Atom transfer radical copolymerization of N-phenylmaleimide and styrene initiated with dendritic polyarylether 2-bromoisobutyrate

Dendritic polyarylether 2-bromoisobutyrates with different generations (Gn- Br, n = 1-3) were prepared by reaction of the Frechet-type hydroxyl-termina ted polyarylether with 2-bromoisobutyryl bromide and triethylamine. Gn-Br a s a macroinitiator for the controlled free-radical polymerization of N-phen ylmaleimide (PhMI, M-1) and styrene (St, M-2) was investigated. The copolym erization carried out in anisole with CuBr/bpy catalyst afforded polymers w ith well-defined molecular weights and low polydispersities (1.12 < M-w/M-n < 1.35). When the molar fraction of PhMI was 0.50, the apparent activation enthalpy of copolymerization was 38.2 kJ/mol. The effects of monomer feed on the apparent activation enthalpy and copolymer composition were also stu died. The monomer reactivity ratios were determined to be r(1) = 0.0325 and r(2) = 0.0524 according to the Kelen-Tudos method. (C) 2001 John Wiley & S ons, Inc.