H-shaped ABCAB terpolymers composed of polystyrene (PS) (A), poly (ethylene oxide) (PEO) (B), and poly(tert-butyl acrylate) (PtBA) (C) were prepared by atom transfer radical coupling reaction using ABC star terpolymers as precursors, CuBr and N,N,N',N '',N ''-pentamethyldiethylenetriamine (PMDETA) as catalysts, and nanosize copper as the reducing agent. The synthesis of 3-miktoarm star terpolymer PS-PEO-(PtBA-Br) involved following steps: (1) the preparation of PS with an active and an ethoxyethyl-ptotected hydroxyl group at the same end; (2) the preparation of diblock copolymer PS-b-PEO with ethoxyethyl-protected group at the junction point through the ring-opening polymerization (ROP) of EO; (3) after de-protection of ethoxyethyl group and further modification of hydroxyl group, tBA was polymerized by atom transfer radical polymerization using PS-b-PEO with 2-bromoisobutyryl functional group as macroinitiator. The H-shaped terpolymer could be successfully formed by atom transfer radical coupling reaction in the presence of small quantity of styrene, CuBr/PMDETA, and Cu at 90 degrees C. The copolymers were characterized by SEC, H-1 NMR, and FTIR in detail. The optimized coupling temperature is 90 degrees C. (c) 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 59-68, 2009