The transport properties near the percolation temperature threshold in the ternary water-in-oil microemulsion stabilized by ionic surfactant has been studied by measuring the self-diffusion coefficients of all the constituents of the microemulsion, and the conductivity for temperatures between 10 and 40 °C. It can be conjectured that two different transition mechanisms of the charge carriers in this temperature region may take place. These may be attributed to either the transfer of counterions from one droplet to another through water channels or hopping of surfactant ions from droplets within clusters. The results support the hypothesis that the conductivity and dielectric polarization below the percolation threshold is mainly due to the motion of counterions via water channels within the droplet clusters and not a charge-hopping mechanism at the surfactant interface. Above the percolation threshold the latter mechanism also appears, connected with migration of surfactant molecules from droplet to droplet within a percolation cluster. The first mechanism, however, still dominantes.

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Cooperative dynamics of three-component water-oil-surfactant microemulsions based on sodium bis͑2-ethylhexyl͒ sulfosuccinate surfactant were investigated near the percolation threshold. The measurements were made by means of the time domain dielectric spectroscopy method in the temperature interval 12°C-40°C, including the percolation range. The data treatment was carried out in time domain in terms of the macroscopic dipole correlation functions ͑DCFs͒ related to the structural and kinetic properties of the system. It is shown that the DCF can be described by the Kohlrausch-Williams-Watts ͑KWW͒ expression exp͓Ϫ͑t/͒ ͔ ͑where is the relaxation time and is the stretched parameter͒, reflecting the peculiarities of the dipole interactions in a self-similar medium. For a physical interpretation of the phenomenological parameters and , a generalization of the known model of the cooperative relaxation was made. The model developed was adjusted for a description of the relaxation in microemulsions that have a fractal nature in the percolation region. The results obtained testify that parameters and in the KWW function are related to the structure of the system and reflect the cooperative behavior of microemulsion droplets near the percolation threshold. It was shown also that the macroscopic law of the relaxation of the KWW type is insensitive to the microscopic details of charge transport in the system and that there is a limited temporal range for the applicability of the stretched law of relaxation in time domain. In order to extend the initial temporal interval of the applicability of the relaxation function the correlation to the KWW term was found. ͓S1063-651X͑96͒09511-6͔