(675a) Synergistic Effects in the Adsorption of Surfactant Mixtures Studied Via Molecular Simulations

While previous works have largely focused on understanding the adsorption behavior in single surfactant systems, in practical applications, mixtures of surfactants or those of surfactants and hydrocarbon molecules are often employed as they are reported to significantly improve the properties of the adsorbed surfactant layers. Experiments have revealed that adsorbed surfactant layers can undergo morphological transitions with the addition of another surfactant type. At present, there is little understanding of the origins of this synergistic behavior of surfactant mixtures. In this work, we will discuss our recent simulation results wherein we demonstrate that co-adsorption of hydrocarbon molecules in adsorbed surfactant layers result in the transition of the adsorbed morphology from cylindrical to a planar self-assembled monolayer. In addition, we will discuss the co-adsorption behavior of surfactants of different tail lengths. Drawing parallels to solution thermodynamics, we will discuss how the adsorption behavior of surfactant mixtures can be understood in terms of positive and negative deviations from the behavior of ideal mixtures.