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Title: Nano-electromechanical rotation of graphene and giant enhancement in dielectric anisotropy in a liquid crystal

A nematic liquid crystal (LC) is doped with dilute concentrations of pristine monolayer graphene (GP) flakes, and the LC + GP hybrids are found to exhibit a dramatic increase in the dielectric anisotropy. Electric field-dependent conductance studies reveal that the graphene flakes follow the nematic director that mechanically rotates on increasing an applied electric field. Further studies show that the π–π electron stacking, between the graphene's honeycomb structure and the LC's benzene rings, stabilizes pseudo-nematic domains that collectively amplify the dielectric anisotropy by improving the orientational order parameter in the nematic phase. These anisotropic domains interact with the external electric field, resulting in a nonzero dielectric anisotropy in the isotropic phase as well. The enhancement in dielectric anisotropy, due to the LC–graphene coupling, is found to have subsequent positive impacts on the LC's orientational threshold field and elasticity that allows the nematic director to respond quicker on switching the electric field off.
Authors:
; ;  [1]
  1. Soft Matter and Nanomaterials Laboratory, Department of Physics, The United States Naval Academy, Annapolis, Maryland 21402 (United States)
Publication Date:
OSTI Identifier:
22402455
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 20; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANISOTROPY; BENZENE; DIELECTRIC MATERIALS; DOPED MATERIALS; ELECTRIC FIELDS; ELECTROMECHANICS; ELECTRONS; GRAPHENE; HEXAGONAL SYSTEMS; HYBRIDIZATION; LIQUID CRYSTALS; ROTATION