Accelerated biodegradation of polyurethanes through embedded cutinases

Abstract

Polyurethanes (PUs) are a versatile class of synthetic polymers, which are widely used in foams, coatings, and adhesives. The chemical composition of PUs makes them resistant to biodegradation and causes challenges in applications in which recycling is not an economically viable option, such as plant fixing clips, or tree shelters. A sustainable use in the latter applications requires PU-polymers designed for effective biodegradation with minimized ecological footprints. In this study, a proof of concept for accelerated degradation of biodegradable biocomposite PU materials has been achieved. The PU material was made from thermoplastic PUs (TPUs) and four thermostable cutinases, that were incorporated into industrially important TPUs via melt extrusion at standard TPU processing temperatures up to 200 °C. Embedded cutinases yielded a 37% enzymatic hydrolytic degradation in in vitro studies and biodegradation was accelerated up to ninefold at close to application conditions in activated sludge when compared to virgin TPU. Cutinase-accelerated TPU degradation is a step forward towards a responsible end-of-life waste management within a circular PU economy.