DYNAMICS OF WATER-CONTAINING SODIUM BIS(2-ETHYLHEXYL)SULFOSUCCINATE (AOT) REVERSE MICELLES - A HIGH-FREQUENCY DIELECTRIC STUDY

The high-frequency dielectric response of AOT reverse micelles in n-he ptane and CCl4 has been measured in the range 0.01-20 GHz as a functio n of the water-surfactant ratio (W). A relaxation phenomenon has been observed which is connected to the single particle dynamics. This diel ectric relaxation depends on surfactant hydration and is markedly affe cted by interparticle interactions. At low values of the volume fracti on phi of dispersed matter (water + AOT), interparticle interactions a re negligible and the behavior of the dielectric relaxation vs W has b een interpreted in terms of two coexisting diffusion mechanisms: the r eorientation of the whole micelle and the ''free'' diffusion of the co mpletely hydrated BOT ion pairs. As phi is increased, interparticle in teractions start to play a role and the dielectric relaxation is consi derably affected by the nature of the external oil and by the addition of small amounts of electrolyte.