Phase transitions from catanionic salt to mixed cationic/anionic vesicles

Phase transition from crystalline catanionic salt to mixed liquid crystalline phase was investigated by polarizing microscopy, light scattering, and IR and X-ray analyses. The experiments were carried out at 298 K. The excess of one of the surfactants in the catanionic lamellar structure leads through a series of equilibria to disruption of the planar bilayer and formation of the closed bilayer vesicle. The composition of mixed cationic/anionic vesicles depends on the molar ratio between cationic and anionic surfactants. The physical forces driving from planar to curved lamellar phase transitions are mostly of electrostatic origin. (C) 1998 Academic Press.