scholarly journals Light-Induced Ring Pattern in a Dye-Doped Nematic Liquid Crystal

2021 ◽  
Vol 11 (11) ◽  
pp. 5285
Author(s):  
Marcel G. Clerc ◽  
Gregorio González-Cortés ◽  
Paulina I. Hidalgo ◽  
Lucciano A. Letelier ◽  
Mauricio J. Morel ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Phase Modulation ◽  
Order Parameter ◽  
Liquid Crystal Cell ◽  
The Self ◽  
Self Organization ◽  
Experimental Setup ◽  
Coherent Beams ◽  
Light Beams

The use of dye-doped liquid crystals allows the amplification of the coupling of light and liquid crystals. Light can induce the self-organization of the molecular order. The appearance of ring patterns has been observed, which has been associated with phase modulation. However, the morphology and dynamics of the ring patterns are not consistent with self-modulation. Based on an experimental setup with two parallel coherence beams orthogonal to a liquid crystal cell, one of which induces photo-isomerization and the other causes illumination, the formation of ring patterns is studied. To use these two coherent beams, we synthesize methylred methyl ester as a dye-dopant, which is photosensitive only to one of the light beams, and a commercial E7 liquid crystal as a matrix. Based on a mathematical model that accounts for the coupling between the concentration of the cis-state and the order parameter, we elucidate the emergence of the rings as forming patterns in an inhomogeneous medium. The bifurcation diagram is analytically characterized. The emergence, propagation of the rings, and the establishment of the ring patterns are in fair agreement with the experimental observations.

Liquid Crystal Nanoparticles- LCNANOP: A SONSII Collaborative Research Project

2008 ◽  
Vol 1134 ◽  
Author(s):  
John William Goodby ◽  
Martin Bates ◽  
Isabel Saez ◽  
Ewa Gorecka ◽  
Heinz Kitzerow ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Collaborative Research ◽  
Chemical Properties ◽  
Hierarchical Structures ◽  
The Self ◽  
Nano Particles ◽  
Self Organization ◽  
Nano Particle ◽  
Research Project

AbstractLC-NANOP is an ESF EUROCORES SONS Collaborative Research Project that is addressing an innovative approach to self-organized nanostructures by combination of a variety of organic, inorganic and metal scaffolds with the unique self-organization properties of liquid crystals to obtain liquid crystal nano-particles. LC-NANOP is concerned with the synthesis, analysis, characterization, modeling and physico-chemical properties of super- and supra-molecular systems which are formed from a nano-particle as a central scaffold, surrounded by a layer of liquid crystal. The self-organization properties of the liquid crystal coating is the driving force leading to the self-assembly of the nano-particles into secondary or tertiary hierarchical structures, with emphasis on the systematic variation of nano-particle size, chirality, shape and functionality. This bottom-up approach to nano-structuring is very powerful as it combines the extraordinary variety of morphologies that liquid crystals present with the combination of functional entities, relevant for chemical, biological, optoelectronic, and photonic tasks, etc, to create ordered nano-structures that can be controlled by external stimuli.

scholarly journals Optical Response Associated with the Orientation and Structure of Liquid Crystals with Respect to Phosphatidylcholine Concentration

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 678
Author(s):  
Yuqi Han ◽  
Yan Jiang ◽  
Wei Guo ◽  
Bing Li ◽  
Lu Zhang ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Reflectance Spectrum ◽  
Optical Response ◽  
The Self ◽  
Cholesteric Liquid Crystals ◽  
Anchoring Effect ◽  
Self Assembling ◽  
Sensitization Effect ◽  
Structure Of Liquid

Based on the anchoring effect due to the self-assembling behavior of the phospholipid molecules at the interface between the liquid crystal and water phases on the orientation of liquid crystals, the optical response associated with the orientation and structure of liquid crystals with respect to the concentration of 1,2-didodecanoyl-sn-glycero-3-phosphocholine solution has been investigated. The optical response owing to changes in the orientation and structure of the mixed cholesteric liquid crystals with respect to the change in the concentration of phosphatidylcholine has been obtained. Moreover, the feasibility of using as-prepared mixed cholesteric liquid crystals to measure the phosphatidylcholine concentration has been verified. A methodology to measure the reflectance spectrum by using mixed cholesteric liquid crystals to sensitize the phosphatidylcholine concentration has been further realized. The sensitization effect of the mixed cholesteric liquid crystals on the measurement of phosphatidylcholine concentration was also verified.

Study of optical parameters of two fluorinated isothiocyanato nematic liquid crystals exhibiting high birefringence

2014 ◽  
Vol 22 (1) ◽  
Author(s):  
T. Devi ◽  
B. Choudhury ◽  
A. Bhattacharjee ◽  
R. Dabrowski
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Laser Beam ◽  
Order Parameter ◽  
Refractive Indices ◽  
Optical Parameters ◽  
Optical Studies ◽  
High Birefringence ◽  
Two Samples ◽  
Direct Extrapolation

AbstractOptical studies have been carried out on two fluorinated isothiocyanato nematic liquid crystal (LC) compounds 4′-butylcyclohexyl-3, 5-difluoro-4-isothiocyanatobiphenyl and 4′-pentylcyclohexyl-3, 5-difluoro-4-isothiocynatobiphenyl. Transition temperatures of the two samples were confirmed using a polarizing microscope. The two LC compounds were found to exhibit fairly high clearing temperatures. Measurements of refractive indices of the two compounds were done by using thin prism method with He-Ne laser beam of wavelength 630 nm. Birefringence of the two LC compounds was calculated from the measured refractive indices. Both the compounds are found to display fairly high values of birefringence. Validation of a modified four-parameter model, based on Vuks equation describing the temperature dependence of refractive indices of the two liquid crystals, is also presented in this paper. The model is validated by fitting the experimentally measured values of refractive indices, birefringence and average refractive indices of the two nematic LCs with the theoretical values. In this paper, the calculation of order parameters of the LCs is presented by using two methods: direct extrapolation method based solely on the birefringence data and by using modified Vuks method based on Haller’s extrapolation. As observed from the obtained results, this procedure of calculating order parameter gives very reasonable results.

