Synthesis and photoswitching properties of liquid crystals derived from myo-inositol

RSC Advances ◽  
2014 ◽  
Vol 4 (66) ◽  
pp. 35089-35098 ◽  
Author(s):  
Md Lutfor Rahman ◽  
Mashitah Mohd Yusoff ◽  
Sandeep Kumar
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Optical Storage ◽  
Isotropic Phase ◽  
Storage Devices ◽  
The Creation ◽  
Bright Area

A new myo-inositol-based liquid crystal can be used for the creation of optical storage devices. The dark area is the UV-irradiated area forming a disordered isotropic phase, whereas the bright area protected from the light by using a mask remains in the ordered phase.

Synthesis of new U-shaped azobenzene liquid crystals for photoswitching properties

RSC Advances ◽  
2015 ◽  
Vol 5 (106) ◽  
pp. 87019-87029 ◽  
Author(s):  
Md Lutfor Rahman ◽  
Shaheen M. Sarkar ◽  
Mashitah M. Yusoff ◽  
Sandeep Kumar ◽  
Carsten Tschierske
Keyword(s):  
Liquid Crystals ◽  
Optical Storage ◽  
Isotropic Phase ◽  
Storage Devices ◽  
Green Area ◽  
Gray Circle

New U-shaped azobenzene liquid crystals can be used for creation of optical storage devices. Gray circle in the middle is the UV irradiated area to form disordered isotropic phase whereas blue-green area is protected from the light by mask remains.

scholarly journals Stable and Metastable Patterns in Chromonic Nematic Liquid Crystal Droplets Forced with Static and Dynamic Magnetic Fields

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 138 ◽  
Author(s):  
Jordi Ignés-Mullol ◽  
Marc Mora ◽  
Berta Martínez-Prat ◽  
Ignasi Vélez-Cerón ◽  
R. Santiago Herrera ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Boundary Conditions ◽  
Isotropic Phase ◽  
Director Field ◽  
Line Defects ◽  
The One ◽  
Bulk Structures ◽  
Microscopy Images

Spherical confinement of nematic liquid crystals leads to the formation of equilibrium director field configurations that include point and line defects. Driving these materials with flows or dynamic fields often results in the formation of alternative metastable states. In this article, we study the effect of magnetic field alignment, both under static and dynamic conditions, of nematic gems (nematic droplets in coexistence with the isotropic phase) and emulsified nematic droplets of a lyotropic chromonic liquid crystal. We use a custom polarizing optical microscopy assembly that incorporates a permanent magnet whose strength and orientation can be dynamically changed. By comparing simulated optical patterns with microscopy images, we measure an equilibrium twisted bipolar pattern within nematic gems that is only marginally different from the one reported for emulsified droplets. Both systems evolve to concentric configurations upon application of a static magnetic field, but behave very differently when the field is rotated. While the concentric texture within the emulsified droplets is preserved and only displays asynchronous oscillations for high rotating speeds, the nematic gems transform into a metastable untwisted bipolar configuration that is memorized by the system when the field is removed. Our results demonstrate the importance of boundary conditions in determining the dynamic behavior of confined liquid crystals even for configurations that share similar equilibrium bulk structures.

Platinum Orthometalated Liquid Crystals Compared with Their Palladium Analogues. First Optical Storage Effect in an Organometallic Liquid Crystal

1996 ◽  
Vol 8 (9) ◽  
pp. 2375-2381 ◽  
Author(s):  
Julio Buey ◽  
Laura Díez ◽  
Pablo Espinet ◽  
Heinz-S. Kitzerow ◽  
Jesús A. Miguel
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Optical Storage ◽  
Storage Effect

scholarly journals New complexes of liquid crystal discotic triphenylenes: induction of the double gyroid phase

2021 ◽  
Author(s):  
Olga A Otmakhova ◽  
Alexey Piryazev ◽  
Galina N Bondarenko ◽  
Georgii A. Shandryuk ◽  
Alexey Merekalov ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Charge Transfer ◽  
Liquid Crystals ◽  
Electron Donor ◽  
Charge Transfer Complexes ◽  
Flexible Instrument ◽  
Donor Acceptor ◽  
Double Gyroid ◽  
The Creation

Electron donor-acceptor liquid crystals have been attracting considerable attention due to possible applications in optoelectronics and photonics. The creation of such charge transfer complexes is a powerful and flexible instrument...

Collective and Individual Molecular Nonlinear Photonics of Liquid Crystals

2003 ◽  
Vol 12 (02) ◽  
pp. 277-289 ◽  
Author(s):  
I. C. Khoo ◽  
Andres Diaz ◽  
J. Ding ◽  
K. Chen ◽  
Y. Zhang
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Nematic Liquid Crystals ◽  
Isotropic Phase ◽  
Optical Elements ◽  
Fiber Arrays ◽  
Nonlinear Responses ◽  
Upper Limit ◽  
Phase Liquid ◽  
Nonlinear Light Scattering

This review will examine the origins of nonlinear light scattering processes in nematic liquid crystals, and explore various nonlinear photonic processes associated with optically induced director axis reorientation effects. Our theoretical prediction shows that the upper limit of nematic liquid crystal reorientation nonlinearity can be as high as 1000 cm2/W. The supra-nonlinear responses of nematic liquid crystals enable various self-action or electro-optical guiding, mixing, switching and modulation of light with unprecedented low power thresholds. Owing to the broadband birefringence of NLC, we expect to realize optical elements/devices capable of similar multi-functional operations throughout the visible — infrared regime. We also discuss the optical limiting action of isotropic-phase liquid crystal filled nonlinear fiber arrays.

