Direct Visualization of Amphiphilic Phases by Video Enhanced Microscopy and Cryo-Transmission Electron Microscopy

Abstract

Establishing the phase diagram of a surfactant-water system is a relatively simple matter; visual observations between crossed polarizers [1] are combined with data obtained from polarizing microscopy [2] and other techniques to generate diagrams such as shown in Fig. 1. The determination of the structure within these phases is more complicated. Commonly used techniques such as NMR, and X-ray, light and neutron scattering go a long way towards elucidating average structural tendencies in surfactant phases. However, since these non-invasive, though indirect, techniques rely on mathematical models for interpretation — models with a priori assumptions of simple geometric form (spheres, cylinders, planes, etc.) for surfactant aggregates — they cannot provide detailed information on systems with complicated topologies. For example, paired disclinations in lamellar phases [3] and self-similar structures, which scale over many orders of magnitude, of a kind to be illustrated below, are difficult, if not impossible to study by scattering techniques.