EFFECT OF COMPOSITION ON PROPERTIES OF COPOLYMERIC N-VINYL-2-PYRROLIDONE METHYL-METHACRYLATE HYDROGELS AND ORGANOGELS

Gamma irradiation has been used to copolymerize N-vinyl-2-pyrrolidone with methyl methacrylate to high conversion in both the presence and absence of ethyleneglycol dimethacrylate. The resultant solid xerogels were swollen to equilibrium in water and in dioxane to yield hydrogels and organogels respectively. The gels were characterized by uniaxial compression measurements and by determination of sol fraction, equilibrium solvent content, dimensions, effective crosslink density (ve) and polymer-solvent interaction parameter (χ). The Q-e scheme was used to compute instantaneous compositions of the terpolymer components at all stages of conversion, and compositional drift served to interpret the heterogeneous crosslinking at some compositions. No measurable effect of temperature on ve could be discerned. When the temperature was increased from 278 to 343 K, the hydrogels underwent deswelling with an increase in χ, whereas, over a similar increase in temperature, the opposite behavi was exhibited by the organogels. © 1990.