Exploring high molecular weight vinyl ester polymers made by PET-RAFT

Polyvinyl esters have wide range of applications; however, the synthesis of high molecular weight uniform polymers is an ongoing challenge. Vinyl ester monomers are among the less activated monomers compatible with RAFT polymerization. The highly reactive unconjugated radicals formed during propagation are prone to side reactions, especially irreversible transfer, limiting the evolution of molecular weight and control over molecular weight distribution. Herein, the effect of monomer type on the control of polyvinyl esters synthesized by photoinduced electron/energy transfer reversible addition-fragmentation chain transfer polymerization (PET-RAFT) is explored. We show that PET-RAFT is capable of forming high molecular weight polyvinyl esters (vinyl pivalate: M-n > 350 000 and vinyl acetate: M-n > 80 000) under mild conditions. The livingness of the polymerization was determined by following chain extensions for low and high chain length systems.