Aqueous solution properties of pH-responsive AB diblock acrylamido-styrenic copolymers synthesized via aqueous reversible addition-fragmentation chain transfer

Here we report the synthesis and solution characterization of a novel series of AB diblock copolymers with neutral, water-soluble A blocks consisting of N,N-dimethylacrylamide and pH-responsive B blocks of N,N-dimethylvinylbenzylamine. To our knowledge, this represents the first example of an acrylamido-styrenic block copolymer prepared directly in a homogeneous aqueous solution. The best blocking order [with poly(N,N-dimethylacrylamide) as a macro-chain-transfer agent] yielded well-defined block copolymers with minimal homopolymer impurities. The reversible aggregation of these block copolymers in aqueous media was studied with H-1 NMR spectroscopy and dynamic light scattering. Finally, an example of core-crosslinked micelles was demonstrated by the addition of a difunctional crosslinking agent to a micellar solution of the parent block copolymer. (C) 2004 Wiley Periodicals, Inc.