Effects of poly(vinyl pivalate)-based stabiliser architecture on CO₂-solubility and stabilising ability in dispersion polymerisation of N-vinyl pyrrolidone

We report the comparison of block and statistical copolymers of poly(vinyl pivalate) (PVPi), synthesised via RAFT polymerisation, as hydrocarbon stabilisers for use in dispersion polymerisations in CO₂. Block copolymer stabilisers are synthesised, and their relative effectiveness in terms of solubility and stabilising ability is compared to statistical copolymer equivalents. The effect of stabiliser molecular weight on dispersion polymerisation of poly(N-vinyl pyrrolidone) PNVP in scCO₂ is also explored. Finally, the RAFT end-group incorporated into the stabiliser is completely removed using radical-induced reduction to produce a hydrogen-capped stabiliser in order to investigate the significance of the xanthate in the final stabiliser structure, and whether this component plays a key role in anchoring to the growing polymer particles in scCO₂.