Phase behavior, structural effects, and volumetric and transport properties in nonaqueous microemulsions

We report here results concerning nonaqueous microemulsions containing sodi um bis(2-ethylhexyl)sulfosuccinate (AOT)+ hexane + nonaqueous polar compone nt, i.e., ethyleneglycol/2-pynolidinone/ glycerol/methanol, over a wide ran ge of volume fraction (phi) of dispersed phase at 30 degrees C. The influen ce of such nonaqueous systems on conductivity, dynamic viscosity, density, and ultrasonic velocity have been investigated. Electrical conductivity (si gma) and viscosity (eta) data show the existence of a percolation threshold . An excellent agreement between the (sigma/phi)(expt) and (sigma/phi)(calc ) calculated from the prediction of the droplet charge fluctuation model ha s been observed. The aggregation number (n), core radius (r(n)), and surfac e number density of the surfactant molecules at the interface (alpha(s)) ha ve also been computed. Droplet size in the case of the AOT + hexane + metha nol system primarily depends on the molar ratio omega, according to r(n)=0. 545 (+/- 0.021) + 0.366(+/- 0.006)omega. The phase behavior showing the rea lm of existence of microemulsion for the systems AOT + hexane + ethylenegly col/methanol has been delineated at 30 degrees C.