Analysis of interfacial and micellar behavior of sodium dioctyl sulphosuccinate salt (AOT) with zwitterionic surfactants in aqueous media

The interfacial and bulk properties of mixtures of the anionic surfactant (dioctyl sulphosuccinate sodium salt, AOT) with zwitterionic surfactants 3-(N,N-dimethyldodecylammonio) propane sulfonate (DPS), 3-(N,N-dimethyltetradecylammonio) propane sulfonate (TPS), 3-(N,N-dimethylhexadecylammonio) propane sulfonate (HPS) have been studied employing surface tension, fluorescence, and viscometric techniques in aqueous media at 25 °C. It is observed that these mixtures exhibit synergism and these synergistic interactions increase with the enhancement of the hydrocarbon chain of the zwitterionic surfactant. The various physicochemical properties such as critical micelle concentration (cmc), surface excess concentration (Гmax), minimum area per molecule (Amin), aggregation number (Nagg), interaction parameters (βσ, βm  ), and thermodynamic parameters such as standard Gibbs free energy of adsorption (ΔGadso), excess free energy of micellization (ΔGex), and standard Gibbs free energy of micellization (ΔGmo) have been evaluated. The negative values of ΔGmo and ΔGadso show that the micelle formation and adsorption of surfactant at the air/solution interface is energetically favorable, while a negative value of ΔGex ensures stability of the mixed micelles formed. The Regular Solution Approximation, Motomura and Rosen’s approaches have been used to explain and compare the results. The packing parameter (p) ensures the formation of vesicles or bilayers for AOT + DPS/TPS mixtures, which can potentially be used as delivery agents for industrial applications.

Surface tension technique has been used to study the interfacial and bulk behavior of the mixed systems of AOT with DPS, TPS and HPS.Figure optionsDownload high-quality image (106 K)Download as PowerPoint slideHighlights
► The negative values of interaction parameter support synergism.
► The packing parameter confirms vesicle formation for most of the mixtures.
► Surface excess and relative viscosity increases on mixing the surfactants.
► Excess free energy of micellization ensures the stability of mixed micelles.