Structural Analysis of Microemulsions Using Small Angle Xray Scattering and Neutron Scattering for Energy Storage Systems

This thesis chapter presents a detailed investigation of the structural properties of microemulsions prepared using water, toluene, butanol, and Brij-35 surfactant. The structural evolution of the microemulsions was monitored using small-angle neutron scattering (SANS), a technique particularly well-suited for studying such systems at the nanoscale. By maintaining a constant oil mass percentage and systematically varying the water-to-surfactant mass ratio along a fixed oil-to-surfactant dilution line in the phase diagram, the study reveals key structural changes in the microemulsion. The analysis provides insights into several fundamental parameters, including domain size, correlation length, amphiphilicity factor, surfactant head group area, Critical Packing Parameter (CPP), and bending moduli. These parameters are crucial in understanding how the microemulsion structure responds to compositional changes. Specifically, the controlled variation of the water-to-surfactant ratio, while keeping the oil composition constant, uncovers a significant compositional region characterized by structural similarities. This provides valuable information on the correlation between microemulsion structure and its physical properties. Further, a comparison between the physical properties of Brij-35 microemulsions and those of Tween 20 microemulsions in analogous regions of the phase diagram offers critical insights into how the structure of the surfactant influences the resulting microemulsion architecture. These findings are expected to play a pivotal role in guiding the formulation of microemulsions for specific applications, particularly in the development of microemulsion-based electrolytes for energy storage systems. The comprehensive understanding of surfactant effects on microemulsion structure gained from this study will thus provide a foundation for advancing electrolyte design in energy storage technologies.