Stabilization of Twisted-Rope Like Domains in Cholesteric Mesophase formed by Novel Cholesterol based Liquid Crystal Molecule

Abstract

The present work explores a novel cholesterol based liquid crystal (LC) molecule exhibiting high temperature Blue Phase (BP III), followed by a wide range cholesteric (N*) mesophase characterized by bright blue coloration arising from Braggs-like selective reflection. As temperature decreases, the N* transitions into the twist grain boundary (TGBA) mesophase, which is then followed by a smectic A phase. This mesomorphic behavior is explored using optical and dielectric studies, which show a wide temperature region, where the N* and TGBA phase co-exists together. This co-existence eventually leads to the stabilization of micrometer sized twisted-rope like domains. They are observed during the heating cycle in the N* mesophase using a wedge LC cell and existed till the isotropic transition temperature. The stability and length of these twisted domains are found to be dependent upon the thickness of the cell, and the nature of the alignment layer. This is the first experimental observation of such self-assembled structures being stabilized in the N* mesophase. Such stimuli-controlled micrometer sized twisted structures open new pathways for tunable optical components, templated self-assembly routes toward chiral micro-and nanostructured materials, and chirality controlled microstructures.