A critical overview of the influence of graphene and its analogues on nematic liquid crystals

Abstract

Two-dimensional (2D) materials and liquid crystals (LCs) originate from opposite ends of the materials spectrum, with both recognized for several sought-after properties. In line with current trends in materials science, LCs have progressively entered the realm of nanocomposites, creating new vistas for LC-based applications. Although there is considerable research on these nano-soft composites, the nano-component has predominantly been of zero- and one-dimensional nature, and integration of 2D materials into the field is an appealing upcoming research area. This review outlines such endeavours, describing the influence of 2D materials on both thermotropic and lyotropic LCs, primarily focussing on the nematic mesophase, the orientationally ordered liquid. Sections on both these LCs begin with the theoretical efforts and experimental findings on several physical properties of the 2D materials forming the LCs, or incorporated into nematics in the bulk and upon confinement in a polymer matrix, or as substrate layers for uniform orientation of the nematic director. Various applications, including the bio-related ones, are also described. Finally, we outline potential pathways along which the domain of 2D materials in LCs might advance by addressing the perceived challenges. The interspersed critical comments on the research reported aim to encourage researchers to enrich the field with comprehensive efforts.