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 (CH 3 CHCO 2 C 2 H 5 )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′  CH 2 CH 3 < CH 2 CF 3 < CHP(O)(OEt) 2 CF 3 . This change in reactivity allowed a lowering of the polydispersity index from 2.0 for Z′  CH 2 CH 3 to 1.15 for Z′  CHP(O)(OEt) 2 CF 3 in the case of the polymerization of styrene. Evolution of M w / M n with conversion during the polymerization of ethyl acrylate in the presence of xanthates X 1 , X 2 and X 3 . Reaction conditions: EA 0 = 4.6 M , X 0 = 5.75 × 10 −2 M , AIBN 0 = 1.72 × 10 −3 M ; T = 80 °C ; solvent: toluene. magnified image Evolution of M w / M n with conversion during the polymerization of ethyl acrylate in the presence of xanthates X 1 , X 2 and X 3 . Reaction conditions: EA 0 = 4.6 M , X 0 = 5.75 × 10 −2 M , AIBN 0 = 1.72 × 10 −3 M ; T = 80 °C ; solvent: toluene.