Tuning liquid crystal properties with ZnO nanodiscs: a study on order parameter and conductivity

Anisotropic nanostructures dispersed in nematic liquid crystal, 4-(trans-4'-pentylcyclohexyl)-benzonitrile (PCH5), tend to improve the properties of host nematic liquid crystal owing to its structure and strong dipolar interactions. The experimental investigations of such composite systems are intriguing as well as challenging. Here, we have presented a systematic experimental study of effect of incorporation of two-dimensional anisotropic nanostructure, i.e., nanodisc on properties of room temperature nematic liquid crystal. Zinc oxide nanodiscs (ZD) of thickness ∼ 50 nm and diameter ∼ 200 nm are synthesized using hydrothermal method and characterized. Dispersion of zinc oxide nanodiscs in PCH5 is observed to increase the dielectric anisotropy and elastic constants which indicate enhancement in the order parameter of the composite system as compared to host nematic liquid crystal. Bulk ac conductivity is also observed to be decreasing by ∼60% by dispersion of zinc oxide nanodiscs in host liquid crystal. The increase in the ratio of bend to splay elastic constant makes the ZD composites of PCH5 potential candidates for higher multiplexing devices.