Entropically driven ordering in a binary colloidal suspension near a planar wall

Abstract
The local ordering of a binary hard-sphere mixture with a size ratio 1:10 near a planar wall is investigated by means of integral equation theory. We find that when the bulk volume fraction of the smaller particles is greater than 15%, the larger particles (at a bulk volume fraction of 1% and higher) become highly localized on the wall surface, forming a quasi-two-dimensional surface-localized monolayer. Our results are discussed and compared against computer simulation data with an effective one-component Hamiltonian that is based on sphere-sphere and sphere-wall depletion potentials.