Effects of Br Connected Groups on Atom Transfer Nitroxide Radical Coupling Reaction and Its Application in the Synthesis of Comb-Like Block Copolymers

The effects of Br connected groups on atom transfer nitroxide radical coupling (ATNRC) reaction were investigated. Two precursors methoxyl poly(ethylene oxide)-b-poly(ethylene oxide-co-2-bromoiso butyryloxy glycidyl ether) (mPEO-b-Poly(EO-co-BiBGE)) and methoxyl poly(ethylene oxide)-b-poly(2-bromoiso butyryloxy glycidyl ether) (mPEO-b-Poly(BiBGE)) with different -C(CH3)(2)Br density were designed and synthesized firstly, and then ATNRC reaction were completed between these precursors and 2,2,6,6-tetramethylpiperidinyl-1-oxy poly(epsilon-caprolactone) (TEMPO-PCL) in the presence or absence of St monomers, respectively. The results showed that the structure of Br connected groups showed an important effect on ATNRC reaction, and the ATNRC reaction with high efficiency could be realized by transforming the higher active Br connected groups into the lower one by the addition of small amount of St monomers. The final comb-like block copolymers mPEO-b-[Poly(EO-co-Gly)-g-(St(1.8)-b-PCL)] and mPEO-b-[Poly(Gly)-g-(St(2.4)-b-PCL)] with high coupling efficiency were obtained by this strategy. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48:16331640, 2010