Heterofunctional telechelic polymethylene: from precise synthesis to diverse polyolefin-like polymers

Telechelic polyolefins are key building blocks for constructing state-of-the-art polyolefins bearing in-chain functionalities such as ester groups, which have attracted significant attention over recent years. However, the precise synthesis of such α,ω-heterofunctional telechelic polyolefins remains challenging. In this study, polyhomologation is used for the synthesis of α-ester-ω-hydroxy telechelic polymethylenes (bearing hexyl side-chains) through the boron-initiated polyhomologation of ylide monomers. These telechelic polymers are structurally similar to telechelic polyolefins. This method allows for precise control over the end-group fidelity ([OH, COOMe] > 99%) and molecular weight, with particularly narrow molecular weight distributions (Ð = 1.05-1.21) being achieved. Consequently, this approach enables the production of diverse topologies including linear, branched (side-chain), and block structures. Notably, the molecular weight of telechelic polymethylenes was precisely tailored as required. The obtained telechelic polymethylenes serve as AB-type macromonomers and undergo direct polycondensation to afford high-molecular-weight (147-300 kDa) polyolefin-like polymers featuring in-chain ester groups, imparting diverse microstructures and topologies including high-density polyethylene (PE), polyolefin elastomer (POE), and random as well as alternating olefin block copolymers (OBC).