Graft copolymer of cellulose diacetate (CDA) and PMMA was synthesized through atom transfer radical polymerization (ATRP). The residual hydroxyl groups on the diacetate cellulose reacted with 2-bromoisobutyryl bromide to yield 2-bromoisobutyryl groups known to be an efficient initiator for ATRP. Then the functional CDA was used as macroinitiator in the ATRP of MMA. The polymerization was carried out in the system of PMDETA/CuBr/1,4-dioxane under 70 degreesC. Kinetic study indicated that the polymerization is first order. Copolymers were characterized by H-1 NMR and GPC. The molecular weight increased without any trace of the macroinitiator, and the polydispersities were low. (C) 2004 Published by Elsevier Ltd.