Macromolecular Design via the Interchange of Xanthates (MADIX): Polymerization of styrene with O-ethyl xanthates as controlling agents

A series of eight xanthates of the general structure R-S(C=S)OEt as reversible addition fragmentation chain-transfer agents to achieve the control of free-radical polymerization of styrene. The influence of the nature of R leaving group was also explored. It was found that the transfer ability of the xanthate is markedly improved with increasing stability of R and its steric hindrance. The cyanoisopropyl group was shown to the best group, leading to an increase in the molecular weight during polymerization that was close to linearity. A zero-order dependence of the kinetics of polymerization on the xanthate concentration was also observed.