Synthesis and characterization of rigid functional anionic polyelectrolytes: Block copolymers and star homopolymers

Seven cyclolinear polymers bearing the tertiary-butyl a-(hydroxymethyl)acrylate (TBHMA) ether dimer were prepared using reversible additionfragmentation chain transfer (RAFT) polymerization. Of the seven polymers, five were cyclolinear homopolymers of the TBHMA ether dimer with different degrees of polymerization, one was an arm-first star homopolymer, and the other was an amphiphilic linear copolymer based on the positively ionizable hydrophilic 2-(dimethylamino)ethyl methacrylate (DMAEMA) and the TBHMA ether dimer. For comparison, two more polymers were prepared using RAFT polymerization where the TBHMA ether dimer was replaced by tertiary-butyl methacrylate (tBuMA). In particular, an amphiphilic linear DMAEMAtBuMA diblock copolymer and a tBuMA arm-first star homopolymer were also synthesized. All polymers were characterized in terms of their molecular weights and composition using gel permeation chromatography and H-1 NMR spectroscopy, respectively. Subsequently, the tertiary-butyl groups of the TBHMA ether dimer units and those of the tBuMA units were cleaved by hydrolysis to yield carboxylic acid groups. The successful removal of the tertiary-butyl groups was confirmed using H-1 and C-13 NMR and attenuated total reflectance-Fourier transform infrared spectroscopies. The hydrolyzed (co)polymers exhibited pK values of the carboxylic acid groups of around 4.5, and glass transition temperatures, T-g, of around 200 degrees C, which were 50 degrees C higher than those of their nonhydrolyzed precursors. (c) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 665-674, 2012