Prediction and Detection of Submolecularly-Ordered Fluid Phases

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ABSTRACT Proposal Number: 9313714 P.I.: Marc D. Donohue Institution: The Johns Hopkins University The behavior of complex fluids of interest because of the intriguing range of phenomena they exhibit and because of the variety of industrial processes that can take advantage of this behavior. The research proposed here will advance our knowledge of submolecular environments within a microstructured fluid. Additionally, experiments will be carried out to probe these submolecular environments. Over the past twenty years, significant advances in the thermodynamics of fluid phases have occurred; despite these improvements, most theoretical and predictive treatments of micellar solutions, liquid crystals, and microemulsions depend strongly on specific physical models of the microscopic ordering. The proposed research will employ a new technique (kuespert and Donohue, 1993a) to modify advanced equations-of-state for use with complex fluids to predict microphase equilibria such as those observed in micellar solutions and in computer simulations. An experimental program to qualitatively and quantitatively study microphase equilibria also will be conducted, focusing on nonintrusive spectrometric investigations. The polarity and polarizability of microscopically-ordered fluid phases will be examined using Fourier transform infrared spectrometry. Separation of a nonordered bulk fluid into two or more ordered microphases will be studied using that salvatochromic shifts observed in various IR spectral bands. Quantification of the polarity and polarizability of such microphases will allow interference of their compositions. The compositions thus determined then will be compared with those predicted by theory. As a cross-check on the FTIR methods, nuclear magnetic resonance measurements of solvent shifts and lanthanide shift reagent effects will be used to estimate the phase splits between microphases.