Well-defined sulfonated polystyrene and block copolymers with n-butyl acrylate (nBA) were synthesized by CuBr catalyzed living radical polymerization. Neopentyl p-styrene sulfonate (NSS) was polymerized with ethyl-2-bromopropionate initiator and CuBr catalyst with N,N,N',N'-pentamethylethyleneamine to give poly(NSS) (PNSS) with a narrow molecular weight distribution (MWD < 1.12). PNSS was then acidified by thermolysis resulting in a polystyrene backbone with 100% sulfonic acid groups. Random copolymers of NSS and styrene with various composition ratios were also synthesized by copolymerization of NSS and styrene with different feed ratios (MWD < 1.11). Well defined block copolymers with nBA were synthesized by sequential polymerization of NSS from a poly(n-butyl acrylate) (PnBA) precursor using CuBr catalyzed living radical polymerization (MWD < 1.29). (C) 2008 Wiley Periodicals, Inc.