible with an industrial-style recycling process that depolymerizes the material into its basic building blocks usable to form fresh polyurethane. Polyurethanes totaled about 22 million metric tons produced in 2024. The urethane bond involves a nitrogen bonded to a carbon that is bonded to two oxygens, one linking into the polymer; the polymer often includes complex, benzene-related ring structures. Extensive cross-linking and bulky structures hinder enzymatic access. Diethylene glycol can partially depolymerize polyurethanes only at elevated temperatures and leaves behind complex wastes typically incinerated as hazardous material.

Read at Ars Technica