scholarly journals Binary Mixture Composed of Nematic Liquid Crystal and Carbon Nanotubes: A Theoretical Description

2019 ◽  
Author(s):  
Vlad Popa-Nita ◽  
Robert Repnik
Keyword(s):  
Carbon Nanotubes ◽  
Liquid Crystal ◽  
Binary Mixture ◽  
Nematic Liquid Crystal ◽  
Theoretical Description

scholarly journals Mechanisms of Chiral Transfer in Optically Active Dopant – Nematic Liquid Crystal Systems

2020 ◽  
Vol 20 (4) ◽  
pp. 6-26
Author(s):  
V. A. Burmistrov ◽  
V. V. Aleksandriiskii ◽  
I. V. Novikov ◽  
O. I. Koifman
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Self Assembly ◽  
Liquid Crystalline ◽  
High Efficiency ◽  
Stationary Phases ◽  
Theoretical Description ◽  
Optically Active ◽  
Axial Coordination ◽  
Chiral Dopants

Induction of helical mesophases by incorporating chiral dopants into the nematics matrix is the promising modern trends in the chemistry of liquid crystals. This process is associated with a unique phenomenon - an amplification of chirality in liquid-crystalline phases, which ensures the detection of enantiomers by their chiral induction, much more sensitive than other methods. The relevance of this approach is due to the need to create perspective electro-optical devices operating with ultra-low control voltages based on twist effects, chromatographic stationary phases with high chiral selectivity, flexible magnets, photo-sensitive nanostructures, and other smart LC materials. The successful solution of these problems is impossible without experimental research and theoretical comprehension of the mechanisms of third level chiral transfer optically active dopant – nematic liquid crystal. In the last decade, a large number of works have appeared on the solution of these problems. This review is devoted to a generalization of the experimental results and a theoretical description of the transfer of molecular chirality to orientationally ordered systems with the participation of both chiral molecular substituents with an asymmetric carbon atom and planar or quasi-planar fragments chirally distorted relative to each other. The stereochemical aspects of induction associated with the structural correspondences of the dopant and nematic liquid crystal, as well as the main classes of optically active additives, are discussed. Application of metal complexes, both Werner and macroheterocyclic, are presented. Special attention is paid to the results of the mechanisms study of chiral transfer due to various intermolecular interactions: hydrogen bonding, axial coordination, and the formation of inclusion compounds. The high efficiency of induction of spiral mesophases has been demonstrated with a combination of different self-assembly mechanisms in liquid crystal - chiral additive systems.

scholarly journals Molecular dynamics of a binary mixture of twist-bend nematic liquid crystal dimers studied by dielectric spectroscopy

2016 ◽  
Vol 93 (6) ◽  
Author(s):  
Beatriz Robles-Hernández ◽  
Nerea Sebastián ◽  
Josep Salud ◽  
Sergio Diez-Berart ◽  
David A. Dunmur ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Liquid Crystal ◽  
Binary Mixture ◽  
Nematic Liquid Crystal ◽  
Dielectric Spectroscopy

DYNAMIC RESPONSE OF CARBON NANOTUBES DISPERSED IN NEMATIC LIQUID CRYSTAL

NANO ◽  
2007 ◽  
Vol 02 (01) ◽  
pp. 41-49 ◽  
Author(s):  
SANG YOUN JEON ◽  
KYUNG AH PARK ◽  
IN-SU BAIK ◽  
SEOK JIN JEONG ◽  
SEOK HO JEONG ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Liquid Crystal ◽  
Electric Field ◽  
Dynamic Response ◽  
Nematic Liquid Crystal ◽  
Density Functional ◽  
Strong Electric Field ◽  
Optical Microscope ◽  
Analysis Of Dynamics ◽  
Vertical Cell

