Physicochemical Characterization of Anionic and Cationic Microemulsions: Water Solubilization, Particle Size Distribution, Surface Tension, and Structural Parameters

The composition, oil type, and thermodynamic parameters influence the water solubilization capacity, particle size distribution, surface tension, and also the structural parameters of microemulsion systems. In the present study sodium lauryl sulfate (SLS) and hexadecyltrimethylarrunonium bromide (HTAB) have been used as surfactants and 3-methyl-1-butanol as cosurfactant to prepare microemulsions. Four n-alkanes (hexane, heptane, decane, and dodecane) were chosen as oil phases. Water solubilization capacities of anionic (SLS) and cationic (HTAB) microemulsions were investigated in both the presence and the absence of NaCl salt. A detailed study of particle size analysis for both the surfactants with different composition has been made from laser light scattering measurement. Surface tensions of microemulsions and surfactant solutions were also measured for investigation of their surface activities. Surface tensions have been reduced remarkably in the case of microemulsion systems compared to simple aqueous solutions of surfactants. Different structural parameters like water droplet and effective microemulsion droplet size including interface, aggregation numbers of surfactant, and cosurfactant have been determined assuming monodispersity of the droplets from dilution experiment. The effects of temperature on the above parameters have also been studied.