Electrical double-layer interaction between charged particles near surfaces and in confined geometries

The proximity effect of one or two hat surfaces on the double-layer interac tion between two identically charged colloidal particles immersed in an ele ctrolyte is examined. Simple analytical formulas are presented for the inte raction 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 t he surface(s) can strongly influence the pairwise interaction of the partic les, leading to increase, decrease, or even elimination of the electrostati c interaction, in comparison to the corresponding result in an unbounded el ectrolyte. (C) 1999 Academic Press.