CTS-9615649 Elias Frances Purdue University The surface tension of several aqueous systems of surfactant and surfactant/protein mixtures is examined, to find out how components of different size, surface activity, or molecular character compete for the air/water surface. New models for both equilibrium and dynamic adsorption of mixtures are developed. To test the models, several optical and spectroscopic tools are used to obtain compositional and microstructural information: external-reflection infrared spectroscopy (IR) from air/water surface monolayers; ATR-IR (total reflection) spectroscopy from monolayers (LB films) transferred on solid substrates; ellipsometry at several wavelengths; and radiotracer methods. The objectives are to develop quantitative guidelines on how the mixture composition and the molecular structures of the components can be tailored to control the dynamic surface tension behavior. Dispersions of sparingly soluble particulate surfactants and their equilibrium and dynamic adsorption are used to rationalize how foam stability and surfactant concentrations in the foamate are related to bulk composition, and to foam-based separations. The project also has a biomedical engineering focus: several specific surfactants and lipids with applications or potential applications as lung surfactant replacement drugs are examined to delineate the best conditions for achieving the very low 10 mNm nonequilibrium surface tensions (under pulsating are conditions) required for proper alveoli function.
