Synthesis and characterization of a cation-exchange resin based on vinylpyrrolidone-co-divinylbenzene:: Effect of nature and amount of diluent on different resin properties

Fundamental studies regarding the synthesis of a porous copolymer synthesized from 1-vinyl-2-pyrrolidone and divinylbenzene in the presence of different diluents were carried out. A series of porous copolymer resins was synthesized by suspension polymerization using the following diluents: dimethylphthalate (DMT), diethylphthalate, dibutylphthalate, and bis-2-ethyl hexylphthalate [dioctylphthalate (DOT)]. It was observed that the porosity of resin increases with increase in length of the methylene group in the phthalate ester of DMT to DOT. In another series of experiments the amount of solvent was increased from 30 to 60% while the crosslinkage was kept constant at 30% and the diluent used was DOT. It was observed that the porosity of resins increased as the fraction of solvent increased. However, surprisingly, the Na+ capacity did not show any appreciable change by varying the amount or nature of diluent, remaining approximately 4 meq/g. The resin remained mechanically strong despite higher porosity. The mechanical strength also did not show any significant change by varying the diluent or amount of diluent. (C) 2004 Wiley Periodicals, Inc.