Properties of the broad-range nematic phase of a laterally linked H-shaped liquid crystal dimer

Abstract

In search for novel nematic materials, a laterally linked H-shaped liquid crystal dimer has been synthesised and characterised. The distinct feature of this material is a very broad temperature range (about 50 degrees C) of the nematic phase, which is in contrast with other reported H-dimers that show predominantly smectic phases. The material exhibits interesting textural features at the scale of nanometers (presence of smectic clusters) and at the macroscopic scales. Namely, at a certain temperature, the flat samples of the material show occurrence of domain walls. These domain walls are caused by the surface anchoring transition and separate regions with differently tilted director. Both above and below this transition temperature, the material represents a uniaxial nematic, as confirmed by the studies of defects in flat samples and samples with colloidal inclusions, freely suspended drops, X-ray diffraction and transmission electron microscopy.