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Abstract
We report for the first time a gas-induced molecular excess order at the surface of the low molecular liquid crystalline substance MBBA (4-methoxybenzylidene-4′-n-butylaniline), revealed from its surface tension-temperature characteristic in CO2 at elevated pressures. Such gas-induced surface excess order has been observed both in the nematic and isotropic phase, which can be enhanced by increasing the gas pressure. It is unusual for a low molecular liquid crystal, that this surface order can be even in the isotropic phase over a wide temperature range stable when the gas pressure is high enough.
Experimentally, the surface tension measurements and the gas sorption measurements have been carried out separately under the same conditions which cover a temperature range of 0–80°C and a pressure range of 1–15 bar, by using a computer-aided measuring set-up based on the pendant drop method and a high pressure electromicrobalance, respectively.