scholarly journals Prolate and oblate chiral liquid crystal spheroids

2020 ◽  
Vol 6 (28) ◽  
pp. eaba6728
Author(s):  
Monirosadat Sadati ◽  
Jose A. Martinez-Gonzalez ◽  
Ye Zhou ◽  
Nader Taheri Qazvini ◽  
Khia Kurtenbach ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Wearable Sensors ◽  
Mechanical Strain ◽  
Orientational Order ◽  
Topological Defects ◽  
Smart Fabrics ◽  
Chiral Liquid Crystal ◽  
Smart Coatings ◽  
Optical Appearance

Liquid crystals are known to exhibit intriguing textures and color patterns, with applications in display and optical technologies. This work focuses on chiral materials and examines the palette of morphologies that arises when microdroplets are deformed into nonspherical shapes in a controllable manner. Specifically, geometrical confinement and mechanical strain are used to manipulate orientational order, phase transitions, and topological defects that arise in chiral liquid crystal droplets. Inspired by processes encountered in nature, where insects and animals often rely on strain and temperature to alter the optical appearance of dispersed liquid crystalline elements, chiral droplets are dispersed in polymer films and deformation induced by uniaxial or biaxial stretching. Our measurements are interpreted by resorting to simulations of the corresponding systems, thereby providing an in-depth understanding of the morphologies that arise in these materials. The reported structures and assemblies offer potential for applications in smart coatings, smart fabrics, and wearable sensors.

scholarly journals Topology control of human fibroblast cells monolayer by liquid crystal elastomer

2020 ◽  
Vol 6 (20) ◽  
pp. eaaz6485 ◽  
Author(s):  
Taras Turiv ◽  
Jess Krieger ◽  
Greta Babakhanova ◽  
Hao Yu ◽  
Sergij V. Shiyanovskii ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Orientational Order ◽  
Topological Defects ◽  
Density Fluctuations ◽  
Dermal Fibroblasts ◽  
Produce Cell ◽  
Surface Anchoring ◽  
Liquid Crystal Elastomer ◽  
Anisotropic Surface ◽  
Living Tissues

Eukaryotic cells in living tissues form dynamic patterns with spatially varying orientational order that affects important physiological processes such as apoptosis and cell migration. The challenge is how to impart a predesigned map of orientational order onto a growing tissue. Here, we demonstrate an approach to produce cell monolayers of human dermal fibroblasts with predesigned orientational patterns and topological defects using a photoaligned liquid crystal elastomer (LCE) that swells anisotropically in an aqueous medium. The patterns inscribed into the LCE are replicated by the tissue monolayer and cause a strong spatial variation of cells phenotype, their surface density, and number density fluctuations. Unbinding dynamics of defect pairs intrinsic to active matter is suppressed by anisotropic surface anchoring allowing the estimation of the elastic characteristics of the tissues. The demonstrated patterned LCE approach has potential to control the collective behavior of cells in living tissues, cell differentiation, and tissue morphogenesis.

Antiferroelectric Liquid Crystals from Achiral Molecules And A Liquid Conglomerate

1999 ◽  
Vol 559 ◽  
Author(s):  
David M. Walba ◽  
Eva Körblova ◽  
Renfan Shao ◽  
Joseph E. Maclennan ◽  
Darren R. Link ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Crystal Phase ◽  
Liquid Crystal Phase ◽  
Crystalline Structures ◽  
Chiral Liquid Crystal ◽  
Antiferroelectric Liquid Crystals ◽  
Liquid Crystal Structure

ABSTRACTUntil recently, it was an empirical fact that creation of a chiral liquid crystal phase required enantiomerically enriched molecules. In addition, to date known ferroelectric and antiferroelectric smectics have also been composed of enantiomerically enriched molecules. Herein are described the first examples of the formation of chiral and antiferroelectric supermolecular liquid crystalline structures from achiral molecules. In one case (apparently metastable) the liquid crystal structure is macroscopically chiral, with samples composed of heterochiral macroscopic domains: a liquid conglomerate.

scholarly journals Photophysical and Photochemical Properties of Green Fluorescent Liquid Crystalline Systems

