Micellar properties of long-chain alkyldimethylbenzylammonium chlorides in aqueous solutions

The temperature dependence of critical micelle concentration (cmc), micellar degree of ionization, β, and standard free energy of micellization, ΔGmo, of tetradecyl- and hexadecyldimethylbenzylammonium chlorides in aqueous solutions has been determined from conductivity data collected in the temperature range of 10–35 °C at 5 °C intervals. The occurrence of a second break on the specific conductivity against molality plots at about three times the cmc has been confirmed. From density measurements carried out at 15, 25 and 35 °C, the change of the apparent molar volume upon micellization of the surfactants was estimated. Density data for the tetradecyl homologue suggest the existence of an additional transition of the micelles at molalities about 15 times the cmc.