Thermodynamic Analysis of Mixed Adsorbed Film and Micelle Compositions above Critical Micelle Concentration

In this paper, we proposed a thermodynamic procedure to evaluate binary surfactant mixed adsorbed film and mixed micelle compositions above critical micelle concentrations. This theory first calculates the change in the molar ratio of two surfactants in monomer and micelle states based on the phase-separation model and then imposes the chemical equilibrium between the mixed adsorbed film and mixed micelle of known composition and concentration. We applied this theory to a cationic-nonionic surfactant mixed system, and the relationship between the calculated mixed adsorbed film composition and foam film stability was discussed using the DLVO theory.