Preparation of high capacity weak base poly(methyl methacrylate)-ethylene glycol dimethylacrylate copolymer anion exchange resin by modification using NOx

Abstract

Macroporous poly(methyl methacrylate)–ethylene glycol dimethylacrylate (PMMA–EGDM) resin (resin 1) was prepared by suspension polymerization and gelatin was found to be the key component deciding the size of particles. To prepare aminated macroporous weak base PMMA–EGDM exchanger, resin 1 was nitrated using NO2 gas with a minor amount of NO (termed NOx). The modified PMMA–EGDM resin (resin 2) was reduced to NH2 groups and the exchange capacity of the weak base anion exchange resin (resin 3) was determined. Regression analysis of NOx consumption versus time and the exchange capacity Q versus time data suggested a second-order kinetics for the modification reaction and these are reported. We examined the effect of duration of nitration on the exchange capacity of resin 3. It was found that it first increased with the increase in the extent of nitration, reaching a broad maximum of 4.8 meq/g of wet resin with 78% moisture for about 8 h of nitration, and decreasing for longer nitration times as a result of polymer degradation. These results were compared with commercial resin, which had an exchange capacity of 1.68 meq/wet g with 43% moisture content. To assess the salvation ability of the modified PMMA–EGDM resin, consistent with the literature, we devised three stages of removing moisture. Experiments suggest that the high capacity of the modified PMMA–EGDM resin may be attributed to this increased salvation ability. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1991–1999, 2003