The macroinitiator of a copolymer (PMDBTM) of methyl methacrylate (MMA) and 2-(dimethylamino)ethyl methacrylate (DAMA) with 4-benzyloxy-2,2,6,6-tetramethyl- 1-piperidinyloxy (BTEMPO) pendant groups was prepared by the photochemical reaction of tertiary amine groups of the copolymer with benzophenone in the presence of BTEMPO. The radical copolymerization of MMA and DAMA was carried out first with azo-bis-isobutyronitrile (AIBN) as an initiator; then, the dimethylamine groups of the copolymer constituted a charge-transfer complex with benzophenone under UV irradiation, and the methylene of ternary amine and diphenyl methanol radicals were produced. The former was capped by BTEMPO, and the nitroxide (BTEMPO) was attached to the polymeric backbone. The amount of pendant BTEMPO on PMDBTM was measured by H-1 NMR. PMDBTM initiated the graft polymerization of styrene via a controlled radical mechanism, and the molecular weight of the PMD-g-polystyrene increased with the polymerization time. (C) 2001 John Wiley & Sons, Inc.