Surfacing hydroxyl groups of hyperbranched polyglycerol (PC) were transformed into trithiocarbonates (TTC), an efficient multi radical addition-fragmentation transfer (RAFT) agent, to mediate the polymerization of ethyl acrylate (EA) under controllable conditions, and PC with multiarm PEA was obtained. In this system, PC was a part of Z groups, and trithiolcarbonates were bonded directly to the PG, whereas the growing PEA macroradical was detached. The molecular weight and the Molecular weight distribution of the products were in the range of 1.05-3.24 x 10(4) g/mol and 1.28-1.42, respectively, when the concentration ratio of EA to PG-TTC was 39.8. The number of the PEA arms was about 16. It was found that the measured molecular weights of the products were deviated from the theoretical value, and the molecular weight distribution was broadened with the conversion due to the termination between the leaving macroradicals. The final and the intermediate products were characterized by NMR in detail. (c) 2006 Wiley Periodicals, Inc.