Enthalpy–Entropy Compensation for Micellization and Other Hydrophobic Interactions in Aqueous Solutions

Abstract

The temperature dependence of the critical micelle concentration for 26 ionic and 48 non-ionic surfactants in aqueous solutions has been reexamined and used to calculate ΔHm0 and ΔSm0, the heats and entropies of micellization, at 25 and 50 °C. ΔHm0 and ΔSm0 values exhibit a significant correlation with compensation temperatures (Tc) of 319 and 222 °K at 25 °C for the groups of ionic and non-ionic surfactants respectively. These results are compared with Tc values which are expected to be characteristic of pairwise interactions between hydrophobic solutes.