PA19 Does the Biaxial Nematic Exist in Bent-Core Mesogens?

Abstract

If the bent-core molecules exhibit nematic phases, they could have biaxiality due to their molecular shapes. Recently a liquid crystal material containing a thiazole unit as a central core was synthesized and found to exhibit an interesting nematic phase. Under an optical microscope, the Schlieren textures were observed in the nematic phase of a homeotropically aligned cell. In the nematic phase range, we observed a spontaneous orientational change associated with characteristic texture changes, which may provide the information of the nature of the nematic phase. Two reflections were observed at a small angle corresponding to a layer periodicity even in the nematic phase, suggesting the existence of a cybotactic formation of the layer structure. In aligned samples, each peak splits into two. Based on these experimental observations, the possible existence of the biaxial nematic phase will be discussed.