Thin Liquid Films - Structure and Stability

这项研究的目的是从实验和理论上检验使用表面活性剂制备的亚微米薄膜中的多层微结构或分层现象，并进一步探索其作为探针在研究胶体分散中的长程结构或相互作用力方面的应用。这项持续研究的一个独特之处在于发展了具有流体界面的薄膜的表面力平衡，以研究微结构对薄膜稳定性的影响。利用这项新技术，可以同时记录膜厚和毛细管压力。表面力平衡结合差示干涉显微镜将被用来研究具有曲率的薄膜，例如与乳液和泡沫系统相关的接近的小液滴或气泡之间存在的薄膜。用微分和普通的显微干涉方法进行实验，得到接触角和膜张力，从而得到膜相互作用能和由于膜内胶束结构存在而产生的分离压力。要研究的体系将包括球形和非球形胶束、混合胶束(例如在阴离子和非离子胶束溶液的混合物中)以及不同电荷的胶体粒子，如二氧化硅和乳胶。这项研究将对薄膜中与界面结构有关的结构分离压力的来源提供见解，从而提高胶体分散的稳定性。

The objective of this research is to examine, both experimentally and theoretically, the phenomenon of multilayered microstructuring or stratification in sub-micron thin liquid films produced by the use of surface active agents; further to explore its use as a probe for investigating long-range structural or interaction forces in colloidal dispersions. A unique feature of this continuing study lies in the development of a surface force balance for films with fluid interfaces for investigating the influence of microstructures on thin film stability. Using this new technique, both film thickness and capillary pressure are recorded simultaneously. The surface force balance in conjunction with the differential interference microscopy will be used to study films with curvature such as those existing between approaching small droplets or bubbles associated with emulsion and foam systems. Experiments using differential and common microinterferometic methods will be performed to obtain the contact angle and film tension and, thereby, the film interaction energy and the disjoining pressure attributable to the presence of micellar structure inside the film. Systems to be investigated will include both spherical and non- spherical micelles, mixed micelles (such as in mixtures of anionic and nonionic micellar solutions) and differently charged colloidal particles such as silica and latexes. This study will provide insights into the origin of structural disjoining pressure related to interfacial structuring in thin films which gives rise to an increased stability in colloidal dispersions.