Development of an implicit solvent model for the interfacial configuration of colloidal nanoparticles and application to the interfacial self-assembly of truncated cubes

This study outlines the development of an implicit solvent model that reproduces the behavior of colloidal nanoparticles at a fluid-fluid interface. The center-point of this formulation is the generalized Quaternion-based Orientational Constraint (QOCO) method. The model captures 3 major energetic characteristics that define the nanoparticle configuration – position (orthogonal to the interfacial plane), orientation, and inter-nanoparticle interaction. The framework encodes physically relevant parameters that provide an intuitive means to simulate a broad spectrum of interfacial conditions. For a wide range of shapes, we are able to replicate the behavior of an isolated nanoparticle at an explicit fluid-fluid interface, both qualitatively and quantitatively. Using the family of truncated cubes as test-bed, we analyze the effect of change in the degree of truncation on the potential landscape. Furthermore, we model the self-assembly of an array of cuboctahedra to provide corroboration to the experimentally observed honeycomb and square lattices. Finally, by exploring a broader range of interfacial conditions, we identify and suggest the assembly mechanism for a set of novel superlattice configurations.