Effect of Substrate Wetting on the Morphology and Dynamics of Phase Separating Multi-Component Mixtures

We numerically study the structural evolution due to demixing of multi-component fluids in thin films on a substrate. More specifically, we explore the surface-directed spinodal decomposition of multi-component mixtures by means of Free Energy Lattice Boltzmann simulations in order to have explicit control over the free energy landscape and the equation of state of the system. We investigate the effect of composition, film thickness and substrate wetting on the phase morphology and the mechanism of growth in the vicinity of the substrate. We find that in binary mixtures the phase morphology and averaged size of the structural domains in the vicinity of the substrate varies greatly due to preferential wetting of the substrate in both the parallel and perpendicular directions. We also discuss how the model can be extended to include an arbitrary number of fluid components.