Controlled radical alternating copolymerization of N ‐phenyl maleimide with ethyl α‐ethylacrylate by reversible addition fragmentation chain‐transfer process

The alternating copolymerization of N ‐phenyl maleimide (NPMI) with ethyl α‐ethylacrylate (EEA) by the reversible addition fragmentation chain‐transfer process was investigated. The monomer reactivity ratios were measured and r 1 = 0.19 ± 0.03 for NPMI and r 2 = 0.20 ± 0.04 for EEA. It was found that before about 45% of the comonomer conversion, the molecular weight of the copolymer increased with the conversion, the molecular weight distribution was rather narrow, and the molecular weight of the copolymer approached a constant value, irrespective of the length of the polymerization time. Electronic spin resonance determined that the radical signal disappeared quickly after the conversion of comonomer exceeded 45%, which may be attributed to the coupling termination of the propagating polymer chains with the EEA end with the intermediate radicals when the concentration of comonomers decreased. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2376–2382, 2004