New Liquid Crystalline Material with an Azo Group in the Molecular Core

2011 ◽  
Vol 130-134 ◽  
pp. 1520-1522
Author(s):  
Si Chen ◽  
Si Pei Li ◽  
Xu Wang
Keyword(s):  
Nematic Phase ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Crystalline Material ◽  
Scanning Calorimetry ◽  
Chemical Structures ◽  
Phase Structures ◽  
Molecular Core ◽  
Azo Group ◽  
Liquid Crystalline Material

A new kind of liquid crystalline material with an azo group in the molecular core was synthesized successfully. The chemical structures of the compounds were confirmed by mass spectrometry and 1H NMR. Their phase structures and transitions were investigated by differential scanning calorimetry. And the liquid crystalline behaviors were researched with polarized light microscopy experiments. The experimental results suggested that the compounds with a azo group in the molecular core can develop into a well-defined nematic phase.

scholarly journals ‘Quasi-Tricritical’ and Glassy Dielectric Properties of a Nematic Liquid Crystalline Material

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 297 ◽  
Author(s):  
Aleksandra Drozd-Rzoska
Keyword(s):  
Relaxation Time ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Strong Electric Field ◽  
Low Frequency ◽  
Ionic Species ◽  
Crystalline Material ◽  
Isotropic Liquid ◽  
The Impact ◽  
Liquid Crystalline Material

Results of dielectric studies in the nematic and isotropic liquid phases of pentylcyanobiphenyl (5CB), a model rod-like liquid crystalline material, are shown. They are based on the discussion of the evolution of dielectric constant ( ε ), its changes under the strong electric field (nonlinear dielectric effect, NDE), and finally, the primary relaxation time. It is shown that changes in ε T and NDE are entirely dominated by the impact of pretransitional fluctuations (pre-nematic and pre-isotropic, respectively) which are associated with the weakly discontinuous character of the isotropic–nematic phase transition. This influence also extends for the low-frequency, ionic species dominated, region. Notable, that the derivative-based and distortions sensitive analysis revealed the tricritical nature of the I-N transition. Although the glass transition in 5CB occurs in the deeply supercooled state at T g ≈ − 68 ° C , the dynamics (changes of the primary relaxation time) follow a previtreous pattern both in the isotropic and in the nematic phase. Finally, the discussion of the ’molecular’ vs. ‘quasi-critical’ characterizations of the isotropic and nematic phases is presented. It shows the evident prevalence of the ‘quasi-critical-picture’, which offers the consistent temperature parameterization in the total tested temperature range.

New Liquid Crystalline Material Exhibiting a Reentrant Nematic Phase

1983 ◽  
Vol 100 (3-4) ◽  
pp. 299-305 ◽  
Author(s):  
Shunsuke Takenaka ◽  
Hideyuki Nakai ◽  
Shigekazu Kusabayashi
Keyword(s):  
Nematic Phase ◽  
Liquid Crystalline ◽  
Crystalline Material ◽  
Liquid Crystalline Material

Thermotropic behavior of sodium cholesteryl carbonate

2009 ◽  
Vol 24 (1) ◽  
pp. 156-163 ◽  
Author(s):  
Rabkwan Chuealee ◽  
Timothy S. Wiedmann ◽  
Teerapol Srichana
Keyword(s):  
Phase Behavior ◽  
Chemical Structure ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Wave Number ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
C Nmr

Sodium cholesteryl carbonate ester (SCC) was synthesized, and its phase behavior was studied. The chemical structure was assessed by solid-state infrared spectroscopy based on vibration analysis. The wave number at 1705 and 1276 cm−1 corresponds to a carbonyl carbonate and O–C–O stretching of SCC, respectively. Molecular structure of SCC was further investigated with 1H and 13C NMR spectroscopy. The chemical shift, for the carbonyl carbonate resonance appeared at 155.5 ppm. A molecular mass of SCC was at m/z of 452. Differential scanning calorimetry (DSC), video-enhanced microscopy (VEM) together with polarized light microscopy, and small-angle x-ray scattering (SAXS) were used to characterize the phase behavior as a function of temperature of SCC. Liquid crystalline phase was formed with SCC. Based on the thermal properties and x-ray diffraction, it appears that SCC forms a structure analogous to the type II monolayer structure observed with cholesterol esters.

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.

Phase Transition Behavior of Main Chain Nematic Liquid-Crystalline Polymers Based on 2-methyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone and 2-tert-butyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone

2012 ◽  
Vol 1403 ◽  
Author(s):  
Christain Melchert ◽  
M. Behl ◽  
A. Lendlein
Keyword(s):  
Phase Transition ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Phase Transition Behavior ◽  
Scanning Calorimetry ◽  
Thermal Stabilities ◽  
Crystalline Polymers ◽  
Transition Behavior ◽  
X Ray Scattering

ABSTRACTThe control of phase transition behavior in liquid crystalline polymers could enable potential application in the field of actuators and sensors by enabling a higher actuator performance of liquid crystalline elastomers (LCE). In this context the phase transition behavior of siloxane based liquid crystalline copolymers synthesized from 1,1,3,3-tetramethyldisiloxane, 2-methyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone (M-MeHq), and 2-tert-butyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone (M-tBHq) was explored. The selected monomers provided different thermal stabilities of the nematic phase, while the non-flexible siloxane spacer suppressed a smectic phase. The mesogenic properties were studied by means of differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and wide angle X-ray scattering (WAXS). With increasing fraction of M-MeHq the nematic phase of the copolymer was stabilized and a tailoring of relatively low TNI was achieved.

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