Aoshima Sadahito, Oda Yukari, Matsumoto Suzuka, Shinke Yu, Kanazawa Arihiro, Kanaoka Shokyoku
Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
ACS Macro Lett. 2014 Jan 21;3(1):80-85. doi: 10.1021/mz400563v. Epub 2013 Dec 30.
Specifically designed alternating cationic copolymerization produced well-defined thermo- or pH-responsive polymers with complete acid-degradability. For example, a thermosensitive alternating copolymer with acid-labile acetal linkages in the main chain was obtained from the controlled cationic copolymerization of -methoxybenzaldehyde (pMeOBzA) and a vinyl ether (VE) with an oxyethylenic side chain. The resulting copolymer exhibited a sharp thermosensitive phase transition in water. The same strategy but using different VEs with esters and benzaldehyde (BzA) yielded pH-responsive copolymers with nearly alternating sequences and narrow molecular weight distributions (MWDs). The alternately arranged acetal bonds in the copolymers allowed complete facile and rapid degradation under acidic conditions, which selectively produced low-molecular-weight compounds (MW ∼ 1-2 × 10).
