Xanthates as chain-transfer agents in controlled radical polymerization (MADIX): Structural effect of the O-alkyl group

Abstract : The capability of three chain-transfer agents, O-alkyl-S-(1-ethoxycarbonyl)ethyl xanthates (CH3-CHCO2C2H5)S(C=S)OZ', to control the free-radical polymerization of styrene and ethyl acrylate by the MADIX process was examined. The reactivity of the xanthates varied according to the following trend: Z' = CH2CH3 < CH2CF3 < CH[P(O)(OEt)2]CF3. This change in reactivity allowed a lowering of the polydispersity index from 2.0 for Z' = CH2CH3 to 1.15 for Z' = CH[P(O)(OEt)2]CF3 in the case of the polymerization of styrene.