The star graft copolymers composed of hyperbranched polyglycerol (HPG) as core and well defined asymmetric mixed "V-shaped" identical polystyrene (PS) and poly(tert-butyl acrylate) as side chains were synthesized via the "click" chemistry. The V-shaped side chain bearing a "clickable" alkyne group at the conjunction point of two blocks was first prepared through the combination of anionic polymerization of styrene (St) and atom transfer radical polymerization of tert-butyl acrylate (tBA) monomer, and then "click" chemistry was conducted between the alkyne groups on the side chains and azide groups on HPG core. The obtained star graft copolymers and intermediates were characterized by gel permeation chromatography (GPC), GPC equipped with a multiangle laser-light scattering detector (GPC-MALLS), nuclear magnetic resonance spectroscopy and fourier transform infrared. (C) 2009 Wiley Periodicals, Inc. J Polym, Sci Part A: Polym Chem 47: 1308-1316, 2009