A series of well-defined amphiphilic graft copolymers bearing hydrophilic poly(ethylene oxide) (PEO) side chains with tunable grafting densities were synthesized by atom transfer nitroxide radical coupling (ATNRC) reaction using CuBr/PMDETA as catalytic system via the grafting-onto strategy. PEO side chains were linked to a-C of carbonyl of polyacrylate-based backbone, not to the ester side groups as usual, so that every repeating unit of the backbone possessed a pendant steric bulky tert-butyl group. The critical micelle concentrations of the obtained amphiphilic graft copolymers in aqueous media determined by fluorescence probe technique using pyrene as probe increased with the raising of molecular weights. These amphiphilic graft copolymers with novel chemical structure showed unprecedented diverse nanostructures visualized by transmission electron microscopy in aqueous media and micellar morphologies varied with the changing of experiment parameters. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012