The immiscibility of two liquids causes them to separate into distinct phases and allows for the formation of emulsions. In an emulsion, roughly spherical droplets of one of the liquids (known as the dispersed phase) are immersed in the other liquid (known as the continuous phase). The unfavorable energy of interaction between the two phases is characterized by the interfacial tension. Despite the importance of this interfacial geometry, no experimental methods exist for directly determining the interfacial tension of spherical liquid/liquid interfaces and current, indirect methods for approximating it suffer from significant shortcomings. Here, we present a new method for computing the interfacial tension of spherical liquid/liquid interfaces using Molecular Dynamics simulations. A continuum spherical solid is embedded in the spherical liquid phase and its total energy of interaction with the two immiscible liquid phases is reported. Then, a reference simulation is performed in which only the solid and one of the liquid phases are present. The interaction energy in the reference system is used to cancel the effect of the solid in the prior simulation, allowing us to extract the liquid/liquid interfacial tension. Thus far, this method shows good agreement with the virial approach in spherical polar coordinates for Lennard-Jones systems. In addition, the interfacial tensions for Lennard-Jones droplets with large radii (low curvature) were found to approach the planar interface geometry value. In the future, this method will be extended to realistic systems (such as oil and water) to determine to what extent it agrees with current interfacial tension data.

New method for determining the interfacial tension of spherical liquid/liquid interfaces using molecular dynamics simulations

251st National Meeting (2016)

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