Antipercolation

Tingey et al. [128] reported an "antipercolation" feature of a water/dodecyldi-methylammonium bromide/supercritical propane microemulsion in the pressure range of 80-400 bar the conductance decreased by three orders of magnitude. The interconnected channels of the studied bicontinuous system were anticipated to break down into dispersed droplets. 

These experimental results can be rationalized by the DOC-cylinders model, which is the only one consistent with the presence of antipercolation thresholds in the phase diagrams, and also with the position of the maximum peak in the scattering diagram as a function of the angle obtained from SAXS experiments. This maximum is directly linked to a preferred distance... 

The method of deducing solute location from the scattering peak shift in the case of spherical reversed-micelles can be generalized to the case of connected structures (56). For instance, consider the model case of a bicontinous structure, close to the electrical antipercolation threshold. Take the polar volume fraction to be in the range 0.3 to 0.4 and the specific area to be E = 0.02 A /A, which corresponds to a 0.5 M solution of a classical surfactant. In addition, consider a chain length of 15 A and an initial surfactant packing parameter of Po = 1.25. 

It is generally believed that the increase of temperature by accelerating the droplet Brownian motion facilitates the transport of charges, which results in an increase of the conductance. This is true for ionic surfactants. However, opposite behaviors have been reported, especially with nonionic surfactants, where a temperature increase is associated with a decrease of conductivity.The word antipercolation has been used to refer to the increase of conductivity associated with a decreasing water content. 

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