THERMODYNAMICS OF MICELLIZATION OF AEROSOL OT IN BINARY-MIXTURES OF WATER, FORMAMIDE, ETHYLENE-GLYCOL, AND DIOXANE

The results of critical micelle concentration of aerosol OT in pure an d binary mixtures of water, formamide, ethylene glycol, and dioxane de termined by the methods of conductance, surface tension, spectrophotom etry, and calorimetry are presented. The cmc values by the different m ethods are in agreement with one another and have shown positive devia tions with maxima in all the binary solvent mixtures at characteristic compositions. In this behavior, mixtures containing water are distinc tly different than those without water. The water-containing mixtures have shown both negative and positive enthalpies of micellization wher eas those without water are all associated with positive enthalpy. The entropies of micellization are all positive, and they nicely compensa te the enthalpies of the process. The heat capacities of the resulting mixtures have evidenced weak interaction among the molecules of the m ixed solvents.