Interactions Among Surfactants

Abstract

Indications of interactions among surfactants obtained initially with insoluble long chain monolayers penetrated by soluble surfactant species are reviewed. Subsequent thermodynamic treatments of such interactions as departures from an ideal behaviour al interfaces has led to quantitative assessments. Three distinct contributions are recognized: those due to the reactivity between each individual surfactant and the solvent, and the specific interaction between the surfactants themselves. Even in the absence of a specific interaction between the two surfactants, a non-ideal behaviour at interfaces due to the surfactant/substrate contribution may have a considerable effect on surface elasticity and viscosity, influencing in turn other properties of systems whenever mixed surfactants are employed, i.e., foaming, flotation, emulsification, detergency, etc. The role of non-ionic frother molecules in neutralizing residual surface charges during particle-bubble attachment in flotation is emphasized.