Molecular Dynamics Simulations of Spinodal Decomposition in Films of Binary Mixtures

A molecular dynamics investigation of spinodal decomposition in films of a binary mixture demonstrates that the phenomenon “Surface-directed spinodal decomposition,” first obtained experimentally by Jones et al. [Phys. Rev. Lett. 66, 1326 (1991)], is caused not by a decomposition directed from the surface and driven by a preferential attraction toward the surface of one of the components but by the symmetry break. The main effect of this symmetry break is a decomposition into a laminar sandwich structure of separated fluid phases for film of a thickness bigger than a certain critical thickness. The domain growth exponent in the vertical direction is ≈1/3 and the growth in horizontal is ≈1/2, which corresponds to two-dimensional viscous growth.