Submitted to: Journal of Applied Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2012
Publication Date: 6/26/2012
Citation: Doll, K.M., Vermillion, K., Fanta, G.F., Liu, Z. 2012. Diffusion coefficients of water in biobased hydrogel polymer matrices by NMR imaging. Journal of Applied Polymer Science. 125:E580-E585.
Interpretive Summary: Using modern spectroscopic methods, we have determined the diffusion coefficient of water in a series of biobased gels. Gels such as these are a key material in the controlled delivery of substances for applications such as drug delivery, flavor encapsulation and cosmetics. The use of naturally based materials in these areas is a natural fit, where previous work has shown the development of high quality gel materials. Fundamental parameters, such as diffusion coefficients, are necessary in order to determine the path for further development. They are also needed by formulators who will try to use these materials in their own sophisticated applications. This research will benefit those formulators and their companies who are looking for a way to improve their delivery products as well as the producers of biobased materials.
Technical Abstract: The diffusion coefficient of water in biobased hydrogels were measured utilizing a simple NMR method. This method tracks the migration of deuterium oxide through imaging data that is fit to a diffusion equation. The results show that a 5 wt% soybean oil based hydrogel gives aqueous diffusion of 1.37 (± 0.21) x 10-9 m2s-1. The value for a 0.5 wt% starch-polyacrylonitrile graft copolymer is 1.28 (± 0.26) x 10-9 m2s-1, which increased slightly with increased polymer content in the hydrogel. For comparison, a polyacrylic material was evaluated using the same methodology and found to have a diffusion coefficient of 7.6 (± 1.3) x 10-10 m2s-1, about half that of the biobased products studied here. These parameters are of significant interest in the development of controlled release applications.