UNS: Multi-scale Simulations of Branched Thread-like Micelles

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CBET - 1500377PI: Larson, RonaldSurfactants are used in many household, medical, and industrial products. Surfactant molecules in solution can spontaneously assemble into structures, which can strongly influence the properties of the liquid. This project will develop a theory to predict the properties of solutions of thread-like micelles, which are long flexible surfactant structures. The particular focus of the proposed work is to explore the role of micelle branching in the behavior of these interesting solutions. The results of the work will be incorporated into an open source software package that will be made freely available for use in the industrial formulation of surfactant solutions. Students involved in the research will have the opportunity to gain experience in industrially-related research through internships at collaborating companies. A detailed, quantitative theory will be developed to predict the linear rheology of solutions of branched threadlike micelles, including effects of reptation (or sliding) of the micelles through the entanglement network, as well as fluctuations in the "primitive path" of the micelles, micelle breakage and rejoining, formation and breakage of network junctions, and other relaxation phenomena. These phenomena will be modeled using a "Pointer Algorithm" developed by the PI that accounts for micelle relaxation phenomena, but not for micellar branching. The incorporation of branch formation will represent a major advance in understanding the dynamics and rheology of surfactant solutions. This methodology will provide accurate estimates of micelle lengths, breakage rates, and rates of formation and breakage of branch points, and the number of branches per micelle, extracted from rheology data by fits of this data to predictions of the Pointer Algorithm.