Electrical Double-Layer Interaction between Charged Particles near Surfaces and in Confined Geometries

The proximity effect of one or two flat surfaces on the double-layer interaction between two identically charged colloidal particles immersed in an electrolyte is examined. Simple analytical formulas are presented for the interaction of (i) two particles in the vicinity of a charged flat surface and (ii) two particles confined between two parallel plates. It is found that the surface(s) can strongly influence the pairwise interaction of the particles, leading to increase, decrease, or even elimination of the electrostatic interaction, in comparison to the corresponding result in an unbounded electrolyte. Copyright 1999 Academic Press.