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 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.