Comb-branched polyelectrolytes with polyacrylamide backbones and poly[(2-dimethylamino)ethyl methacrylate methylsulfate] (polyDMAEMA-DMS) side chains were prepared by free-radical macromonomer polymerization. PolyDMAENTA-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 1-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.