Single-End-Functionalized Polycyclopentene via Ring-Opening Metathesis Polymerization with Concurrent Chain Transfer
journal contributionposted on 17.10.2019, 12:33 by Emily E. Abdo, SeongHyuk Cho, Richard A. Register
Macromonomers bearing a functional group exclusively at one end are often synthesized by terminating a living polymerization with a suitable agent, at the cost of one initiator molecule per chain. An attractive alternative is to use chain transfer to install the functional endgroup. Herein, polycyclopentene (PCP) bearing a single styryl endgroup is synthesized by ring-opening metathesis polymerization 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. A styryl-functional PCP macromonomer copolymerizes effectively with styrene in a free-radical process (styrene reactivity ratio rS ≈ 1.7), producing a comb copolymer with a polystyrene backbone and PCP “teeth”.
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Ring-Opening Metathesis PolymerizationConcurrent Chain Transfer MacromonomersPCP backbonecomb copolymerring-opening metathesis polymerizationstyryl endgroupSingle-End-Functionalized Polycyclopentenechain-transfer stepinitiator moleculepolystyrene backboneHigh regioselectivityfree-radical processendgroup analysisuse chain transferstyryl-functional PCP macromonomer copolymerizeschain-transfer agent