Controlling the wetting properties of the Asakura–Oosawa model and applications to spherical confinement

Abstract

We demonstrate for the Asakura–Oosawa model and an extension of this model that uses continuous rather than hard potentials, how wetting properties at walls can be easily controlled. By increasing the interaction range of the repulsive wall potential acting on the colloids (while keeping the polymer–wall interactions constant) polymers begin to substitute colloids at walls and the system can be driven from complete wetting of colloids via partial wetting to complete wetting of polymers. As an application, we discuss the morphology and wetting behavior of colloid–polymer mixtures in spherical confinement. We apply the recently developed ‘ensemble switch method’ where the Hamiltonian is extended to a combination of a system with walls and of a system without walls to calculate the surface excess free energies of colloid-rich and polymer-rich phases. The contact angle then is inferred from Young’s equation.