Microemulsions Formed by a Catanionic Surfactant or by an Ionic Surfactant with an Organic Counterion

Abstract

Abstract The phase diagrams at 298.2 K for the systems heptylammonium heptanoate-heptane-water, butylammonium decanoate-butanol-decane-water and butylammonium decanoate-butanol-decane-sodium chloride (aq) have been determined. A large three-phase region and an extensive microemulsion phase were obtained for the heptylammonium heptanoate system. Addition of both cosurfactant and electrolyte brings about a separation into three phases in the butylammonium decanoate-water system. All three-phase systems were characterized by low inter-facial tensions. Sound velocity, conductivity, and viscosity measurements were used successfully for qualitative studies of microstructural transitions in the isotropic microemulsion phase.