Effects of Addition of Amphiphilic Molecules on the Dispersion Stability of Colloidal Systems

Abstract

It is well known that amphiphilic materials can affect dispersion stability of colloidal systems. They work as a sensitizer (coagulant) to destabilize dispersion state of colloids in some situa tion, and as a protecting agent to stabilize colloids in other situations. There are a large variety of amphiphilic materials such as small-molecular surfactant and amphiphilic biopolymers, proteins or polysaccharides, and one have to give careful consideration to the effects of each amphiphile case by case. In this review article, the author focused attention to 1) the influence of small-molecular ionic surfactants to the colloidal stability of suspensions (especially, negatively charged polystyrene latex) and 2) the formation of O/W emulsions using three kinds of proteins having emulsifying ability (bovine serum albumin, β-lactoglobulin, and β-casein) and their stability. Experimental data concerning adsorption behaviors of these surfactant or protein molecules are presented, and the relation between the adsorbed amount of these molecules and dispersion stability of colloidal particles was briefly explained.