Summary: Application of high pressure, up to 2 500 bar, in cumyl dithiobenzoate‐mediated styrene reversible addition fragmentation chain transfer (RAFT) polymerizations was found to be extremely advantageous with respect to both rate and control of polymerization. The overall rate of polymerization could be increased by a factor of approximately 3 with, e.g., at 23% conversion, concomitantly reducing the polydispersity indices from 1.35 to 1.10. No significant effect of increased pressure on the rate retardation effect was found.
SEC curves of polystyrene samples with identical peak molecular weights, generated by CDB‐mediated styrene bulk polymerization at 70 °C at 1 and at 2 000 bar.
