How to study microemulsions.

The application of various experimental techniques for studying the properties of ternary mixtures H 2 O-oil-nonionic amphiphile is demonstrated. Based on detailed knowledge of the phase behavior, in particular, the positions and extensions of the three-phase bodies, the origin of the ultralow interfacial tensions and strong opalescence of the solutions is elucidated. Within the three-phase body one finds a maximum of the velocity of phase separation of the three phases that is correlated to a minimum of the viscosity and a jump of the electric conductivity. The properties of the homogeneous microemulsions are measured along a path through the phase prism at constant amphiphile concentration but varying oil/water ratio. The dynamics of the microstructure is studied by viscosity, dynamic light scattering, and electric field and pressure jump relaxation, as well as by ultrasonic absorption. The characteristic dimensions of the structure are determined by SANS and SAXS, NMR self-diffusion, electric conductivity, and freeze fracture electron microscopy.