Upcycling of Post-Consumer Polycaprolactone to Polyamides and Poly(ester amide)s via Aminolysis-Dehydrogenative Polymerization.

Upcycling waste polyesters into valuable materials to address plastic pollution and reduce the waste of carbon resources is a necessary and highly challenging task. Herein, we present an "aminolysis-dehydrogenative polymerization" strategy that enables one-pot upcycling of polycaprolactone (PCL) into polyamides (PAs) and poly-(ester amide)-s (PEAs) in high yields with controllable ester-to-amide ratios and tunable functional moieties. Detailed mechanism analysis elucidates that the process involves four kinds of reactions: aminolysis, dehydrogenative cross-coupling of amine and alcohol, transesterification, and dehydrogenative self-coupling of alcohol. Significantly, the upcycling of post-consumer PCL into PAs and PEAs is also achieved, demonstrating a strong industrial application potential of this approach.