The effect of geometrical confinement on the interaction between charged colloidal suspensions

TL;DR

This study uses computer simulations to explore how geometrical confinement influences the interactions between charged colloidal particles, revealing conditions that lead to attraction or repulsion near confining walls.

Contribution

It provides new insights into the effects of slit-like confinement on colloidal interactions, highlighting the role of Coulomb coupling strength and particle-wall distance.

Findings

Repulsive forces at moderate Coulomb coupling.

Attractive forces near plates under strong coupling.

Potential explanation for colloidal crystalline layers.

Abstract

The effective interaction between charged colloidal particles confined between two planar like-charged walls is investigated using computer simulations of the primitive model describing asymmetric electrolytes. In detail, we calculate the effective force acting onto a single macroion and onto a macroion pair in the presence of slit-like confinement. 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 may explain the occurrence of colloidal crystalline layers near the plates observed in recent experiments.