Electro-optical and dielectric properties of oil continuous aerosol ot/water/isooctane micro-emulsions

A water in oil microemulsion is a thermodynamically stable, isotropic, transparent liquid dispersion of small spherical water droplets, surrounded by a layer of surfactant molecules, in a continuous oil phase [1]. In an electric field the droplets become spheroidal. Experimentally one finds for low volume fractions a negative Kerr effect for small droplets which becomes positive for larger radii [2]. We extended these measurements. Comparison with a formula for the Kerr constant which we derive shows good agreement. For larger volume fractions the droplets cluster. This follows rather convincingly if we compare our experimental values for the dielectric permittivity with the theoretical expression.