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ABSTRACT
We study the effects of graphene nanoparticles on dielectric and material properties of 5CB nematic: 4-he-4ʹ-cyanobiphenyl. Using the experimental methods of dielectric measurements and polarising microscopy we show that the dispersed NPs decrease the nematic-isotropic liquid transition temperature. The doped NPs also decrease the dielectric anisotropy, elasticity and viscosity of the material. We propose that all mentioned decreases are caused by the distortion of LC molecules orientational order by disc-shaped graphene NPs, which have ‘weak’ anisotropy. We report that the threshold voltage stays almost unaffected by the doped GNPs. On the contrary, the doped NPs significantly (4–5 times) decrease the switching-off time of the nematic. This fact makes the studied systems promising candidates for their applications in electro-optical devises. We also test the validity of the classical Maier-Saupe theory, which predicts a linear dependence of the elasticity vs the square root of the order parameter. By comparing experimental data with the theoretical prediction, we show that the pure nematic’s behaviour follows the classical prediction. However, the doped samples behaviour departs from the classical prediction..
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Acknowledgements
KKV thanks the College of Arts and Sciences at SIUE and Dean’s office, for providing start-up funds, and granting sabbatical leave for accomplishing this project. KKV and BB thank the Department of Physics and the Chairs: Prof. Hamad (former) and Prof. Glassman (current) for overall support. BB is grateful to SIUE Undergraduate Research and Creative Activities (URCA) program and the Coordinator: Prof. Pawlow, for providing financial support during the accomplishment of the project.
Disclosure statement
No potential conflict of interest was reported by the author(s).