Interfacial and Thermodynamic Properties of SDBS−C12E10 Mixed Micelles in Aqueous Media: Effect of Additives

The interfacial and thermodynamic properties of SDBS/C 12 E 10 mixed system in aqueous solution in the presence of additives, i.e., poly(ethylene glycol) 400, sucrose, and urea have been investigated. The critical micelle concentrations (cmc) were determined by both surface tension and conductivity measurements. The maximum surface excess (Γ max ) and minimum area per molecule ( A min ) were determined from surface tension data. The thermodynamic parameters of micellization and adsorption were computed and discussed. The enthalpy−entropy compensation effect was observed in all the cosolvent systems. The partition coefficient of these hydrophilic additives between the micelle and the solvent was found to be zero. The transfer quantities, which are sensitive to the solvent structure, were also computed. The interaction parameters between the surfactant molecules both in the presence and absence of additives were evaluated by Rubingh's approach. Micellar aggregation number ( N agg ) for the mixed system in the presence and absence of additives were determined by fluorescence measurements. 1 H NMR was also used to study the behavior of surfactants in mixed micelles.