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 (Me 6 [14]aneN 4 ) as catalyst and ligand, with molar ratio DMA: HEC‐Br (CBr): 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 1 H 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