Depletion forces near curved surfaces

Abstract

Based on density functional theory the influence of curvature on the depletion potential of a single big hard sphere immersed in a fluid of small hard spheres with packing fraction η_s either inside or outside of a hard spherical cavity of radius R_c is calculated. The relevant features of this potential are analyzed as function of η_s and R_c. There is a very slow convergence towards the flat wall limit R_c \to \infty. Our results allow us to discuss the strength of depletion forces acting near membranes both in normal and lateral directions and to make contact with recent experimental results.