Synthesis of hydroxyethylcellulose‐graft‐poly(N,N‐dimethylacrylamide) copolymer by ATRP and as dynamic coating in capillary electrophoresis

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 (Me₆[14]aneN₄) as catalyst and ligand, with molar ratio DMA: HEC‐Br (C? Br): CuBr: Me₆[14]aneN₄ = 100 : 1 : 1 : 3. HEC–Br macroinitiator was synthesized by esterification of HEC with 2‐bromoisobutyryl bromide. GPC and ¹H 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. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010