Dielectric pretransitional effects in the isotropic phase of chiral liquid crystals

Abstract

We have performed dielectric measurements on chiral liquid crystalline systems. From the values of the static dielectric permittivity, it is observed that the dielectric pretransitional effect in the isotropic phase on approaching the isotropic to cholesteric or isotropic to blue phase transition is virtually not influenced by the chirality of the system. The relaxation times do not show anomalous behaviour near the transition, although a small overall slowing down is observed in mixtures with increasing chirality.

Acknowledgements

This work was supported by the National Fund for Scientific Research Flanders (Belgium) (FWO, Project No. G.0246.02) and by the Research Council of KU Leuven (project GOA‐4, 2002).

Notes

1. The actual mesophase (M) following the isotropic phase is not clearly identified for all the samples. Therefore the transition will be written as MI.

2. T _MI is the temperature of the last data point that belongs to the isotropic phase. Subsequent data points at lower temperatures belong to the cholesteric phase or eventually the two phase region. Since we used small temperature steps, T _MI can be regarded as the upper limit of the two phase region.