Biorenewable and circular polyolefin thermoplastic elastomers.

Polymers capable of depolymerizing back to their own monomers offer a promising solution to address the challenges in polymer sustainability. Despite significant progress has been achieved in plastics circularity, chemical recycling of thermoplastic elastomers is relatively less concerned, largely because of their intrinsic complex multicomponents. This work creates a homopolymer-based platform towards chemically recyclable but tough thermoplastic elastomers. It is enabled by a semicrystalline polymer with high molecular weight but low crystallinity, which is prepared through ring-opening metathesis polymerization of a fully biobased cyclic olefin. By shifting the ring-chain equilibrium, quantitative conversions were achieved for both forward polymerization and reverse depolymerization. This simple circular, high-performance thermoplastic elastomer platform based on biomass highlights the importance of monomer design in addressing three challenges in sustainable polymers: the feedstock renewability, depolymerization selectivity, and performance trade-offs.