Nanocomposites of 2D-MoS2 Exfoliated in Thermotropic Liquid Crystals

Abstract

Atomically thin MoS2 nanosheets are of interest due to unique electronic, optical, and catalytic properties that are absent in the bulk material. Methods to prepare nanosheets from bulk material that facilitate studies of 2D-MoS2 and the fabrication of useful devices have consequently assumed considerable importance. Here, we report the simultaneous exfoliation and stable dispersion of MoS2 nanosheets in a liquid crystal. Exfoliation of bulk MoS2 in mesogen-containing solutions produced stable dispersions of 2D-MoS2 that retained suspension stability for several weeks. Solvent removal in cast films yielded nanocomposites of 2D-MoS2. Preservation of single- and few-sheet MoS2 was confirmed utilizing UV-vis and Raman spectroscopy in the nematic and isotropic fluid states of the system and, remarkably, in the solid crystal as well. Importantly, the MoS2 nanosheets remained welldispersed upon polymerization of the reactive mesogen to form a liquid crystal polymer. The ability to stably disperse 2D-MoS2 in a structured fluid opens up new possibilities for studying anisotropic properties of MoS2 and for exploiting such properties in responsive materials.