Synthesis of comb‐branched polyacrylamide with cationic poly[(2‐dimethylamino)ethyl methacrylate dimethylsulfate] quat

Abstract Comb‐branched polyelectrolytes with polyacrylamide backbones and poly[(2‐dimethylamino)ethyl methacrylate methylsulfate] (polyDMAEMA‐DMS) side chains were prepared by free‐radical macromonomer polymerization. PolyDMAEMA‐DMS macromonomers bearing terminal styrenic moieties were synthesized by living anionic polymerization with lithium 4‐vinylbenzylamide (LiVBA) and lithium N ‐isopropyl‐4‐vinylbenzylamide (LiPVBA) as initiators. In the presence of LiCl, LiPVBA initiated a living polymerization of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) and produced polymers with well‐controlled molecular weights and low polydispersities. LiVBA could not directly initiate DMAEMA polymerization. After being capped with two units of dimethylacrylamide, DMAEMA polymerized with an initiator efficiency of 63%. The quaternization of the poly[(2‐dimethylamino)ethyl methacrylate] macromonomer with dimethyl sulfate yielded the cationic polyDMAEMA‐DMS macromonomer. The polyDMAEMA‐DMS macromonomer had a much higher reactivity than acrylamide in free‐radical polymerization. This might have been due to the formation of polyDMAEMA‐DMS micelles in the polymerization system. The high macromonomer reactivity caused composition drift in a batch process. A semibatch method with a constant polyDMAEMA‐DMS feed rate was used to control the copolymer composition. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2394–2405, 2002