Structural study of one-phase microemulsions

Several microemulsion microstructures were identified in the one-phase region of the sodium dodecyl sulfate/1-butanol/ toluene/2.5 wt % NaCl brine system by quasielastic light scattering, conductivity, viscosity, and steady-state fluorescence-probe measurements. At high ratios of water to oil, microemulsions are aqueous solutions of oil-swollen micelles; at low ratios of water to oil, microemulsions are oleic solutions of water-swollen inverted micelles; near the three-phase region, where the microemulsion takes up substantial amounts of both water and oil, the structure is a bicontinuous interpenetrating network of water and oil domains separated by surfactant layers. There is also a large excluded region for droplets where small hydrated surfactant aggregates solvated with alcohol molecules are dispersed in an oleic medium, and a small region, near the 2-phase boundary, where the structure is unknown.