scholarly journals Side-Chain Liquid Crystal Co-Polymers for Angular Photochromic Anti-Counterfeiting Powder and Fiber

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 128
Author(s):  
Yanzi Gao ◽  
Ke Feng ◽  
Jin Zhang ◽  
Lanying Zhang
Keyword(s):  
Liquid Crystal ◽  
Cholesteric Liquid Crystal ◽  
Side Chain ◽  
Scanning Calorimetry ◽  
Selective Reflection ◽  
Cost Performance ◽  
Self Assembling ◽  
Planar Texture ◽  
Potential Applications ◽  
Photochromic Materials

Anti-counterfeiting technologies with the features of easy distinguishability, high cost performance, and good processability are needed to meet the demands of a market during the consumption upgrading moment. A series of side-chain liquid crystal co-polymers (SCLCPs) are designed, synthesized, and blended, and the preparation of a series of angular photochromic materials that have different center reflection wavelengths in the visible and near infra-red region is reported in this article. Differential scanning calorimetry and polarized optical microscopy were utilized to characterize the phase transition behaviors and self-assembling structures of the SCLCPs. The selective reflection properties were characterized with a UV/VIS/IR spectrum study and further verified by scanning electron microscopy. The results showed that the SCLCPs had the desired reflection wavelengths and thermal stability. The SCLCPs could easily form a planar texture of cholesteric liquid crystal and, depending on the good processability, anti-counterfeiting powders and fibers with angular photochromic features were prepared and characterized to prove the potential applications of the SCLCPs in anti-counterfeiting labels.

Synthesis and Characterization of a Cholesteric Liquid Crystal Cholesteryl Nonanoate

2010 ◽  
Vol 428-429 ◽  
pp. 94-97 ◽  
Author(s):  
Yuan Ming Huang ◽  
Ye Tang Guo ◽  
Qing Lan Ma ◽  
Wei Wei Liu
Keyword(s):  
Liquid Crystal ◽  
Cholesteric Liquid Crystal ◽  
Synthesis And Characterization ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
Selective Reflection ◽  
Cholesteric Phase ◽  
Polarized Optical Microscopy ◽  
Clearing Point

A cholesteric liquid crystal cholesteryl nonanoate was synthesized and then characterized by means of differential scanning calorimetry and polarized optical microscopy. As temperature decreased from its clearing point, cholesteric phase was formed for cholesteryl nonanoate and accompanied by continuous evolution of colors in the focal conic textures. Furthermore, beautiful spherulite crystals were observed to grow out of the cholesteric phase as the crystallization continued. The evolution of the colors in recorded textures was contributed to temperature-dependent selective reflection of the liquid crystal.

scholarly journals Reflectivity of Cholesteric Liquid Crystals with an Anisotropic Defect Layer Inside

Photonics ◽  
2020 ◽  
Vol 7 (3) ◽  
pp. 58
Author(s):  
Dariusz Grzelczyk ◽  
Jan Awrejcewicz
Keyword(s):  
Liquid Crystal ◽  
Electric Field ◽  
Cholesteric Liquid Crystal ◽  
Defect Layer ◽  
Selective Reflection ◽  
System A ◽  
Potential Applications ◽  
Simulation Results ◽  
Optical Phenomena ◽  
Electrical Conductors

In this study, first, we numerically investigated the reflectivity of a cholesteric liquid crystal with an anisotropic defect layer inside. To model optical phenomena in the examined system, a 4 × 4 matrix method was employed. The tests were carried out for different thicknesses of the whole system, different thicknesses of the defect layer, as well as different defect layer locations inside the cell. Next, a cholesteric liquid crystal comprising a defect layer and held between two parallel electrical conductors was also considered. In this case, the optical properties of the system could also be adjusted by an external applied electric field. Some interesting simulation results of the reflection coefficient (i.e., the fraction of electromagnetic energy reflected) were obtained, illustrated, and discussed. The simulation results showed a significant influence of both the defect and the external electric field on the selective reflection phenomenon, and the possibility of controlling the shape of the reflection spectrum. Finally, some potential applications of the analyzed optical system were discussed.

scholarly journals Front Cover: Chiral, Thermally Irreversible and Quasi‐Stealth Photochromic Dopant to Control Selective Reflection Wavelength of Cholesteric Liquid Crystal (ChemPhysChem 13/2020)

ChemPhysChem ◽  
2020 ◽  
Vol 21 (13) ◽  
pp. 1340-1340
Author(s):  
Yoshihisa Kurosaki ◽  
Toshiya Sagisaka ◽  
Tomoo Matsushima ◽  
Takashi Ubukata ◽  
Yasushi Yokoyama
Keyword(s):  
Liquid Crystal ◽  
Cholesteric Liquid Crystal ◽  
Selective Reflection ◽  
Front Cover

scholarly journals Chiral, Thermally Irreversible and Quasi‐Stealth Photochromic Dopant to Control Selective Reflection Wavelength of Cholesteric Liquid Crystal

ChemPhysChem ◽  
2020 ◽  
Vol 21 (13) ◽  
pp. 1343-1344
Author(s):  
Yoshihisa Kurosaki ◽  
Toshiya Sagisaka ◽  
Tomoo Matsushima ◽  
Takashi Ubukata ◽  
Yasushi Yokoyama
Keyword(s):  
Liquid Crystal ◽  
Cholesteric Liquid Crystal ◽  
Selective Reflection

scholarly journals Self-Assembling Behavior of Smart Nanocomposite System: Ferroelectric Liquid Crystal Confined by Stretched Porous Polyethylene Film

