The self-diffusion constant of water droplets in a three-component, oil external microemulsion containing n-decane, water, and an anionic surfactant, sodium di-2-ethylhexylsulfosuccinate (AOT1) was measured by forced Rayleigh scattering. The droplet radius was kept fixed by holding the weight ratio of surfactant to water fixed at 3:5 and the diffusion constant was measured as a function of the minor component (water + AOT) volume fraction. The diffusion constant was observed to decrease about a factor of 3 from 10-16% volume fraction of water + AOT. From 16 to 60% the diffusion constant was independent of the volume fraction of water + AOT. These results, together with previous neutron scattering measurements on this system, suggest that a bicontinuous phase is not formed. A possible explanation involving dynamically percolating clusters of water droplets is discussed.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Surfaces, Coatings and Films
- Colloid and Surface Chemistry