WATER IN HYDROGELS .1. A STUDY OF WATER IN POLY(N-VINYL-2-PYRROLIDONE METHYL-METHACRYLATE) COPOLYMER

NMR relaxation data for the hydrate copolymer poly(N-vinyl-2-pyrrolidone/methyl methacrylate), P-(NVP/MMA), reveal that a significant part of the water is nonfreezable or bound in the sense that it becomes mobile, much like a glass, at approximately 170 K. Consideration of T2 component intensities allows one to estimate the relative fractions of three distinguishably different types of water in P(NVP/MMA). The bound water can be resolved into a mobile component characterized by a long T2 (type A) and a component of lower mobility that combines with plasticized polymer to form an intermediate T2 (type B). This study highlights the importance of taking the plasticized polymer contribution into account in estimating bound water by the NMR technique.