pH- and temperature-sensitive statistical copolymers poly[2-(dimethylamino)ethyl methacrylate-stat-2-vinylpyridine] with Functional succinimidyl-ester chain ends synthesized by nitroxide-mediated polymerization

Statistical copolymerizations of 2-(dimethylamino)ethyl methacrylate (DMAEMA) with 2-vinylpyridine (2VP) with 80 to 99 mol % DMAEMA in the feed utilizing a succinimidyl ester-terminated alkoxyamine unimolecular initiator (NHS-BlocBuilder) at 80 degrees C in bulk were performed. The effectiveness of 2VP as a controlling comonomer is demonstrated by linear increases in number-average molecular weight versus conversion, relatively low PDI (1.51.6 with up to 98% DMAEMA) and successful chain extensions with 2VP. Additional free nitroxide does not significantly improve control for the DMAEMA/2VP copolymerizations. The succinimidyl ester on the initiator permits coupling to amine-terminated poly(propylene glycol) (PPG), yielding an effective macroinitiator for synthesizing a doubly thermo-responsive block copolymer of PPG-block-P(DMAEMA/2VP). A detailed study of the thermo- and pH-sensitivities of the statistical and block copolymers is also presented. The cloud point temperature of the statistical copolymers is fine tuned from 14 to 75 degrees C by varying polymer composition and pH. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012.