Effect of biaxiality on chirality in chiral nematic liquid crystals.

Biaxiality and chirality are two of the most interesting topics in materials and biological science, particularly in liquid crystals. What is even more interesting is that these two properties are related. It was theoretically predicted that morphological chirality is impossible without morphological biaxiality in chiral nematic liquid crystals. We experimentally study the effect of biaxiality on chirality. We show that when achiral liquid crystal dimers with large molecular biaxiality are doped into chiral nematic liquid crystals, their helical pitch is significantly decreased. We have also observed an abnormal fingerprint texture of the chiral nematic liquid crystal doped dimers, which suggests morphological biaxiality. Our experimental results support the biaxial theory of chiral nematic liquid crystals.