Thermodynamic and microscopic properties of AOT/Dynol-604 mixed micelles in aqueous solutions

• CMCs of mixed micelle systems of AOT/Dynol-604 were measured.
• Dilution enthalpies of monomer and micelle in aqueous solutions were determined.
• Micropolarity, sizes and aggregation numbers of the mixed micelles were measured.
• Excess thermodynamic properties of the surfactant mixtures were reported.
• Various interactions were discussed.

Thermodynamic and microscopic properties of bis(2-ethylhexyl) sodium sulfosuccinate (AOT)/ethoxylated-2,5,8,11-tetramethyl-6-dodecyne-5,8-diol (Dynol-604) mixed micelles were investigated at 298.15 K by isothermal titration calorimetry, fluorimetry, and dynamic light scattering. Critical micellar concentrations, enthalpy changes upon dilution and micellization, the polarities of the microenvironment, the sizes and aggregation numbers of the micelles, and the excess thermodynamic quantities of the mixed micelles were obtained to deepen the understanding of the synergistic effect in the mixed surfactant systems.