Dilatometry of the discotic mesogen 2,3,6,7,10,11-hexa-n-octanoyloxytriphenylene (HAT-C8)

Abstract

The title compound HAT-C8 exhibits a columnar to isotropic phase transition at 402·16 K. Dilatometric studies of pure HAT-C8 as a function of temperature show the higher temperature isotropic phase to be denser than the lower temperature columnar mesophase. The fractional volume change is similar to that observed for benzene hexa-n-alkanoates, but of opposite sign. Such anomalous density changes are rare. Since the columnar-isotropic transition entropy has been measured, dp/dT has been estimated from the Clapeyron equation.