Surface-directed spinodal decomposition versus wetting phenomena: computer simulations

Abstract

If a binary mixture, confined by hard walls that prefer one component, is quenched from the one-phase region to the two-phase region, phase separation near the wall is characterized by concentration waves with wavevectors oriented perpendicular to the walls. The dynamics of this surface-directed spinodal decomposition is investigated by numerical simulations. We consider cases with short-range and long-range forces due to the walls, with special focus upon the interplay of this structure formation with the growth of wetting layers. Attention is also paid to the change of the equilibrium phase diagram of the mixture as a result of confinement in the thin film geometry, and the consequences that one expects for the dynamical behavior of phase separation. While most of the numerical results concern systems at critical composition, some results on off-critical quenches are also presented.