Effect of N,N-dimethyl acetamide on the critical micelle concentration of aqueous solutions of sodium surfactants

The variations of molar conductivity of various surfactants such as sodium caprylate, sodium laurate, sodium palmitate, sodium stearate, sodium oleate, sodium dodecyl sulfate, and lithium dodecyl sulfate with concentration of the surfactants for each of the solutions consisting of mixtures of varying concentrations of N, N-dimethyl acetamide in water at constant temperature of 22.0 +/- 0.2 degrees C were studied. The critical micelle concentration (CMC) for each surfactant is measured. It is found that the CMC values in mixtures of N,N-dimethyl acetamide and water solutions of various surfactants are lower than the CMC values in water, and the driving force for micelle formation correlates with solvophobicity. The surfactant-solvent interactions that drive amphiphilic self-organization in N,N-dimethyl acetamide in water are discussed. Thermodynamic parameters were evaluated for micellar system to explain the results. (C) 2011 Elsevier B.V. All rights reserved.