Optically determined mesomorphic transitions in cholesteryl stearate at high pressure

Abstract

A new optical method to determine phase transitions at high pressure is described in detail. The method is applied to mesomorphic transitions in cholesteryl stearate. The solid-isotropic liquid and cholesteric-isotropic liquid transition temeperatures vary linearly with pressure is the range of 1 to 800 bar. The volume change computed at 1 bar through the Clapeyron equation is 55 cm^3 mol^-1 for the solid-isotropic liquid transition and l.2 cm^3 mol^-1 for the cholesteric-isotropic liquid transition. The ratio of the latter volume change to the former is 0.022, being close to that for many nematic phases.