Diffusion Coefficients of Water in Biobased Hydrogel Polymer Matrices by Nuclear Magnetic Resonance Imaging

The diffusion coefficients of water in biobased hydrogels were measured with a simple NMR method. This method tracked the migration of deuterium oxide through imaging data that was fit to a diffusion equation. The results show that a 5 wt % soybean-oil-based hydrogel gave an aqueous diffusion of 1.37 (±0.21) × 10−9 m2/s. The value for a 0.5 wt % saponified starch–polyacrylonitrile graft copolymer was 1.28 (±0.26) × 10−9 m2/s, which remained about the same at increased polymer content in the hydrogel. For comparison, a commercially available acrylic polymer was evaluated with the same methodology and was found to have a diffusion coefficient of 7.6 (±1.3) × 10−10 m2/s, about half that of the biobased products studied here. These parameters are of significant interest in the development of controlled release applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012