ULTRATHIN FILMS OF SMECTIC LIQUID-CRYSTALS ON SOLID SUBSTRATES

Two cyanobiphenyl materials and a variety of alkyl 4'-alkenoxybiphenyl-4-carboxylates with different chain lengths have been deposited on a wide variety of substrates by evaporation in vacuo and, where possible, by the Langmuir-Blodgett technique to form multilayer films. These films have been characterized by optical microscopy, low-angle X-ray diffraction, and, where appropriate, FTIR. The materials have also been studied by DSC and under the polarizing microscope using thicker layers pressed between two glass plates, All the materials studied exhibited at least one smectic phase. It was impossible to wet any of the substrates used by the cyanobiphenyl materials and thus the films formed from these materials degenerated into droplets. The two materials having an isopropyl ester termination and one of the materials having an ethyl ester termination formed smectic phases at or near room temperature when deposited by evaporation in vacuo. Two materials could also be deposited by the Langmuir-Blodgett technique, in one case forming a bilayer structure and in the other case forming a monolayer structure.