Star-Like PAA-g-PPO Well-Defined Amphiphilic Graft Copolymer Synthesized by ATNRC and SET-NRC Reaction

A series of well-defined amphiphilic star graft copolymers consisting of hydrophilic poly(acrylic acid) backbone and hydrophobic poly(propylene oxide) side chains were synthesized by the sequential reversible addition-fragmentation chain transfer (RAFT) polymerization and atom transfer nitroxide radical coupling (ATNRC) or single electron transfer-nitroxide radical coupling (SET-NRC) reaction followed by the selective hydrolysis of poly(tert-butyl acrylate) backbone. A Br-containing acrylate monomer, tert-butyl 2-((2-bromopropanoyloxy)methyl)acrylate, was first homopolymerized via RAFT polymerization using a new star-like chain-transfer agent with four arms in a controlled way to give a well-defined star-like backbone with a narrow molecular weight distribution (M-w/M-n = 1.231. The grafting-onto strategy was used to synthesize the well-defined PtBA-g-PPO star graft copolymers with narrow molecular weight distributions (M-w/M-n = 1.14-1.25) via ATNRC or SET-NRC reaction between the Br-containing PtBA-based star-like backbone and poly(propylene oxide) with 2,2,6,6-tetra-methylpiperidine-1-oxyl end group using CuBr/PMDETA or Cu/PMDETA as catalytic system. PAA-g-PPO amphiphilic star graft copolymers were obtained by the selective acidic hydrolysis of star-like PtBA-based backbone in acidic environment without affecting the side chains. The critical micelle concentrations in aqueous media and brine were determined by the fluorescence probe technique. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2084-2097, 2010