2003 ◽  
Vol 58 (1) ◽  
pp. 45-50 ◽  
Author(s):  
Ivo Grabchev ◽  
Jean-Marc Chovelon
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Liquid Crystalline ◽  
Photophysical Properties ◽  
Orientational Order ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed ◽  
Photochemical Properties ◽  
Green Fluorescent ◽  
Naphthalimide Dye

The photophysical properties of polymer-dispersed liquid crystal systems, containing naphthalimide dye as fluorescent units are reported. Investigations have been carried out on some 1,8- naphtalimide derivatives both in isotropic and anisotropic media, and their photophysal properties have been described. The orientational order parameters of the dyes in nematic liquid crystal ZLI 1840 have been determined. The photostability of the dye/liquid crystal systems has been investigated and the effect that the substituents in the naphthalimide structure have upon the orientation of the dye was discussed.

scholarly journals Wavelength-tuneable laser emission from stretchable chiral nematic liquid crystal gels via in situ photopolymerization

RSC Advances ◽  
2016 ◽  
Vol 6 (38) ◽  
pp. 31919-31924 ◽  
Author(s):  
S. M. Wood ◽  
F. Castles ◽  
S. J. Elston ◽  
S. M. Morris
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Liquid Crystalline ◽  
Laser Emission ◽  
Mechanical Strain ◽  
Chiral Nematic

We describe a technique for creating multi-coloured liquid crystalline laser gels which may be selectively and reversibly wavelength-tuned by applying a mechanical strain.

scholarly journals DNA Origami Nano-Sheets and Nano-Rods Alter the Orientational Order in a Lyotropic Chromonic Liquid Crystal

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1695
Author(s):  
Bingru Zhang ◽  
Kevin Martens ◽  
Luisa Kneer ◽  
Timon Funck ◽  
Linh Nguyen ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Order Parameter ◽  
Liquid Crystalline ◽  
Orientational Order ◽  
Dna Origami ◽  
Nano Particles ◽  
Width Ratio ◽  
Disodium Cromoglycate ◽  
Orientational Order Parameter ◽  
Nano Rods

Rod-like and sheet-like nano-particles made of desoxyribonucleic acid (DNA) fabricated by the DNA origami method (base sequence-controlled self-organized folding of DNA) are dispersed in a lyotropic chromonic liquid crystal made of an aqueous solution of disodium cromoglycate. The respective liquid crystalline nanodispersions are doped with a dichroic fluorescent dye and their orientational order parameter is studied by means of polarized fluorescence spectroscopy. The presence of the nano-particles is found to slightly reduce the orientational order parameter of the nematic mesophase. Nano-rods with a large length/width ratio tend to preserve the orientational order, while more compact stiff nano-rods and especially nano-sheets reduce the order parameter to a larger extent. In spite of the difference between the sizes of the DNA nano-particles and the rod-like columnar aggregates forming the liquid crystal, a similarity between the shapes of the former and the latter seems to be better compatible with the orientational order of the liquid crystal.

Optical Study of Liquid Crystal Doped with Multiwalled Carbon Nanotube

2014 ◽  
Vol 13 (04) ◽  
pp. 1440001
Author(s):  
Rita A. Gharde ◽  
Sangeeta Y. Thakare
Keyword(s):  
Liquid Crystal ◽  
Carbon Nanotube ◽  
Optical Fibers ◽  
Liquid Crystalline ◽  
Effective Means ◽  
Orientational Order ◽  
Multiwall Carbon Nanotube ◽  
Multiwalled Carbon ◽  
Vis Spectroscopy ◽  
Crystal Dispersion

