INVESTIGATION OF THERMAL AND ANALYTICAL PROPERTIES OF 2 NEMATIC LIQUID-CRYSTALS BY GAS-CHROMATOGRAPHY

Thermal and analytical properties of two liquid crystals containing in ternal [2-nitro, 3-methyl 4-(4-heptylbenzoyloxy) 4'-methylazobenzene] and external NO2[2-3-dimethyl 4-(4-heptylbenzoyloxy) 4'-nitro-azobenze ne] have been investigated by gas chromatography. Transitions temperat ures are determined by inverse gas chromatography using standard colum ns. Good agreement with values determined by differential scanning cal orimetry are found. Analytical capabilities of the two liquid crystals are shown in glass capillary columns. Compared to examples in the lit erature, the crystals used separated different kinds of solutes. In ad dition, high molecular mass solutes were eluted at relatively low temp eratures. Typical separations are observed for hydrocarbon positional isomers, aromatic hydrocarbons, geometric isomers, and volatile aroma compounds. Comparison between the performance of internal and external , NO2-liquid crystals is made.