Synthesis of strongly basic anion exchange resins based on glycidyl methacrylate-ethylene glycol dimethacrylate copolymer. Effect of amount and nature of diluent, and the degree of crosslinkage on the resins properties

Abstract

A number of hydrophilic copolymers based on glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EGDM) were synthesized using the technique of suspension polymerization. A number of diluents such as dimethylpthalate (DMT), diethylpthalate (DET), dibutylpthalate (DBT) and bis-2-ethylhexylpthalate (diocylphthalate, DOT) were used. The resulting polymers were modified into strongly basic anion exchange resins using 50% aqueous trimethylamin hydrochloride solution. In this study, the effects of amount and nature of diluents on resin properties, i. e. porosity, density, mechanical properties and capacities, were investigated. The effect of amount of crosslinking agent, i.e. the amount of EGDM, was also studied. It was found that resin become porous as the number of methylene groups in diluents increases. The pore volume changes from 0.05 to 1.35 ml/g as the diluent change from DMT to DOT. The mechanical strength of the resin decreases on increasing the number of methylene groups in the diluent. However, the chloride capacity shows no significant change. By varying the amount of crosslinking agent (from 10 to 50%) the chloride capacity changes from 3.46 to 1.2 meq/g, respectively. The effect of crosslinking on porosity was also investigated. It was found that porosity of the resin increases on increasing the amount of EGDM. This is the first time that strongly basic anion exchange resin based on GMA-co-EGDM using different and varying amounts of diluents, as well as various degrees of crosslinkage, were synthesized and characterized. The important aspect of this study is that it provides a guideline for the synthesis of a resin with specific properties by selection of a diluent and varying its ratio with respect to the monomer.