Pressure induced mesomorphism

Abstract

The paper reports the discovery of mesomorphism induced by pressure in materials that do not exhibit the liquid crystalline phase at atmospheric pressure. This observation verifies a prediction of the theory of melting of molecular crystals.

Experiments were conducted on the first two members of the p-n- alkoxybenzoic acid series. These two compounds, the methoxy- and ethoxybenzoic acids, do not form liquid crystals at atmospheric pressure whereas the third and higher homologues do. However, as the pressure is raised both compounds exhibit mesophases, initially a nematic phase and then, at higher pressures, a smectic phase as well. Experimental phase diagrams are presented which establish for the first time the existence of the solid-nematic-isotropic and solid- smectic-nematic triple points in single component systems.