Properties of the Broad-Range Nematic Phase of a Laterally Linked H-Shaped Liquid Crystal Dimer

TL;DR

This study reports a novel H-shaped liquid crystal dimer with an unusually broad nematic phase, exhibiting unique textural features and domain walls, confirmed as uniaxial nematic through multiple characterization techniques.

Contribution

The paper introduces a new H-shaped liquid crystal dimer with an extensive nematic temperature range and detailed analysis of its textural and structural properties.

Findings

Broad nematic phase of about 50°C

Presence of smectic clusters within the nematic phase

Domain walls caused by surface anchoring transition

Abstract

In search for novel nematic materials, a laterally linked H-shaped liquid crystal dimer have been synthesized and characterized. The distinct feature of the material is a very broad temperature range (about 50 oC) 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.