Molecular Dynamics Simulations of Surfactant Functionalized Nanoparticles in the Vicinity of an Oil/Water Interface

Abstract

The localization of nanoparticles (NPs) at fluid/fluid interfaces has emerged as an effective self-assembly method. To understand the fundamentals of this localization mechanism, it is necessary to quantify the physical behavior of NPs in the vicinity of a fluid interface. Conventional theories treat the NP as a rigid object whose equilibrium position is dictated by the balance of its surface tensions with the two fluids. However, most NPs are functionalized with “soft” organic surface layers which play a large role in determining the shape of the NP. Through molecular dynamics simulations, we show that the functionalizing layer also greatly alters the interfacial behavior of the NP beyond the scope of common theory. Furthermore, we characterize the effect of the surface density of functionalizing molecules on the NP deformability. Our results have implications on the experimental interpretation of NP contact angles and may be useful for future theory development.