3C11 Phase Transition Behavior of Cubic Liquid Crystalline Compounds ANBC-n under Hydrostatic Pressure

Abstract

The phase behavior of thermotropic cubic mesogens 4'-n-alkoxy-3'-nitrobiphenyl-4-carboxylic acids (ANBC-n, where n is the number of carbon atoms in the alkoxy group) with n = 16, 20, and 22 was investigated under hydrostatic pressures up to 400 MPa primarily by high-pressure differential thermal analysis. A general trend obtained for the cubic (Cub) phases is that they are destabilized with increasing pressure ; the temperature vs pressure diagram (on heating) for ANBC-16 exhibits the SmC-Cub-SmA triple point at 54 MPa and 205 ℃ and the diagram for ANBC-20 shows the SmC-Cub-Iso triple point at 309 MPa and 254 ℃. However, interestingly, the Cub phase of ANBC-22 still remains at the highest pressure examined (up to 400MPa).