We describe the synthesis of diblock and triblock copolymers by sequential atom transfer radical polymerization of styrene and acetoxymethylstyrene. Contrary to the usual block copolymerization involving isolation of the macroinitiator, a convenient one-pot procedure is developed. This is possible because of the preferential polymerization of acetoxymethylstyrene, even in the presence of residual styrene, ay inferred from characterization of the intermediate polystyrenes and the block copolymers by size exclusion chromatography, H-1 NMR, Fourier transform infrared spectroscopy, differential scanning calorimetry, and GPEC techniques. The latent acetoxy functionalities in these block copolymers are shown to be easily unmasked to -OH and -Br functionalities, with the potential for block ionomers and dense graft, architectures. (C) 2004 Wiley Periodicals, Inc.