Rheological properties of discotic nematic liquid crystals: graphene oxide dispersions study

Abstract

ABSTRACT In this study, the main objective is to propose an analytical method to calculate the viscosity coefficients and various rheological properties for discotic nematic liquid crystals (DNLCs). Using this approach, the viscosity coefficients for a discotic liquid crystal (DLC) have been calculated, and the rheological properties compared with the experimental results to verify the proposed method. The method has been illustrated on nematic Graphene oxide (GO) dispersions, as an example of DNLCs. GO dispersion, the most processable derivative of graphene is a DLC, and it is oxygen-functionalised graphene that has attracted enormous attention due to the unique liquid crystal (LC) and rheological properties. Shear-thinning rheological behaviour of the nematic phase of GO dispersion has opened an easy way to fabricate graphene-based devices in micro and macro scales. The results showed that the alignment viscosities from the analytical method were in very good agreement with the experimental ones. The Leslie and the Landau viscosities coefficients, the alignment viscosity, the rotational diffusivity, and other rheological properties have been calculated as a function of concentration. The Landau and Leslie viscosity coefficients calculated using the proposed analytical method can be used for stress tensor calculations in the Leslie-Ericksen theory and the Landau-de Gennes theory for modelling of DNLC.