Well-defined highly branched comb-like polystyrenes (PS) having one branch in each repeating unit have been successfully synthesized by the coupling reaction of living PS anions with 1,1-diphenylethenyl (DPE) groups along PS backbone prepared via atom transfer radical polymerization. When excess polystyryllithium (PSLi) was used, the quantitative grafting efficiency was achieved. The resulting polymers were characterized by NMR, IR, GPC, and SLS in detail. (c) 2005 Elsevier Ltd. All rights reserved.