Circular olefin copolymers made de novo from ethylene and α-olefins

Polyethylene (PE)-based materials, including ethylene homopolymers and its random or block copolymers with α-olefins, are the most produced synthetic materials globally, but current practices in their production, use, and after-use that follow the linear materials economy framework have taken a huge toll on both the environment and society. 1,2 Although several notable advances have been made in PE chemical re/upcycling, 3-10 energy-efficient and selective catalytic processes are still lacking due to the inherent chemical inertness of C-C and C-H bonds in PE. 11 Ideally, PE materials should be made de novo to have a circular, closed-loop lifecycle. 12-15 Recently, several circular polymers with closed-loop lifecycles were developed, 16-22 including recyclable high-density PE (HDPE)-like polymers. 23-25 However, production of circular ethylene/α-olefin copolymers, including high-volume, linear low-density PE (LLDPE) as well as high-value olefin elastomers and block copolymers at scale, presents a particular challenge due to difficulties in introducing branches while simultaneously installing chemical recyclability and also directly using industrial ethylene and α-olefin feedstocks. Here we show that coupling of industrial coordination copolymerization of ethylene and α-olefins with a designer functionalized chain-transfer reagent, followed by modular assembly of the resulting AB telechelic polyolefin building blocks by polycondensation, affords a series of ester-linked LLDPE and PE-based copolymers. These new materials not only retain thermomechanical properties of PE-based materials but also exhibit full chemical circularity via simple transesterification and markedly enhanced adhesion to polar surfaces.