Studies of colloidal interactions using total internal reflection microscopy

Total internal reflection microscopy has been used to study the interactions between a single colloidal particle and a solid surface in an aqueous environment. The effects upon the interaction of various concentrations of 1:1 electrolyte were in good accord with expectation, except at distances less than 100-150 nm, where an additional attractive interaction of presently unknown origin appeared. In the presence of an electric field normal to the surface, the interactions were modified in a manner which accorded well with electro-kinetic theory, allowance being made for the hindered diffusion near a wall. Addition of adsorbing polymer (polyethylene oxide) above a threshold concentration inhibited irreversible bonding of the particle to the wall. The observed interaction of an oil-in-water emulsion droplet with the solid surface showed no effects of drop deformation. These results are discussed in the light of recent studies. (C) 1998 Elsevier Science B.V.