Effect of amides on the micellar behavior of a cationic surfactant tetradecyltrimethylammonium bromide in aqueous solution

Electrical conductivity, surface tension and dye solubilization data on the aqueous solutions of a cationic surfactant tetradecyltrimethylammonium bromide (C(14)TABr) are reported in water and in the presence of five amides viz. urea, thiourea, acetamide, dimethylacetamide and dimethylformamide at 1.0, 2.0 and 3.0 M. The experimental results indicate that micelle formation is hindered by a rise in temperature and amides have an inhibitory effect on the formation of micelles of C(14)TABr. The degree of counter ion dissociation (beta) of the micelles also increases with increasing temperature and concentration of the amide solution. From the conductivity data (at 25, 30, 35, 40, 45 and 50degreesC), the thermodynamic parameters of micellization - standard molar Gibbs energy, enthalpy and entropy were evaluated at different concentrations of amides. The micellization process was exothermic in all cases. A linear correlation between the enthalpy-entropy compensation plots for all the systems was observed.