Amphiphilic block copolymers of methyl methacrylate (MMA) and sodium styrene sulfonate (SSNa) were successfully synthesized via direct atom transfer radical polymerization (ATRP) of SSNa. First, poly(sodium styrene sulfonate) (PSSNa) or poly(methyl methacrylate) (PMMA) macroinitiators; were prepared using proper ATRP systems for each case. In some cases, functional initiators, which allow further reactions, were used. The macroinitiators; were characterized and further used to synthesize PSSNa/PMMA block copolymers, by using proper solvent combinations, such as N,N-dimethylformamide/water or methanol/water at appropriate volume ratios, in order to ensure solubility of the synthesized amphiphilic copolymers. The molecular weight of the copolymers was determined by gel permeation chromatography, using water as eluent. By using a combination of analytical techniques like H-1 NMR, FTIRand thermogravimetry, the chemical structure and the actual copolymer composition were determined. Since, the block copolymers were soluble in water, forming hydrophilic/hydrophobic domains in aqueous solution, their micellization behavior was further studied by pyrene fluorescence probing. (C) 2008 Elsevier Ltd. All rights reserved.