SOLUBILIZATION IN MIXED MICELLES

Solubilization capacities for decane have been determined for a variety of mixed surfactant systems. Negative deviations from additivity are observed for nonionic/ionic mixtures where there are no attractive interactions between the surfactant headgroups. "Synergistic" positive deviations from additivity are observed for anionic/cationic mixtures, where strong attractive forces between the headgroups exist. The results are interpreted in terms of curvature effects using the Israelachvili, Mitchell and Ninham v/a o l model and a model based on Laplace pressures. Data are also presented for the C12TAB/C12EO6 system which clearly shows the differences in the solubilization sites for hexanol, which solubilizes in the palisade region, and decane, which solubilizes in the micellar core. The results indicate that any future modeling will have to include surfactant-solubilizate interactions as well as surfactant-surfactant interactions. © 1990 AOCS Press.