CALORIMETRIC STUDY OF THE MICELLIZATION OF N-BUTOXYETHANOL IN WATER

This paper reports on critical micelle concentrations and enthalpies of micellization of n-butoxyethanol in water at three different temperatures (5, 25, and 45 °C) as determined by means of a sensitive microcalorimeter. The experimental enthalpies are compared with those calculated from the temperature dependence of the critical micelle concentration by using the phase separation model of micelle formation. Enthalpies and entropies of micelle formation are both positive and decrease as the temperature is raised indicating the hydrophobic effect in the formation of n-butoxyethanol microaggregates. These calorimetric results provide no indications of intermicellar interactions, while indicating a monomer−monomer repulsive interaction in the premicellar region.