Lipase-Driven Deconstruction of Polyether Polyurethane Foams through Alcoholysis toward a Closed-Loop Recycling

Polyether polyurethane foams are widely used materials in everyday life, yet they are highly recalcitrant and difficult to recycle. Until now, no efficient bioprocess currently exists for their depolymerization. Lastly, the use of enzymes has revolutionized plastic recycling, but their application to polyurethanes remains in its infancy. In this work, we selected some enzymes capable of cleaving urethane bonds through alcoholysis, a mechanism that goes beyond conventional enzymatic hydrolysis. Among them, two lipases from Thermomyces lanuginosus and Rhizopus oryzae proved particularly promising when using methanol and ethanol as reaction agents. These enzymes successfully degraded polyether polyurethane foams, releasing polyols and alkyl carbamates. The recovered polyols could be isolated and subsequently reused in a new polymerization process, generating partially recycled foams. This enzymatic solvolysis approach in alcohol media was extended to non-isocyanate polyurethane foams, opening new paths for depolymerizing and recycling complex plastics, thereby contributing to a more circular plastic economy.