High pressure study of the cholesteric/smectic C∗ phase transition of 4-n-hexyloxyphenyl-4′-(2'-methylbutyl)biphenyl-4-carboxylate (CE3)

The cholesteric (Ch)/smectic C∗ (Sc∗) phase transition of CE3 has been studied up to 2kbar and 115°C by a light reflection method. In contrast to the cholesteric/smectic A phase transition, which can cross over from first to second order at elevated pressure, the Ch/Sc∗ transition of CE3 was found to remain first order. This result is in agreement with most theoretical predictions. The pretransformation on the cholesteric side of the Ch/Sc∗ transition is influenced only weakly by increasing pressure. Because of the high viscosity of the smectic C∗ phase corresponding results could not be obtained on the smectic side of the transition.