Condensed Film Formation and Molecular Packing in Cationic Surfactant-Cholesterol and Zwitterionic Surfactant-Cholesterol Systems at the Hexane/Water Interface

Recent progress in application of surface X-ray scattering techniques to soft interfacial films

X-ray reflection (XR) and surface grazing incidence X-ray diffraction GIXD) techniques have traditionally been used to evaluate the structure of soft interfacial films. In recent years, the use of synchrotron radiation and two-dimensional detectors has enabled high resolution and high speed measurements of interfacial films, which makes it possible to evaluate more detailed and complex interfacial film structures and adsorption dynamics. In this review, we will provide an overview of recent progress in structural characterization of simple oil/water interfaces, interfacial films of biologically relevant materials, oil/water interfaces for extraction of rare metal ions, and adsorption of nanoparticles. Examples of the application of time-resolved XR methods and surface sensitive techniques such as GISAXS and surface X-ray fluorescence analysis will also be presented.

Surfactant Adsorption Layers: Experiments and Modeling

During recent years, great progress has been made in understanding the adsorption of surfactants at liquid interfaces. In addition to tensiometry, new efficient methodologies have been developed, in particular interfacial selective optical methods which allow direct access to the adsorbed amounts and interfacial layer compositions. In addition to these new experimental tools, the thermodynamic description by equations of state now allows one to provide a quantitative picture of surfactant interfacial layers. This is most notable for surfactant layers at water/oil interfaces. Additional knowledge about the structure of interfacial layers was gained through different types of molecular modeling. Improved interrelationships between these three aspects are the challenges for current and future work. Particular attention must be paid to dilational interfacial rheology studies, as these mechanical quantities are much more sensitive to small changes in the interfacial composition and structure.