Cyclopentene (CP) can be polymerized in a living fashion by ring-opening metathesis polymerization (ROMP) with suitable initiators, and subsequently hydrogenated to perfectly linear polyethylene (PE). End-functional PE precursors can be synthesized via termination with a suitable agent, but this comes at the cost of one initiator molecule per chain, as for any living polymerization. An attractive alternative is to use chain transfer to install the functional endgroup. Polycyclopentene (PCP) bearing a single styryl endgroup is synthesized by ROMP with a well-defined Mo-based (Schrock) initiator, by employing divinylbenzene as a chain transfer agent. High regioselectivity of the chain transfer step, with minimal secondary metathesis of double bonds in the PCP backbone, is confirmed by mass spectral endgroup analysis. This styryl-functional PCP macromonomer copolymerizes effectively with styrene in a free-radical process (styrene reactivity ratio 1.7), producing a comb copolymer with a polystyrene backbone and PCP “teeth” (which can be converted to PE by hydrogenation).

Synthesis of end-functional polyethylene precursors and comb copolymers by cyclopentene ROMP with regioselective chain transfer

ACS Spring Meeting 2021

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