X-ray studies of the surface and bulk structure of the isotropic and nematic phase of a lyotropic liquid crystal
- Department of Physics and the Division of Applied Science, Harvard University, Cambridge, Massachusetts 02138 (US)
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (US)
We have used x-ray specular reflection to study the structure of the air--liquid-crystal interface of the lyotropic liquid crystal formed from binary mixtures of cesium perfluoro-octanoate (CsPFO) and water. In the isotropic phase the surface is coated with a monolayer of CsPFO separated by layers of water from one or more smectic bilayers of CsPFO. As for the case of thermotropic liquid crystals, the isotropic-to-nematic phase transition has no effect on the surface structure, and as the temperature is lowered towards the nematic--to--smectic-{ital A} transition temperature, the number of surface-induced smectic layers increases dramatically (e.g., approximately 100 layers were observed). Theoretical modeling of the reflectivity excludes the possibility that the surface bilayers are arrays of micelles. X-ray scattering from critical smectic short-range order in the bulk, studied by tuning the spectrometer away from the specular condition, indicates that the scattering is fundamentally different from short-range smectic order in thermotropic systems.
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 5662807
- Journal Information:
- Physical Review, A; (USA), Vol. 43:12; ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
LIQUID CRYSTALS
PHASE STUDIES
SURFACE PROPERTIES
CESIUM COMPOUNDS
LIGHT SCATTERING
REFLECTIVITY
X RADIATION
ALKALI METAL COMPOUNDS
CRYSTALS
ELECTROMAGNETIC RADIATION
FLUIDS
IONIZING RADIATIONS
LIQUIDS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
SCATTERING
360602* - Other Materials- Structure & Phase Studies
360603 - Materials- Properties