Convenient Synthesis of Thermo-Responsive PtBA-g-PPEGMEMA Well-Defined Amphiphilic Graft Copolymer Without Polymeric Functional Group Transformation

A series of well-defined amphiphilic graft copolymers bearing hydrophobic poly(tert-butyl acrylate) backbone and hydrophilic poly[poly(ethylene glycol) methyl ether methacrylate)] (PPEGMEMA) side chains were synthesized by sequential reversible addition fragmentation chain transfer (RAFT) polymerization and single-electron-transfer living radical polymerization (SET-LRP) without any polymeric functional group transformation. A new Br-containing acrylate monomer, tert-butyl 2-((2-bromoisobutanoyloxy)methyl)acrylate (tBBIBMA), was first prepared, which can be homopolymerized by RAFT to give a well-defined PtBBIBMA homopolymer with a narrow molecular weight distribution (M-w/M-n 1.15). This homopolymer with pendant Br initiation group in every repeating unit initiated SET-LRP of PEGMEMA at 45 degrees C using CuBr/dHbpy as catalytic system to afford well-defined PtBBIBMA-g-PPEGMEMA graft copolymers via the grafting-from strategy. The self-assembly behavior of the obtained graft copolymers in aqueous media was investigated by fluorescence spectroscopy and TEM. These copolymers were found to be stimuli-responsive to both temperature and ions. Finally, poly(acrylic acid)-g-PPEGMEMA double hydrophilic graft copolymers were obtained by selective acidic hydrolysis of hydrophobic PtBA backbone while PPEGMEMA side chains kept inert. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 3328-3337, 2011