EXPERIMENTAL STUDIES ON PHASE-SEPARATION IN CRITICAL MICROEMULSION AND MICELLAR SYSTEMS

We have studied the phase separation process in two systems containing surfactant molecules, i.e. a three-component microemulsion system mad e by a Aerosol OT-water-decane surfactant and a water-Butoxyethanol (C (4)E(1)) micellar-like mixture. The analyses were performed by using t he time resolved light scattering intensity technique. All the three s tages of the process were studied. The time evolution of intensities f or the initial stage follows closely the linearized theory. Time evolu tion of the characteristic wave vector and the intensity distribution in the intermediate and late stages are in good agreement with scaling models. A comparison of the obtained data in the late stage with the findings of a recent Molecular Dynamic simulation, carried out in mixt ures containing surfactant, gives a clear indication that in the inves tigated systems the phase separation process occurs through the format ion of different structural coalesing domains. Whereas in the AOT micr oemulsion system the separation occurs through the formation of irregu lar bicontinuous-like domains, in the water-C(4)E(1) mixture the separ ation is dominated by micellar domains which depend by thermal fluctua tions.