Electrostatic interactions in concentrated colloidal dispersions

This is the authors' abstract. We don't add key points for this paper.

An explicit expression, free from adjustable parameters, is derived for the effective pair interaction between charged colloidal spheres at high concentration in a medium containing an electrolyte. This is accomplished by first considering the electrostatic interaction between two infinite charged plates placed in a stack of identical plates. These act as a reservoir defining the chemical potentials of solvent and electrolyte ions in a way that depends on the plate separation in the stack. The results for the planar case are then applied to a suspension of identical charged spheres. Also for this case the concentration defines the properties of a reservoir quantitatively affecting the particle-particle interaction. At short range this interaction can be determined using the Derjaguin approximation relating the interaction for the planar system to the inter-particle force. In the opposite limit the effective potential around the most probable separation is derived assuming pair-wise additive interactions from nearest neighbors. For very concentrated systems the Derjaguin approximation can be used. For a more dilute system an effective local potential is derived based on solutions of the Poisson-Boltzmann equation in the cell model.