Soft Magnets from the Self-Organization of Magnetic Nanoparticles in Twisted Liquid Crystals

2014 ◽  
Vol 126 (46) ◽  
pp. 12654-12658 ◽  
Author(s):  
Benjamin Matt ◽  
Kirsten M. Pondman ◽  
Sarah J. Asshoff ◽  
Bennie ten Haken ◽  
Benoit Fleury ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Magnetic Nanoparticles ◽  
The Self ◽  
Self Organization ◽  
Soft Magnets

scholarly journals Impact of the Liquid Crystal Director Twisting on Two-Beam Energy Exchange in a Hybrid Photorefractive Inorganic-Liquid Crystal Cell

Crystals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1104
Author(s):  
Victor Yu. Reshetnyak ◽  
Igor P. Pinkevych ◽  
Michael E. McConney ◽  
Jonathan E. Slagle ◽  
Dean R. Evans
Keyword(s):  
Liquid Crystal ◽  
Beam Energy ◽  
Energy Exchange ◽  
Gain Coefficient ◽  
Liquid Crystal Cell ◽  
Helix Pitch ◽  
Propagation Of Light ◽  
Light Waves ◽  
Light Beams ◽  
Grating Spacing

We studied the energy transfer between light beams on the director grating in a hybrid photorefractive liquid crystal (LC) cell assuming the propagation of light waves in the cell to be in the Mauguin regime. This approach makes it possible to trace the change of the gain coefficient dependence on the director grating spacing with the change of the LC director twist. Conditions for the LC flexoelectric parameters and the director helix pitch necessary for transformation the gain coefficient dependence from the nematic to cholesteric type are obtained. The influence of the director splay and bend deformations on the gain coefficient is also studied.

An in-plane switching liquid crystal cell with weakly anchored liquid crystals on the electrode substrate

2017 ◽  
Vol 5 (18) ◽  
pp. 4384-4387 ◽  
Author(s):  
O. Sato ◽  
N. Iwata ◽  
J. Kawamura ◽  
T. Maeda ◽  
Y. Tsujii ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Liquid Crystal Displays ◽  
Polyimide Film ◽  
Liquid Crystal Cell ◽  
Crystal Cell ◽  
Hexyl Methacrylate ◽  
The One

We present the “one-side zero-anchoring in-plane switching” (OZ-IPS) mode in liquid crystal displays (LCDs) comprising an electrode substrate onto which poly(hexyl methacrylate) chains are grafted and a counter substrate coated with a rubbed polyimide film.

scholarly journals Liquid Crystals Templating

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 648 ◽  
Author(s):  
Mamatha Nagaraj
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Inorganic Materials ◽  
The Self ◽  
Thermotropic Liquid Crystals ◽  
Versatile Technique ◽  
Crystal Phases ◽  
Nanoscale Features ◽  
Mesoporous Membranes ◽  
Liquid Crystal Templating

Liquid crystal templating is a versatile technique to create novel organic and inorganic materials with nanoscale features. It exploits the self-assembled architectures of liquid crystal phases as scaffolds. This article focuses on some of the key developments in lyotropic and thermotropic liquid crystals templating. The procedures that were employed to create templated structures and the applications of these novel materials in various fields including mesoporous membranes, organic electronics, the synthesis of nanostructured materials and photonics, are described.

scholarly journals Liquid crystals of carbon nanotubes and graphene

2013 ◽  
Vol 371 (1988) ◽  
pp. 20120499 ◽  
Author(s):  
Cécile Zakri ◽  
Christophe Blanc ◽  
Eric Grelet ◽  
Camilo Zamora-Ledezma ◽  
Nicolas Puech ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Order Parameter ◽  
Orientational Order ◽  
Point Of View ◽  
General Point ◽  
Conductivity Anisotropy ◽  
Conductive Films ◽  
Experimental Approaches ◽  
New Methodologies

Liquid crystal ordering is an opportunity to develop novel materials and applications with spontaneously aligned nanotubes or graphene particles. Nevertheless, achieving high orientational order parameter and large monodomains remains a challenge. In addition, our restricted knowledge of the structure of the currently available materials is a limitation for fundamental studies and future applications. This paper presents recent methodologies that have been developed to achieve large monodomains of nematic liquid crystals. These allow quantification and increase of their order parameters. Nematic ordering provides an efficient way to prepare conductive films that exhibit anisotropic properties. In particular, it is shown how the electrical conductivity anisotropy increases with the order parameter of the nematic liquid crystal. The order parameter can be tuned by controlling the length and entanglement of the nanotubes. In the second part of the paper, recent results on graphene liquid crystals are reported. The possibility to obtain water-based liquid crystals stabilized by surfactant molecules is demonstrated. Structural and thermodynamic characterizations provide indirect but statistical information on the dimensions of the graphene flakes. From a general point of view, this work presents experimental approaches to optimize the use of nanocarbons as liquid crystals and provides new methodologies for the still challenging characterization of such materials.

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