关键词: 原子转移自由基聚合, 双官能引发剂, 嵌段共聚物

Abstract: Ethyl α,α-dibromoacetate was confirmed to be a difunctional initiator for the atom transfer radical polymerization of n-butyl acrylate by means of gel penetration chromatography. When the polymerization of n-butyl acrylate was carried out aTdifferent molar ratios of ethyl α,α-dibromoacetate and ethyl α bromopropionate with CuBr/2,2′-bipyridine as the catalyst, polymers with bimodal molecular weigh Tdistributions were obtained, consisting of two narrowly distributed fractions, one of which was of a molecular weigh Td ouble the other. Poly( n-butyl acrylate) obtained with ethyl α,α-dibromoacetate as the difunctional initiator was further used as the macroinitiator for styrene and methyl methacrylate in the presence of CuBr/2,2′-bipyridine respectively to prepare ABAtriblock copolymers. It was found that high blocking efficiency was obtained for styrene. However, the polymer with bimodal molecular weighTdistribution was obtained for methyl methacrylate with a low molecular weight peak corresponding to that of poly( n-butyl-acrylate) macroinitiator. If the blocking polymerization was conducted with CuCl/ 2,2′-bipyridine as the catalyst to replace CuBr/2,2′-bipyridine, a high blocking efficiency was also obtained.

Key words: Atom transfer radical polymerization, Difunctional initiator, Block copolymer