Interfacial curvature of surface active substances

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During the current discovery grant a new surfactant characterization parameter, the characteristic curvature was introduced to describe the hydrophilic-lipophilic nature of ionic (Cc) and nonionic (Ccn) surfactants. Furthermore, these parameters were introduced into the Net-Average Curvature (NAC or NAC-HLD) equation of state for surfactant-oil-water (SOW) systems. The NAC-HLD was shown to be able to predict the curvature of microemulsion aggregates formulated with anionic, nonionic and mixtures of anionic-nonionic surfactant mixtures, a first in colloid science and technology. This grant application involves three objectives to advance the understanding and use of the NAC-HLD equation of state. The first objective involves the development of an "expert system" that based on the NAC-HLD equation can predict not only curvature and interfacial tensions, but also phase transitions, solubilization, densities, and incorporate new models to predict aggregate shape, microemulsion viscosity, and emulsion stability. The second objective seeks to find the linkage between the empirical relations built into the NAC-HLD models and molecular interactions, as defined by characteristic interaction distances that can be expressed as curvature terms. The third and final objective involves the use of the NAC-HLD model in designing SOW separation methods, with special emphasis in the study of the dynamic aspects of solubilization and phase transitions in microemulsions. The project involves the training of 3 PhD students (one for each objective) and 8-10 undergraduate summer students who would aid in the experimental components of objectives 1 and 3. The expected outcome of these studies involve a software (expert system) that can be used by formulators of cosmetics, pharmaceuticals, detergents, emulsifiers and de-emulsifiers for various industrial processes, including oil extraction operations. Furthermore, the new separation processes involved in objective 3 may open the door to the use of "green solvents" and of separation processes that do not involve evaporation (high energy input) to produce a clean oil product.