Interaction of planar double layers in the modified Gouy-Chapman approximation

Abstract

The force between two charged planar surfaces containing an electrolyte solution is calculated. The calculation is done for a 1-1 electrolyte with size-asymmetric ions using a Modified Gouy-Chapman theory. It is shown that at least part of the explanation for the sharp rise in the force between charged surfaces at small separations seen in experimental data may be related to finite-sized ion effects in the double layer. An interesting effect of size-asymmetric ions is the prediction of a force between uncharged surfaces.