THERMAL HYDRODYNAMIC FLUCTUATIONS IN MICROEMULSIONS

Collective thermal excitations in microemulsions are studied within the hydrodynamic correlation theory. Spherical microemulsion droplets (micelles) are coated with a thin film and immersed in a fluid with different properties. The compressibility and viscosity of the bulk fluids are taken into account as well as the curvature energy and the redistribution of the surfactant concentration on the micelle surface. The method of analysis comprises a solution of the linearized dynamic (hydrodynamic and boundary) equations with random (bulk and surface) sources and application of the fluctuation-dissipation theorem. The spectral densities of correlation functions are obtained for both the hydrodynamic fluctuations in the bulk fluids and the shape fluctuations of micelles. The dynamic structure factor of the model microemulsion is calculated. © 1994 The American Physical Society.