Effect of pressure on phase behavior of a thermotropic cubic mesogen

The phase behavior of an optically isotropic, thermotropic cubic mesogen 4-(ethylpentoxy)-anilinebenzylidenen-4′-carboxylic acid was investigated under pressures up to 300 MPa using a high-pressure differential thermal analyzer, a wide-angle X-ray diffractometer (WAXD) and a polarizing optical microscope (POM) equipped with a high-pressure optical cell. The cubic phase was found in the whole pressure region, although its temperature region decreased gradually with increasing pressure. The phase transition sequence, crystal (Cr)-cubic (Cub)-isotropic liquid (I) observed at atmospheric pressure, is held under pressures, while a high-temperature crystal polymorph appears under elevated pressures above about 160 MPa.