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.