Journal of Colloid and Interface Science, Vol.178, No.2, 638-647, 1996
An Investigation of Microstructures in Cationic/Anionic Surfactant Suspensions by Cryogenic Transmission Electron-Microscopy
Cryogenic transmission electron microscopy (cryo-TEM) has been used to image a variety of single and mixed cationic-anionic surfactant suspensions in water and in the presence of salt. A diverse range of microstructures have been observed, ranging from thread-like and spherical micelles in the single surfactant systems to spherical unilamellar vesicles, multilamellar vesicles, and bilayer microtubules in the mixtures. As the counterion binding strength is increased, the vesicles grow, pointing to a straightforward way by which vesicle sizes can be tuned. Size variations of the unilamellar vesicles, obtained from cryo-TEM are distinctly non-Gaussian. Formation of these vesicles in low concentrations of a divalent salt produces large aggregates, but does not destroy the bilayers.