scholarly journals Spatially resolved mapping of phase transitions in liquid-crystalline materials by X-ray birefringence imaging

2019 ◽  
Vol 10 (10) ◽  
pp. 3005-3011 ◽  
Author(s):  
Yating Zhou ◽  
Rhian Patterson ◽  
Benjamin A. Palmer ◽  
Gregory R. Edwards-Gau ◽  
Benson M. Kariuki ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Liquid Crystalline ◽  
Crystalline Materials ◽  
X Ray ◽  
Spatially Resolved ◽  
Liquid Crystalline Materials ◽  
Sensitive Method

X-ray Birefringence Imaging is shown to be a sensitive method for spatially resolved mapping of molecular orientations in liquid-crystalline materials.

scholarly journals The Role of Substitution in the Apex Position of the Bent-Core on Mesomorphic Properties of New Series of Liquid Crystalline Materials

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 735 ◽  
Author(s):  
Helena Skopalová ◽  
Petr Špaček ◽  
Václav Kozmík ◽  
Jiří Svoboda ◽  
Vladimíra Novotná ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Structural Parameters ◽  
Phase Identification ◽  
Crystalline Materials ◽  
X Ray ◽  
Alkyl Chains ◽  
Calorimetric Measurements ◽  
Liquid Crystalline Materials ◽  
Mesomorphic Properties

We present the synthesis and mesomorphic properties of the new series of bent-core liquid crystals based on 3-hydroxybenzoic acid bearing a lateral substituent in the apex position. Four different substituents of various sizes and electronic properties have been used. We have found that only compounds substituted with fluorine are mesogenic and exhibit one mesophase, whose type differs when prolonging the terminal alkyl chain. For homologues with shorter alkyl chains (octyl, decyl), a columnar B1-type of a mesophase was observed, while materials with longer terminal chains (dodecyl, tetradecyl) exhibited a switchable lamellar SmCAPA phase. Calorimetric measurements, texture observations under a polarizing microscope were performed and electro-optical properties studied. Additionally, dielectric measurements were realized to characterize the molecular dynamics in the SmCAPA phase. All mesogenic compounds were further studied by X-ray measurements to confirm phase identification and obtain more information about their structural parameters.

scholarly journals Mesomorphism behaviour and photoluminescent properties of new asymmetrical 1,2-di(4-alkoxybenzylidene)hydrazines

2019 ◽  
Vol 43 (1-2) ◽  
pp. 67-77 ◽  
Author(s):  
Adil A Awad ◽  
Al-Ameen Bariz OmarAli ◽  
Ahmed Jasim M Al-Karawi ◽  
Zyad Hussein J Al-Qaisi ◽  
Samer Ghanim Majeed
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Luminescent Properties ◽  
Scanning Calorimetry ◽  
Crystalline Materials ◽  
X Ray ◽  
Step Procedure ◽  
Liquid Crystalline Materials

{1-[4-( n-Alkoxy)]-2-(4’-decyloxy)benzylidene}hydrazines ( n-alkoxy = O(CH2) nH, n = 1–9, 12, 16 or 18), an asymmetrical series of 1,2-disubstituted hydrazines, were prepared in a simple two-step procedure as a part of our continuing work in evaluating hydrophobic azine compounds as photoluminescent liquid crystalline materials. The compounds were characterized spectroscopically and their liquid crystalline behaviour and luminescent properties were evaluated using polarized light optical microscopy, differential scanning calorimetry and X-ray powder diffraction techniques. The studies revealed that all of these compounds are liquid crystalline materials exhibiting photoluminescent properties in the crystalline and liquid crystal states.

