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 < CH[P(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′  CH[P(O)(OEt)2]CF 3 in the case of the polymerization of styrene. Evolution of Mw/Mn 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 imageEvolution of Mw/Mn 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.