Abstract
There are two pressure dependences in the phase stability of the cubic phase of optically isotropic, thermotropic liquid crystals possessing linear molecular structures. In the first case, the cubic phase is destabilized by applying pressure, and finally disappears under high pressure, as seen in 4'-hexadecyloxy-3'-nitrobiphenyl-4-carboxylic acid ANBC(16), 1, 2-bis-(4-n-octyloxy-and 4-n-decyloxybenzoyl)hydrazine, BABH(8) and BABH(10). Triple point can be seen in their T-P phase diagrams, indicative of upper limit of pressure for the formation of the cubic phase. In the second case, the cubic phases are held stable under high pressure. The cubic phases of the 14PC5F polycatenar compound and EPABC liquid crystal belong to the second class. We introduce the experimental results of different phase behavior of these cubic phases under pressure.
