Influence of organic solvents, head-groups and temperature on the micellization behavior of some cationic surfactants

Abstract

The effect of organic solvents, viz., dioxane, dimethylformamide and ethylene glycol on the micellization behavior of cationic surfactants, i.e., tetradecyltrimethyl ammonium bromide (TTAB), tetradecyldimethylbenzyl ammonium chloride (C14BCl) and their dimeric homologue, dimethylene-1,2-bis(tetradecyldimethyl ammonium bromide) (14-2-14) is studied in aqueous solutions using conductometric and viscometric techniques at different temperatures (288.15–318.15 K). It is observed that the critical micelle concentration and degree of counterion dissociation values increase with the increase in volume percentage and the temperature. Studies on the the temperature dependence of the CMC values show that the standard Gibbs free energy of micellization values increase with the concentration of organic solvents and temperature whereas the opposite trend is observed for enthalpy. The randomness of the system decreases in presence of solvents. The relative viscosity of the surfactants was found to be more in presence of ethylene glycol among the studied systems.
The effect of temperature on relative viscosity for these systems has also been discussed.