PHASE-EQUILIBRIA IN AQUEOUS LOW-MOLECULAR CATANIONIC SURFACTANT SYSTEMS

Phase equilibria in systems alkanoic acid-alkylamine-water have been determined at 298.2 K. In the system hexanoic acid (A) - hexylamine (B) only one isotropic solution phase is formed. This solution phase is in equilibrium with almost pure water. The strong A1B1 complex shows catanionic surfactant properties as concluded from phase equilibria studies in the system A1B1-heptane-water. This system behaves like ordinary microemulsions. The dominant feature of the phase diagram with ethanoic acid-dodecylamine is the large D phase. In addition there exist a large solution phase, a hexagonal phase and a small cubic I phase.