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1498
Author(s):  
Alexej Bubnov ◽  
Alexey Bobrovsky ◽  
Ivan Rychetský ◽  
Ladislav Fekete ◽  
Věra Hamplová
Keyword(s):  
Liquid Crystal ◽  
Dielectric Spectroscopy ◽  
Helical Structure ◽  
Dielectric Behavior ◽  
Ferroelectric Liquid Crystal ◽  
Porous Polyethylene ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Self Assembling ◽  
Nanocomposite System

The control and prediction of soft systems exhibiting self-organization behavior can be realized by different means but still remains a highlighted task. Novel advanced nanocomposite system has been designed by filling of a stretched porous polyethylene (PE) film with pore dimensions of hundreds of nanometers by chiral ferroelectric liquid crystalline (LC) compound possessing polar self-assembling behavior. Lactic acid derivative exhibiting the paraelectric orthogonal smectic A* and the ferroelectric tilted smectic C* phases over a broad temperature range is used as a self-assembling compound. The morphology of nanocomposite film has been checked by Atomic Force Microscopy (AFM). The designed nanocomposite has been studied by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), small and wide-angle X-ray scattering and broadband dielectric spectroscopy. The effect of a porous PE confinement on self-assembling, structural, and dielectric behavior of the chiral LC compound has been established and discussed. While the mesomorphic and structural properties of the nanocomposite are found not to be much influenced in comparison to that of a pure LC compound, the polar properties have been toughly suppressed by the specific confinement. Nevertheless, the electro-optic switching was clearly observed under applied electric field of low frequency (210 V, 19 Hz). The dielectric spectroscopy and X-ray results reveal that the helical structure of the ferroelectric liquid crystal inside the PE matrix is completely unwound, and the molecules are aligned along stretching direction. Obtained results demonstrate possibilities of using stretched porous polyolefins as promising matrices for the design of new nanocomposites.

Synthesis and Phase Behavior of Chiral Liquid Crystal Elastomers Containing Cholesteryl Group

2012 ◽  
Vol 554-556 ◽  
pp. 807-810 ◽  
Author(s):  
Ying Gang Jia ◽  
Kun Ming Song ◽  
Bao Yan Zhang
Keyword(s):  
Phase Behavior ◽  
Liquid Crystalline ◽  
Crosslinking Agent ◽  
Side Chain ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Selective Reflection ◽  
Cholesteric Phase ◽  
Liquid Crystal Elastomers ◽  
Cholesteric Liquid Crystalline

The synthesis of new side chain cholesteric liquid crystalline elastomers (ChLCEs) containing the cholesteric monomer M and the flexible non-mesogenic crosslinking agent C, is described. The selective reflection of light for M was characterized with UV/Visible/NIR. The phase behavior and mesomorphism were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction (XRD). The effect of the content of crosslinking units on the phase behavior and mesomorphism of elastomers P1– P8is discussed. The ChLCEs exhibit elasticity, reversible phase transitions, and cholesteric Grandjean texture. The experimental results demonstrate that the glass transition temperature and isotropic temperature of ChLCEs decrease with increasing the content of crosslinking unit, but the cholesteric phase is not disturbed.

Effects of Anthraquinone Dye Aggregation on Selective Reflection Spectra of Cholesteric Liquid Crystal

2008 ◽  
Vol 496 (1) ◽  
pp. 202-211 ◽  
Author(s):  
V. M. Pergamenshchik ◽  
R. M. Vasyuta ◽  
O. P. Boiko ◽  
V. G. Nazarenko ◽  
L. N. Zavora ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Cholesteric Liquid Crystal ◽  
Reflection Spectra ◽  
Selective Reflection ◽  
Anthraquinone Dye ◽  
Dye Aggregation

Optical properties of side-chain liquid crystal copolymers of monosubstituted cholesteryl itaconate and a non-chiral mesogen

1995 ◽  
Vol 73 (11) ◽  
pp. 1811-1817 ◽  
Author(s):  
J.M.G. Cowie ◽  
H.W. Hunter
Keyword(s):  
Itaconic Acid ◽  
Liquid Crystalline ◽  
Glassy State ◽  
Side Chain ◽  
Ultraviolet Region ◽  
Scanning Calorimetry ◽  
Selective Reflection ◽  
Cholesteric Phase ◽  
Crystalline Polymers ◽  
Derivatives Of

New mono- and disubstituted cholesteryl derivatives of itaconic acid have been prepared and their thermotropic liquid crystalline behaviour examined. The monosubstituted derivative has been homopolymerized, and also copolymerized with a non-chiral mesogen 4-cyanophenyl-4′-(6-acryloyl oxyhexyloxy) benzoate. Examination of the series of copolymers prepared, using differential scanning calorimetry and hot-stage polarizing microscopy, showed that when the content of the cholesteryl itaconate was high, both a smectic-A phase (SA) and a cholesteric phase (N*) were present. It was found that the SA phase could be eliminated by lowering the content of the cholesteryl itaconate in the copolymers, giving samples that displayed only the N* phase over a much wider temperature range. The samples in the N* phase also exhibited selective reflection of visible light that changed from short to long wavelengths as the samples were cooled from the isotropic melt. These colours can be locked into the glassy state of the polymer by quenching below the glass transition temperature, but only if the SA phase is absent. It was also noted that at high contents of the cholesteryl itaconate the selective reflection appears to occur in the ultraviolet region. Keywords: itaconic acid, copolymers, liquid crystalline polymers, cholesteric phases, selective reflection.

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