scholarly journals Study of Structural Changes in Nematic Liquid Crystals Doped with Magnetic Nanoparticles Using Surface Acoustic Waves

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1023
Author(s):  
Peter Bury ◽  
Marek Veveričík ◽  
František Černobila ◽  
Peter Kopčanský ◽  
Milan Timko ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Magnetic Nanoparticles ◽  
Electric Fields ◽  
Acoustic Waves ◽  
Structural Changes ◽  
Surface Acoustic Waves ◽  
Theoretical Background ◽  
Isotropic Phase ◽  
Structure Of Nanoparticles

The surface acoustic waves (SAWs) were used to study the effect of magnetic nanoparticles on nematic liquid crystal (NLC) behavior in weak magnetic and electric fields. The measurement of the attenuation of SAW propagating along the interface between piezoelectric substrate and liquid crystal is showed as an effective tool to study processes of structural changes. The magnetic nanoparticles Fe3O4 of nanorod shape and different low volume concentration were added to the NLC (4-(trans-4′-n-hexylcyclohexyl)-isothiocyanatobenzene (6CHBT)) during its isotropic phase. In contrast to undoped liquid crystals the distinctive different SAW attenuation responses induced by both magnetic and also electric fields in studied NLC samples were observed suggesting both structural changes and the orientational coupling between both magnetic and electric moments of nanoparticles and the director of the NLC molecules. Experimental measurements including the investigation under linearly increasing and/or jumped magnetic and electrical fields, respectively, as well as the investigation of temperature and time influences on structural changes were done. The investigation of the SAW anisotropy gives supplemental information about the internal structure of nanoparticles in investigated NLCs. In addition, some magneto-optical investigations were performed to support SAW results and study their stability and switching time. The analysis of observed SAW attenuation characteristics confirmed the role of concentration of magnetic nanoparticles on the resultant behavior of investigated NLC compounds. Obtained results are discussed within the context of previous ones. The theoretical background of the presented SAW investigation is introduced, too.

Photorefractive Effect in Nematic Liquid Crystal Cell with Sandwiched Structure

2001 ◽  
Vol 709 ◽  
Author(s):  
Hyun-Wuk Kim ◽  
Jong-Duk Kim
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Nematic Liquid Crystal ◽  
Capillary Flow ◽  
Photorefractive Effect ◽  
Isotropic Phase ◽  
Optical Responses ◽  
Molecular Ordering ◽  
Photorefractive Effects ◽  
Sandwiched Structure

ABSTRACTOptical responses and orientational photorefractivities of nematic liquid crystal cells doped with fullerene were investigated with a sandwiched structure. The photorefractive effect was attributed to the reorientation and switching of liquid crystals using a photoalignment layer for vertical alignment. When nematic liquid crystals were injected at a nematic phase, a better cell texture could be obtained due to the capillary flow-induced orientation effect. Samples with this method showed the higher photorefractive effects than those injected at an isotropic phase. Therefore, the state of molecular ordering is important for the orientational photorefractive effects.

Formation of Polymer Stabilized Ferroelectric Liquid Crystals using a Fluorinated Diacrylate

1999 ◽  
Vol 559 ◽  
Author(s):  
C. Allan Guymon ◽  
Christopher N. Bowman ◽  
Christopher N. Bowman
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Polymer Network ◽  
Isotropic Phase ◽  
Ferroelectric Liquid Crystals ◽  
Smectic C ◽  
Electro Optic ◽  
Polymerization Behavior ◽  
Mechanically Stabilized ◽  
Polymer Stabilized

ABSTRACTFerroelectric liquid crystals (FLCs) have shown great potential for use in electro-optic and display technology due to their inherently fast switching speeds and bistability. Recently, considerable research has been devoted to FLCs mechanically stabilized by a polymer network. The network is formed typically by in situ polymerization of a monomer dissolved in the FLC. Because of the inherent order in the FLC, the polymerization behavior may be significantly different than what might be expected in solution polymerizations. These deviations result largely from the segregation properties of the monomer in the liquid crystal. One class of monomers, namely fluorinated acrylates, is a likely candidate for inducing novel segregation, polymerization and electro-optic behavior in polymer stabilized ferroelectric liquid crystals (PSFLCs). The use of fluorinated moieties has a significant impact on the phase and polymerization behavior of liquid crystal systems. This study focuses on the polymerization of a fluorinated diacrylate, octafluoro 1,6-hexanediol diacrylate (FHDDA), to form PSFLCs and the consequent impact of the polymerization on the ultimate performance. Interestingly, as the temperature is increased and the order of the system decreases, a dramatic increase in the polymerization rate is observed. This increase is especially prominent for polymerizations in the smectic C* phase for which the rate is more than five times that exhibited at much higher temperatures in the isotropic phase. As with other monomer/FLC systems, the segregation of the monomer plays a role in this polymerization behavior as the monomer segregates between the smectic layers of the liquid crystal. The segregation properties also significantly impact the ultimate electro-optic properties. Both ferroelectric polarization and response time of the PSFLC change markedly with different polymerization temperatures, and approach values very close to those of the neat FLC under appropriate polymerization conditions. This behavior not only provides a unique mechanism for rate acceleration in PSFLCs, but also paves the way for new methods to optimize performance in these materials.

Sign in / Sign up

Export Citation Format

Share Document