The project deals with a topic of great importance in many industrial separation and purification operations, i.e., the transport of materials across surfactant-laden interfaces separating two macroscopic fluid phases. At the colloidal level, an understanding of the dynamic processes in microemulsions systems as affected by the interfacial structure of the surfactant layer can lead to better mechanistic descriptions of such diverse phenomena as e.g., phase transitions, emulsion stability, transport in cells and membrane mimetic media, and biocatalysis in reversed micellar systems. To better understand the factors influencing these and other interfacial transport processes, the PIs plan to (i) investigate the role of compressible and incompressible surfactant layers in retarding the transport of solutes across interfaces separating two bulk phase, (ii) examine the kinetics of formation and coalescence of reversed micelles at such interfaces, and (iii) study experimentally the rate of association of probe molecules with their transport through, highly curved surfactant interfaces in water-in-oil microemulsion, (iv) develop a theoretical model for the interaction of solute molecules with the surfactant interface, and of the formation and destruction rates of micelles at the interface. The thermal and structural relaxation behavior of microemulsion systems will also be addressed. To these ends, the PIs will employ two complementary experimental techniques. A unique diffusion cell has been designed which enables the introduction of a step change in concentration of the transferring solute very close to the interface without causing any disturbance of the interface itself. The Iodine Laser Temperature Jump (ILTJ) method, a relaxation technique, will be used to identify and quantify the interfacial diffusion time scales characteristic of the microemulsion systems.
