Micellar Properties and Related Thermodynamic Parameters of the 14-6-14, 2Br- Gemini Surfactant in Water plus Organic Solvent Mixed Media

Micellar parameters such as critical micelle concentration (cmc), degree of counterion dissociation (alpha), and aggregation number (N-agg) of the cationic gemini surfactant hexamethylene-1,6-bis(tetradecyldimethylammonium bromide) (14-6-14, 2Br(-)) have been determined in aqueous binary mixtures of dioxane (DO), dimethylformamide (DMF), and ethylene glycol (EG) by employing conductivity and fluorescence methods. An increase in the cmc and alpha values and a decrease in the N-agg were observed when volume fractions (phi) of the studied organic solvents were varied (0 to 0.80 for conductivity and 0 to 0.50 for fluorescence studies) at 303.15 K. The temperature dependence of the cmc values provided information about various thermodynamic parameters and its effect on the selected compositions (phi = 0, 0.10, 0.20, 0.30, and 0.50) of the mixed media on varying the nature of the medium. The Gibbs energy of micellization (Delta G(m)(0)) increased with the increase in the phi of the studied organic solvents. It was also observed that the increase in the cmc with the rise in temperature was more in the media containing a higher (phi) of the organic solvents.