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Use of N,N-dimethylaniline end-functional polymers in photoinduced block copolymerization



N,N-Dimethylaniline functional polystyrenes with well-defined structures and low polydispersities were synthesized by atom transfer radical polymerization of styrene in bulk at 110°C using 4-(dimethylamino)benzyl 4-(bromomethyl) benzoate as initiator in conjunction with a cuprous complex [Cu(I)Br/bipyridine]. These polymers were further used in block copolymerization with methyl methacrylate and cyclohexene oxide (CHO) by photoinduced radical and radical-promoted cationic polymerization routes, respectively. In the former case, macroradical generation was achieved with benzophenone sensitizer by photoexcitation followed by hydrogen abstraction from amino end groups. A visible light initiating system was used in the radical-promoted cationic polymerization of CHO. The system involves a xanthene dye (erythrosin B) as the sensitizer, an aromatic N,N-dimethyl amino group and diphenyl iodonium hexafluorophosphate as the radical source and radical oxidizer, respectively. Whereas pure block copolymers were obtained in the free-radical route, the free-radical–promoted cationic polymerization yielded both block and homopolymers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 387–394, 2004