Effective interaction between confined colloids: repulsion or attraction?

Abstract

Using computer simulations of the primitive model, we calculate the effective force acting onto a single macroion and onto a macroion pair in the presence of slitlike confinement between charged plates. For moderate Coulomb coupling, we find that this force is repulsive. Under strong coupling conditions, however, the sign of the force depends on the distance to the plates and on the interparticle distance. In particular, the particle-plate interaction becomes strongly attractive for small distances, which leads to colloidal crystalline layers near the plates as observed in recent experiments.