Journal of the American Chemical Society, Vol.119, No.40, 9466-9477, 1997
Magnetic-field-induced orientational ordering of alkaline lyotropic silicate - surfactant liquid crystals
Macroscopically oriented silicate-surfactant liquid crystals are produced by slow cooling of lamellar and hexagonal mesophases through their isotropic-anisotropic phase transition in an 11.7 T magnetic field. Comparisons of in situ experimental and simulated H-2 NMR spectra quantify the degrees of orientational order in the silicate-surfactant Liquid crystals. The overall orientations of the mesophases with respect to the applied magnetic field depend upon the combined diamagnetic susceptibilities of the individual molecular species in the multicomponent surfactant-silicate mixtures. As a result, macroscopic alignment of these liquid crystalline systems can be controlled by adjusting their composition: lamellar or hexagonal domains are shown to adopt different orientations, according to the diamagnetic susceptibilities of different organic additives present in otherwise identical mixtures. These results demonstrate the utility of liquid crystal processing strategies for organizing inorganic-organic hybrid materials over mesoscopic and macroscopic length scales.