Surfactant molecules have an ever-prevalent role in our daily lives: surfactants biologically compose cell membranes, lipids, and some natural oils; they are used commercially to act as soaps, detergents, food preservatives, emulsifiers, and dispersants. The focus of this study is to model sodium dodecanoate surfactant molecules at an interface of carbon tetrachloride and water using classical molecular dynamics (MD). MD simulations allow for a structural examination of the evolution of a surfactant containing system on the nanoscale. Specifically, we simulated 25ns trajectories that can be visualized or analyzed as raw data. Radial pair distribution analysis (RPD) has been performed to track the distance between cations and atoms of the sodium dodecanoate headgroup throughout simulations. Using Python analysis scripts, we generate files that produce the density of each component as a function of distance from the interface averaged over a simulation. Integrated atomic densities as a function of distance from the interface show strong correlations between divalent cations and dodecanoate headgroups within the interfacial region. Past simulations have shown that the introduction of divalent metal cations, calcium and magnesium, at the system interface increases the interfacial width. We describe the effects of interfacial properties with the concentration of divalent cations at the interface.

Molecular modeling of amphipathic molecules at an organic/water interface in the presence of divalent cations

255th National Meeting (2018)

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