COLL 390 |
| Stephanie R. Dungan, Nathan W. Lloyd, Sonia Ouni, and Ronald J. Phillips. Department of Chemical Engineering and Materials Science, University of California, Davis, Department of Food Science and Technology, One Shields Ave., Davis, CA 95616 |
| The diffusion of colloidal solutes in polymeric hydrogels plays an important role in controlled release, bioseparations, and in food and physiological systems. We have seen that hydrodynamic and steric interactions between nonionic solutes and gel fibers not only reduce diffusion at infinitely dilute solute concentrations, but magnify the dependence of the diffusion coefficient on finite concentrations. Our current work compares the diffusion of uncharged colloids with that of charged sodium dodecyl sulfate (SDS) micelles. Solute-solute interactions are much stronger in these charged systems, and this leads to an even greater effect of the gel on solute diffusion at finite concentrations. At the same time, we show that SDS self-assembly is affected by the agarose gel, and this causes a more complex dependence on gel concentration than expected for a simple charged colloidal sphere. Thus, our measurements demonstrate the influence that even a dilute, nonionic gel system has on intermolecular, colloidal, and hydrodynamic interactions during diffusion. |
|
Symposium in Memory of Arthur W. Adamson
8:30 AM-12:10 PM, Wednesday, March 31, 2004 Marriott -- Orange County 4, Oral
Division of Colloid and Surface Chemistry |