ISSN:
1089-7690
Quelle:
AIP Digital Archive
Thema:
Physik
,
Chemie und Pharmazie
Notizen:
Percolation in reverse microemulsion systems can be driven by various field variables, including temperature and cosurfactant concentration. We use dielectric spectroscopy and a macroscopic dipole correlation function (DCF) derived therefrom to examine mesoscale structural aspects of charge transport in a water, AOT, toluene reverse microemulsion that is driven into percolation by cosurfactant (acrylamide). A multiexponential fitting of the DCF data gives firm support to the importance of a parameter marking the onset of percolation, as distinguished from the percolation threshold. A stretched exponential fitting of the DCF data reveals microstructural and mesoscale similarities and differences between this case of cosurfactant-induced percolation and a previously examined case of temperature-induced percolation. This cosurfactant-driven system appears to exhibit a critical slowing down on approach to the percolation threshold, as does the temperature-driven case, but a much shorter relaxation time suggests the development of much less fractal structure in this cosurfactant case. The effective fractal dimensionality and number of self-similarity stages of the fractal structure are only weak functions of the reduced field variable in the case of cosurfactant-driven percolation, and contrast sharply with the temperature case. © 1999 American Institute of Physics.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1063/1.479994
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