Atom transfer radical polymerization (ATRP) was applied to synthesize a new kind of star polymers of hyperbranched polyglycerol (HPG) core with multiarms of PS-b-PtBA and PS-b-PAA by using the "core first" technique. The HPG core was obtained by anionic polymerization of glycerol first, and then the pendant hydroxyl groups of HPG were esterified with 2-bromoisobutyryl bromide to yield the HPG-g-Br, which was used as macroinitiator for ATRP of the first monomer (St) and then second monomer (tBA). After hydrolysis of the PtBA block, poly(acrylic acid) (PAA) side chains were formed. The final products and intermediates were characterized by GPC, NMR, and FTIR in detail. (c) 2008 Wiley Periodicals, Inc.