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 m 2 /s. The value for a 0.5 wt % saponified starch–polyacrylonitrile graft copolymer was 1.28 (±0.26) × 10 −9 m 2 /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 m 2 /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