Hyperbranched polystyrenes (HPS) were prepared by living radical polymerization of 4-vinylbenzyl N,N-diethyldithiocarbamate (VBDC) as an inimer under UV irradiation. These HPS exhibited large amounts of photofunctional diethyldithiocarbamate (DC) groups On their outside Surfaces. We derived star-HPS (SHPS) by grafting from such HPS macroinitiator with methyl methacrylate (MMA) or ethyl methacrylate (EMA). The ratios of radius of gyration to hydrodynamic radius R-g/R-h for HPS and SHPS in tetrahydrofuran (THF) were in the range of 0.74-0.90 and 1.05-1.12, respectively. HPS and SHPS behaved in a good solvent as hard and soft spheres, respectively. We demonstrated the structural ordering of both branched polymers in THF through small-angle X-ray scattering (SAXS), by varying the polymer concentration. As a result, HPS and SHPS formed face-centered-cubic (fcc) and body-centered-cubic (bcc) structures, respectively, near the overlap threshold (C*). (c) 2006 Wiley Periodicals, Inc.