Interfacial Transport Processes at Oil-Surfactant-Water Interfaces

该项目涉及许多工业分离和提纯操作中的一个非常重要的主题，即通过分离两个宏观流体相的表面活性剂界面输送材料。在胶体水平上，了解微乳液体系中受表面活性剂层界面结构影响的动态过程可以更好地从机理上描述各种现象，例如相变、乳状液稳定性、细胞和膜模拟介质中的传输，以及反胶束体系中的生物催化。为了更好地了解影响这些和其他界面传输过程的因素，PIS计划(I)研究可压缩和不可压缩表面活性剂层在阻止溶质在分离两个体相的界面，(2)研究在这种界面上反胶束的形成和聚合的动力学，以及(3)实验研究探针分子的缔合率与其通过油包水微乳液中高度弯曲的表面活性剂界面的传输，(4)建立溶质分子与表面活性剂界面相互作用的理论模型，以及界面处胶束的形成和破坏速率。微乳液体系的热松弛行为和结构松弛行为也将被讨论。为此，私人投资促进局将采用两项相辅相成的实验技术。设计了一种独特的扩散池，使转移溶质的浓度在非常接近界面的地方发生阶跃变化，而不会对界面本身造成任何干扰。碘激光温度跃变(ILTJ)方法是一种松弛技术，将被用来识别和量化微乳液体系的界面扩散时间尺度特征。

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.