INTERFACIAL AND CAPILLARY PROPERTIES OF A MICELLAR SOLUTION MODEL

A prominent feature of the phase behavior of aqueous solutions of noni onic amphiphiles is a phase separation into dilute and concentrated mi cellar liquids above a lower critical solution temperature T-c. Experi ment has revealed a strong asymmetry of the coexistence curve, a high sensitivity of the (effective) critical indexes on deviations of the c ritical composition, and an unusual excess adsorption at the liquid-li quid interface as indicated by ellipsometric measurements. Here, we re view and extend the study of a micellar solution model designed to des cribe amphiphiles in polar solvents and, as we illustrate, it reproduc es the properties mentioned above. The model allows for elimination of the degrees of freedom within the aggregates, and this leads to an eq uivalence with the ordinary Ising model but with temperature and conce ntration-dependent field and coupling. The latter is identified with t he effective intermicellar interaction.