Industry/University Cooperative Research Project: Scat- tering and Spectroscopic Investigation of Non-Ideal and Colloidal Solutions

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Research Summary: In this project, molecular association in non-ideal solutions through hydrogen bonding, condensation and hydrophobic effect at the molecular level are being examined using scattering and spectroscopic techniques. Specifically, the PI will investigate: 1) Diffusion and association in solutions of alcohols and carboxylic acids; 2) Sol formation by the hydrolysis of organo-silicon esters; 3) Component activities for oil-in-water and water-in-oil microemulsions; and 4) Stability and formation mechanisms of Silicone oil/nonionic surfactant/water microemulsions. This research group was one of the very first to use the tools of light scattering and vibrational spectroscopy in investigating non-ideal solutions at the molecular scale. They combine light-scattering, which is sensitive to aggregate size, with vibrational spectroscopy (IR-Raman) sensitive to the changes at the functional group (O-H, C-H etc.) level, to find out what molecular processes and reactions are responsible for the usual macroscopic behavior of non-ideal solutions. Technical Impact: The impact of this research will be at several levels: 1) The research on association through hydrogen bonding is desperately needed in developing and refining predictive models of diffusion and thermodynamic activity in non-ideal solutions. These data are used in designing common separation processes such as liquid-liquid extraction and distillation, as well as gas purification; 2) Development of new processes to form narrow distribution silica sols in the 100 A size range from organic esters of silicon will be very useful for producing regulated secondary size standards for electron microscopy and light scattering instrument makers. A second and equally useful application will be in optical thin film coatings for high power laser optics. Finally, what is learned here is directly transferable to production of high purity, exotic ceramic powders; 3) Developing new methods of silicon oil microemulsion formation, and understanding the molecular parameters affecting their stability will impact the cost and shelf life of this new class of microemulsions. Silicone oil microemulsions have the potential to be used extensively as textile softeners as well as in cosmetic products.