Water sorption of interpenetrating polymer network hydrogels composed of poly(ethylene oxide) and poly(methyl methacrylate)

Anomalous water sorption behavior has been observed in interpenetrating polymer network (lPN) hydrogels composed of poly (ethylene oxide) and poly (methyl methacrylate). The water sorption of IPN hydrogels was investigated gravimetrically by dynamic vapor sorption at a relative humidity of 95%, and the collective diffusion coefficients determined at 25, 35 and 45degreesC. With increasing temperature the vapor sorption behavior, was affected more by the density of the water vapor than by the hydrophilic properties of the IPN hydrogels. The apparent activation energy was independent on the composition of the IPN hydrogels, with a value of 1.31similar to1.90 kJ mol(-1). However, the equilibrium water content was dependent on the temperature, decreasing as the temperature increased. The IPN hydrogels exhibited a relatively high equilibrium water contents, in the range 13similar to68%.