Liquid crystalline materials have been useful for display devices i.e watches, calculators, automobile dashboards, televisions, multi media projectors etc. as well as in electro tunable lasers, optical fibers and lenses. Carbon nanotube is chosen as the main experimental factor in this study as it has been observed that Carbon Nano Tube influence the existing properties of liquid crystal host and with the doping of CNT can enhance1 the properties of LC. The combination of carbon nanotube (CNT) and liquid crystal (LC) materials show considerable interest in the scientific community due to unique physical properties of CNT in liquid crystal. Dispersion of CNTs in LCs can provide us a cheap, simple, versatile and effective means of controlling nanotube orientation on macroscopic scale with no restrictions on nanotube type. LCs have the long range orientational order rendering them to be anisotropic phases. If CNTs can be well dispersed in LC matrix, they will align with their long axes along the LC director to minimize distortions of the LC director field and the free energy. In this paper, we doped liquid crystal (Cholesteryl Nonanoate) by a small amount of multiwall carbon nanotube 0.05% and 0.1% wt. We found that by adding carbon nanotube to liquid crystals the melting point of the mixture is decreased but TNI is increased. It has been also observed that with incereas in concentration of carbon nanotube into liquid crystal shows conciderable effect on LC. The prepared samples were characterized using various techniques to study structural, thermal and optical properties i.e PMS, FPSS, UV-Vis spectroscopy, FT-IR measurements, and DTA.

Linearly polarized electroluminescence device in which the polarized plane can be rotated electrically using a chiral liquid crystalline semiconductor

2020 ◽  
Vol 4 (7) ◽  
pp. 2137-2148 ◽  
Author(s):  
Masahiro Funahashi ◽  
Yuki Mori
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Crystal Phase ◽  
Liquid Crystal Phase ◽  
Crystalline Semiconductor ◽  
Chiral Liquid Crystal ◽  
Electroluminescence Device ◽  
Linearly Polarized ◽  
Dc Bias

The polarized plane of linearly polarized electroluminescence is rotated by DC bias application during a phase transition of a chiral liquid crystal phase.

scholarly journals Mosaics of topological defects in micropatterned liquid crystal textures

2018 ◽  
Vol 4 (11) ◽  
pp. eaau8064 ◽  
Author(s):  
Dae Seok Kim ◽  
Simon Čopar ◽  
Uroš Tkalec ◽  
Dong Ki Yoon
Keyword(s):  
Liquid Crystal ◽  
Orientational Order ◽  
Topological Defects ◽  
Smectic Phase ◽  
Dimensional System ◽  
Two Dimensional ◽  
Layer Spacing ◽  
Smectic A ◽  
Lattice Symmetry ◽  
Two Dimensional System

Topological defects in the orientational order that appear in thin slabs of a nematic liquid crystal, as seen in the standard schlieren texture, behave as a random quasi–two-dimensional system with strong optical birefringence. We present an approach to creating and controlling the defects using air pillars, trapped by micropatterned holes in the silicon substrate. The defects are stabilized and positioned by the arrayed air pillars into regular two-dimensional lattices. We explore the effects of hole shape, lattice symmetry, and surface treatment on the resulting lattices of defects and explain their arrangements by application of topological rules. Last, we show the formation of detailed kaleidoscopic textures after the system is cooled down across the nematic–smectic A phase transition, frustrating the defects and surrounding structures with the equal-layer spacing condition of the smectic phase.

Oriental behaviour of some homologues of 4-n-pentyl-phenylthio-4′-n-alkoxybenzoate doped with dichroic dye

2008 ◽  
Vol 16 (3) ◽  
Author(s):  
D. Bauman ◽  
A. Zięba ◽  
E. Mykowska
Keyword(s):  
Liquid Crystal ◽  
Order Parameter ◽  
Liquid Crystalline ◽  
Orientational Order ◽  
Polarized Light ◽  
Emission Spectra ◽  
Smectic C ◽  
Fluorescence Measurements ◽  
Dichroic Dye ◽  
Linearly Polarized

AbstractThe long-range orientational order of three members of 4-n-pentylphenylthio-4′-n-alkoxybenzoate $$ (\bar nS5) $$ series doped with a dichroic dye was studied by means of electronic absorption and fluorescence measurements. The order parameters <P2> and <P4> as well as the orientational distribution function were determined on the basis of absorption and emission spectra of linearly polarized light recorded as a function of temperature in the nematic, smectic A, and smectic C phases. An influence of the dye molecular structure on the orientational order of the dye/liquid crystal mixture was observed. Moreover, the dependence of the order parameter values on the length of the alkoxy chain in liquid crystal molecules was found. It was shown that the order parameter <P4>, obtained from fluorescence measurements, can be helpful in recognizing the second-order or weakly first-order transitions between various liquid crystalline phases.

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