MECHANISM OF TRANSPORT OF CHARGE-CARRIERS IN THE SODIUM BIS(2-ETHYLHEXYL) SULFOSUCCINATE-WATER-DECANE MICROEMULSION NEAR THE PERCOLATION TEMPERATURE THRESHOLD

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 temper atures between 10 and 40 degrees C. It can be conjectured that two dif ferent transition mechanisms of the charge carriers in this temperatur e region may take place. These may be attributed to either the transfe r 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 polarizat ion below the percolation threshold is mainly due to the motion of cou nterions via water channels within the droplet clusters and not a char ge-hopping mechanism at the surfactant interface. Above the percolatio n threshold the latter mechanism also appears, connected with migratio n of surfactant molecules from droplet to droplet within a percolation cluster. The first mechanism, however, still dominantes.