Kremer, F., Lagaly, G., Texter, J., Antalek, B., García, E., and Williams, A. J.
This volume focuses on examining physical phenomena that occur in colloidal systems such as micellar solutions, microemulsions, emulsions, dispersions, slurries, etc. It principally concentrates on liquid/air, liquid/liquid, and liquid/solid interfaces. The work summarizes our current understanding of interfacial structure at the molecular level in these systems, and the relation of this structure to chemical and physico-chemical phenomena. Faradaic electron transfer in reverse microemulsions of water, AOT, and toluene is strongly influenced by cosurfactants such as primary amides. Cosurfactant concentration, as a field variable, drives redox electron transfer processes from a low-flux to a high-flux state. Thresholds in this electron-transport phenomenon correlate with percolation thresholds in electrical conductivity in the same microemulsions and are inversely proportional to the interfacial activity of the cosurfactants. The critical exponents derived from the scaling analyses of low-frequency conductivity and dielectric spectra suggest that this percolation is close to static percolation limits, implying that percolative transport is along the extended fractal clusters of swollen micellar droplets. 1H and 13C NMR spectra show that surfactant packing transitions are also driven by changes in cosurfactant concentration. These packing transitions provide a physical basis for these electron transfer and conductivity percolation phenomena. Self-diffusion measurements derived from NMR pulsed gradient spin echo experiments show that water proton diffusion increases at the onset of electrical conductivity percolation and is transported along extended clusters. A dynamic partitioning model provides a direct measure of the volume fraction of these percolating clusters and an order parameter for quantifying water-in-oil droplet to percolating cluster ] microstructural transitions. [ABSTRACT FROM AUTHOR]