Lamellar Liquid Crystalline Materials Modulated by 1-Ethyl-3-Methylimidazolium Hexafluorophosphate

2014 ◽  
Vol 1025-1026 ◽  
pp. 760-764
Author(s):  
Guo Dong Zhang ◽  
Wen Chang Zhuang ◽  
Jing Tian ◽  
Chang Cheng Zhang ◽  
Long Li Zhang ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Lamellar Phase ◽  
Tetraethylene Glycol ◽  
Imidazolium Salt ◽  
Polarized Optical Microscopy ◽  
Crystalline Materials ◽  
X Ray ◽  
X Ray Scattering ◽  
Lauryl Ether ◽  
Liquid Crystalline Materials

Liquid crystal was formed in a ternary system of tetraethylene glycol lauryl ether, water and 1-ethyl-3-methylimidazolium hexafluorophosphate. Its structure was identified by polarized optical microscopy and small-angle X-ray scattering techniques. Compared to that in the binary system, lamellar phase was retained with the addition of a small amount of imidazolium salt. Molecules of 1-ethyl-3-methylimidazolium hexafluorophosphate were considered to be solubilized in the polar domain of the ordered assemblies. Results on their influence on the lamellar phase enlighten the use of imidazolium salts to modulate liquid crystalline materials and other assemblies.

Thermal analysis and X-ray studies of chiral ferroelectric liquid crystalline materials and their binary mixtures

2005 ◽  
Vol 82 (2) ◽  
pp. 519-523 ◽  
Author(s):  
Dusanka Ž. Obadović ◽  
Anikó Vajda ◽  
Maya Garić ◽  
A. Bubnov ◽  
Vera Hamplová ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Binary Mixtures ◽  
Liquid Crystalline ◽  
Crystalline Materials ◽  
X Ray ◽  
Liquid Crystalline Materials

Multipodal Liquid-Crystalline Materials based on Ferrocene Cores

2001 ◽  
Vol 709 ◽  
Author(s):  
T. Meyer ◽  
R. Elsäßer ◽  
K. J. Shepperson ◽  
D. Vos ◽  
B. Donnio ◽  
...  
Keyword(s):  
Crystalline Phase ◽  
Liquid Crystalline ◽  
Liquid Crystalline Phase ◽  
X Ray Diffraction ◽  
Crystalline Materials ◽  
X Ray ◽  
Liquid Crystalline Materials ◽  
Phase Properties

ABSTRACTThe synthesis of multipodes based on substituted ferrocene groups and the results of the investigations of the liquid-crystalline phase properties of these materials, determined by optical polarising microscopy DSC and X-ray diffraction studies as central cores is reported.

On resolving fine periodic microstructures in the optical microscope

1989 ◽  
Vol 47 ◽  
pp. 364-365
Author(s):  
W.S. Putnam ◽  
C. Viney
Keyword(s):  
Liquid Crystalline ◽  
Numerical Aperture ◽  
Polarized Light ◽  
Normal Incidence ◽  
Optical Microscope ◽  
Angle Of Incidence ◽  
Resolution Limit ◽  
Crystalline Materials ◽  
Periodic Microstructures ◽  
Liquid Crystalline Materials

Many sheared liquid crystalline materials (fibers, films and moldings) exhibit a fine banded microstructure when observed in the polarized light microscope. In some cases, for example Kevlar® fiber, the periodicity is close to the resolution limit of even the highest numerical aperture objectives. The periodic microstructure reflects a non-uniform alignment of the constituent molecules, and consequently is an indication that the mechanical properties will be less than optimal. Thus it is necessary to obtain quality micrographs for characterization, which in turn requires that fine detail should contribute significantly to image formation.It is textbook knowledge that the resolution achievable with a given microscope objective (numerical aperture NA) and a given wavelength of light (λ) increases as the angle of incidence of light at the specimen surface is increased. Stated in terms of the Abbe resolution criterion, resolution improves from λ/NA to λ/2NA with increasing departure from normal incidence.

Designing Chemically Selective Liquid Crystalline Materials that Respond to Oxidizing Gases

2021 ◽  
Author(s):  
Nanqi Bao ◽  
Jake Gold ◽  
Tibor Szilvasi ◽  
Huaizhe Yu ◽  
Robert Twieg ◽  
...  
Keyword(s):  
Computational Methods ◽  
First Principles ◽  
Liquid Crystalline ◽  
Soft Materials ◽  
Crystalline Materials ◽  
Liquid Crystalline Materials ◽  
Chemically Selective ◽  
Kinetics Of

Computational methods can provide first-principles insights into the thermochemistry and kinetics of reactions at interfaces, but this capability has not been widely leveraged to design soft materials that respond selectively...

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