One-Pot Synthesis of Heterograft Copolymers via "Graft Onto" by Atom Transfer Nitroxide Radical Coupling Chemistry

Heterograft copolymers poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl-co- ethylene oxide)-graft-polystyrene and poly(tert-butyl acrylate) (poly (GTEMPO-co-EO)-g-PS/PtBA) were synthesized in one-pot by atom transfer nitroxide radical coupling (ATNRC) reaction via "graft onto." The main chain was prepared by the anionic ring-opening copolymerization of ethylene oxide (EO) and 4-glycidyloxy2,2,6,6-tetramethylpiperidine-1-oxyl (GTEMPO) first, then the polystyrene and poly (tert-butyl acrylate) with bromine end (PS-Br, PtBA-Br) were prepared by atom transfer radical polymerization (ATRP). When three of them were mixed each other in the presence of CuBr/N,N,N',N",N"-pentamethyldiethylenetriamine (PMDETA) at 90 degrees C, the formed secondary carbon radicals at the PS and PtBA chain ends were quickly trapped by nitroxide radicals on poly(GTEMPO-co-EO). The heterograft copolymers were well defined by H-1 NMR, size exclusion chromatography, fourier transform infrared, and differential scanning calorimetry in detail. It was found that the density of GTEMPO groups on main chain poly(GTEMPO-co-EO), the molecular weights of PS/PtBA side chains, and the structure of macroradicals can exert the great effects on the graft efficiency. (c) 2008 Wiley Periodicals, Inc.