The alignment and dynamic response of carbon nanotubes (CNTs) in nematic liquid crystal (NLC) medium induced by strong electric field have been observed through polarizing optical microscope. Density-functional calculations suggest that LC molecule anchors helically to the CNT wall to enhance π-stacking with a binding energy of nearly -2.0 eV due to a considerable amount of charge transfer from LC molecule to CNT, resulting in the formation of excess charges and permanent dipole moment in CNTs. Under strong electric field, the motion of CNTs distorted the director of adjacent LC molecules. Our detailed analysis of dynamics revealed that the four-lobe textures in vertical cell and two vertical stripes in in-plane switching cell were strongly correlated, i.e., the side view of textures by the vertical motion of CNTs in vertical cell was similar to the textures in in-plane switching cell. Interestingly, the magnitude of textures in microscope was strongly dependent on the size of CNTs and the applied field strength. The statistical size distribution of textures similar to that of CNTs provided information for the degree of dispersion of CNTs.

Chiral conglomerates observed for a binary mixture of a nematic liquid crystal trimer and 6OCB

Soft Matter ◽  
2015 ◽  
Vol 11 (45) ◽  
pp. 8827-8833 ◽  
Author(s):  
Atsushi Yoshizawa ◽  
Yusuke Kato ◽  
Haruna Sasaki ◽  
Yoichi Takanishi ◽  
Jun Yamamoto
Keyword(s):  
Liquid Crystal ◽  
Binary Mixture ◽  
Nematic Liquid Crystal ◽  
Twist Conformation ◽  
Layer Deformation

Interactions between a phenylpyrimidine unit of trimer 1 and a cyanobiphenyl unit of 6OCB can produce a twist conformation of the central biphenyl of the trimer, which induces chiral segregation and layer deformation to drive the chiral conglomerates.

Carbon Nanotubes Blended Nematic Liquid Crystal for Display and Electro-Optical Applications

2021 ◽  
Vol 2 (4) ◽  
pp. 466-481
Author(s):  
Bhupendra Pratap Singh ◽  
Samiksha Sikarwar ◽  
Kamal Kumar Pandey ◽  
Rajiv Manohar ◽  
Michael Depriester ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Orientational Order ◽  
Isotropic Phase ◽  
Multi Walled Carbon Nanotubes ◽  
Vertically Aligned ◽  
Higher Temperature ◽  
Optical Applications ◽  
Walled Carbon Nanotubes

In this paper, we investigate a commercial nematic liquid crystal (LC) mixture namely E7 dispersed with small concentrations of multi-walled carbon nanotubes (MWCNTs). The dielectric and electro-optical characterizations have been carried out in the homogeneously and vertically aligned LC cells. The electro-optical response of LC molecules has been enhanced by 60% after the addition of MWCNTs, which is attributed to the reduced rotational viscosity in the composites. MWCNTs act like barricades for ionic impurities by reducing them up to ∼34.3% within the dispersion limit of 0.05 wt%. The nematic–isotropic phase transition temperature (TNI) of the E7 LC has also been shifted towards the higher temperature, resulting in a more ordered nematic phase. The enhanced birefringence and orientational order parameter in the LC-MWCNTs are attributed to π-π electron stacking between the LC molecules and the MWCNTs. The outlined merits of the LC-MWCNTs composites evince their suitability for ultrafast nematic-based electro-optical devices.

Structural evolution and dielectric properties of suspensions of carbon nanotubes in nematic liquid crystals

2017 ◽  
Vol 19 (25) ◽  
pp. 16456-16463 ◽  
Author(s):  
S. Tomylko ◽  
O. Yaroshchuk ◽  
O. Koval'chuk ◽  
N. Lebovka
Keyword(s):  
Carbon Nanotubes ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Dielectric Properties ◽  
Nematic Liquid Crystal ◽  
Nematic Liquid Crystals ◽  
Structural Evolution ◽  
Percolation Transition ◽  
Electrical Percolation

Smeared electrical percolation transition in suspensions of carbon nanotubes in nematic liquid crystal was revealed. Four stages of structural evolution were identified.

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