A series of new well-defined nanoparticles containing an organotin core and a polystyrene shell were obtained by crosslinking of n-Bu2SnO with various chain-length amphiphilic polystyrene-b-poly-(6-(4-vinylphenoxy) hexanoic acid. The amphiphilic copolymers were synthesized via reversible addition fragmentation chain transfer polymerization and hydrolysis. The structures of the nanoparticles were studied by the transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy analysis. Notably, the morphology of the crosslinked copolymer showed individual nanoparticles with regularly spherical shape. And the nanoparticle diameters decreased with increasing number of organotin carboxylate units. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012