Hydroxyethylcellulose-graft-poly (N, N-dimethylacrylamide) was synthesized by successive atom transfer radical polymerization (ATRP) of N,N-dimethylacrylamide (DMA) monomer using HEC-Br as initiator, CuBr and 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazamacrocyclotetradecane (Me-6[14]aneN(4)) as catalyst and ligand, with molar ratio DMA: HEC-Br (C-Br): CuBr: Me-6[14]aneN(4) = 100 : 1 : 1 : 3. HEC-Br macroinitiator was synthesized by esterification of HEC with 2-bromoisobutyryl bromide. GPC and H-1 NMR studies show that the molecular weight of the resulting PDMA increased linearly with the conversion. Within 6 h, the polymerization can reach almost 60% of conversion. The copolymer is applied for the separation of basic proteins in capillary electrophoresis. The results show that this medium has a powerful capability in resisting basic proteins adsorption because the polymer forms noncovalent coating in silica capillaries. With a broad range of pH 2-7, proteins were separated with sufficient efficiencies above 200,000 plates/m. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 116: 3468-3472, 2010