Influence of methanol and dimethyl sulfoxide and temperature on the micellization of cetylpyridinium chloride

Abstract

The micellar behavior of cetylpyridinium chloride (CPC) in water and polar non-aqueous solvents has been investigated in the temperature range of 298.15–323.15K using conductivity methods. The specific conductivity versus concentration plot determines the micellization parameters using critical micelle concentration (CMC) and degree of counter-ion dissociation (α) of the micelle. It was observed that the micellization tendency of the surfactant decreases in the presence of solvents.Thermodynamic properties such as the standard free energy of micellization (∆Gmo), the standard enthalpy of micellization (∆Hmo), the standard entropy of micellization (∆Smo), the standard free energy of transfer (∆Gtranso) and the heat capacity of micellization (∆mCp°) of CPC are significantly affected by the addition of methanol and dimethyl sulfoxide (DMSO). The solvophobic parameter characterized by the Gibbs energy of transfer of hydrocarbons from gas into a given solvent can be used to account for the effect of methanol and DMSO on the formation and growth of the CPC aggregate in water.