Effect of cholesteric liquid crystalline elastomer with binaphthalene crosslinkings on thermal and optical properties of a liquid crystal that show smectic A-cholesteric phase transition

2012 ◽  
Vol 24 (2) ◽  
pp. 228-235 ◽  
Author(s):  
Xiaojuan Wu ◽  
Hui Cao ◽  
Renwei Guo ◽  
Kexuan Li ◽  
Feifei Wang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Optical Properties ◽  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Cholesteric Phase ◽  
Smectic A ◽  
Cholesteric Liquid Crystalline

Cholesteric liquid crystal glass platinum acetylides

2014 ◽  
Vol 1698 ◽  
Author(s):  
Thomas M. Cooper ◽  
Aaron R. Burke ◽  
Douglas M. Krein ◽  
Ronald F. Ziolo ◽  
Eduardo Arias ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Optical Materials ◽  
Liquid Crystalline ◽  
Room Temperature ◽  
Cholesteric Liquid Crystal ◽  
Isotropic Phase ◽  
Crystal Glass ◽  
Cholesteric Phase ◽  
Long Time ◽  
Cholesteric Liquid Crystalline

ABSTRACTTo prepare cholesteric liquid crystalline nonlinear optical materials with ability to be vitrified on cooling and form long time stability cholesteric glasses at room temperature, a series of platinum acetylide complexes modified with cholesterol has been synthesized. The materials synthesized have the formula trans-Pt(PR3)(cholesterol (3 or 4)-ethynyl benzoate)(1-ethynyl-4-X-benzene), where R = Et, Bu or Oct and X = H, F, OCH3 and CN. A cholesteric liquid crystal phase was observed in the complexes R = Et, and X = F, OCH3 and CN but not in any of the other complexes. When X = CN, a cholesteric glass was observed at room temperature which remained stable up to 130 °C, then converted to a mixed crystalline/cholesteric phase and completely melted to an isotropic phase at 230 °C. When X = F or OCH3 the complexes were crystalline at room temperature with conversion to the cholesteric phase upon heating to 190 and 230 °C, respectively. In the series X = CN, OCH3 and F, the cholesteric pitch was determined to be 1.7, 3.4 and 9.0 µ, respectively.

Effects on thermo‐optical properties of the composition of a polymer‐stabilised liquid crystal with a smectic A–chiral nematic phase transition

2008 ◽  
Vol 35 (9) ◽  
pp. 1151-1160 ◽  
Author(s):  
Guohui Pan ◽  
Lilong Yu ◽  
Hongbin Zhang ◽  
Jinbao Guo ◽  
Renwei Guo ◽  
...  
Keyword(s):  
Phase Transition ◽  
Optical Properties ◽  
Liquid Crystal ◽  
Nematic Phase ◽  
Smectic A ◽  
Chiral Nematic

First observation of a smectic A–cholesteric phase transition in a thermotropic liquid crystal consisting of a rigid-rod helical polysilane

2004 ◽  
Vol 31 (2) ◽  
pp. 279-283 ◽  
Author(s):  
Kento Okoshi ◽  
Anubhav Saxena ◽  
Masanobu Naito ◽  
Goro Suzaki ◽  
Masatoshi Tokita ◽  
...  
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Cholesteric Phase ◽  
Thermotropic Liquid Crystal ◽  
Smectic A ◽  
Rigid Rod

scholarly journals Hydrophobic gold nanoparticles via silane conjugation: chemically and thermally robust nanoparticles as dopants for nematic liquid crystals

2013 ◽  
Vol 371 (1988) ◽  
pp. 20120256 ◽  
Author(s):  
Javad Mirzaei ◽  
Martin Urbanski ◽  
Heinz-S. Kitzerow ◽  
Torsten Hegmann
Keyword(s):  
Phase Transition ◽  
Gold Nanoparticles ◽  
Optical Properties ◽  
Liquid Crystal ◽  
Threshold Voltage ◽  
Nematic Phase ◽  
Dielectric Anisotropy ◽  
Smectic A ◽  
Gold Nps ◽  
First Time

We examine for the first time how chemically and thermally stable gold nanoparticles (NPs), prepared by a silane conjugation approach, affect both the thermal and the electro-optical properties of a nematic liquid crystal (LC), when doped at concentrations ranging from 0.25 to 7.5 wt%. We find that the octadecylsilane-conjugated gold NPs stabilize both the enantiotropic nematic and the monotropic smectic-A phases of the LC host with a maximum stabilization of 2 ° C for the nematic and 3.5 ° C for the smectic-A phases for the mixture containing 1 wt% of the silanized particles. The same mixture shows the lowest values for the Fréedericksz transition threshold voltage and the highest value for the dielectric anisotropy. Generally, all NP-containing mixtures, except mixtures with NP concentrations exceeding 5 wt%, reduce the threshold voltage, increase the dielectric anisotropy and reduce both rise and decay time; the latter particularly at temperatures at least 10 ° C below the isotropic–nematic phase transition on cooling.

Characterization of some mesogenic alkyl 1-thioglycosides

2002 ◽  
Vol 80 (8) ◽  
pp. 1162-1165 ◽  
Author(s):  
B Henrissat ◽  
G K Hamer ◽  
M G Taylor ◽  
R H Marchessault
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Solid State ◽  
Solid State Nmr ◽  
Liquid Crystalline ◽  
Liquid Crystal Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Liquid Crystalline Phases

A series of dodecyl 1-thio-β-D-glycosides has been synthesized and characterized (DSC, NMR, CP MAS, X-ray diffraction) as possible new marking materials with liquid-crystalline properties. These compounds undergo solid to liquid crystal phase transitions at various temperatures, which depend on the nature of the carbohydrate part of the structure. Their liquid-crystalline phases show extreme shear thinning behaviour.Key words: liquid crystal, powder X-ray diffraction, phase transition, thioglycoside, solid-state NMR, marking material

scholarly journals Optical Microscopy Observations and Construction of Dupin Cyclides at the Isotropic/Smectic A Phase Transition

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4539
Author(s):  
Mikhael Halaby Macary ◽  
Gauthier Damême ◽  
Antoine Gibek ◽  
Valentin Dubuffet ◽  
Benoît Dupuy ◽  
...  
Keyword(s):  
Phase Transition ◽  
Numerical Simulation ◽  
Liquid Crystal ◽  
Optical Microscopy ◽  
Smectic A ◽  
Polarized Microscopy ◽  
Smectic A Phase ◽  
Dupin Cyclides

In this work, we are interested in the nucleation of bâtonnets at the Isotropic/Smectic A phase transition of 10CB liquid crystal. Very often, these bâtonnets are decorated with a large number of focal conics. We present here an example of a bâtonnet obtained by optical crossed polarized microscopy in a frequently observed particular area of the sample. This bâtonnet presents bulges and one of them consists of a tessellation of ellipses. These ellipses are two by two tangent, one to each other, and their confocal hyperbolas merge at the apex of the bâtonnet. We propose a numerical simulation with Python software to reproduce this tiling of ellipses as well as the shape of the smectic layers taking the well-known shape of Dupin cyclides within this particular bâtonnet area.

scholarly journals Smectic A: cholesteric phase transition investigated by small angle X-ray diffraction and viscosity measurements

2002 ◽  
Vol 32 (2b) ◽  
pp. 495-500 ◽  
Author(s):  
E. L. Duarte ◽  
R. Itri ◽  
A. R. Sampaio ◽  
M. Simões ◽  
A. J. Palangana
Keyword(s):  
Phase Transition ◽  
Small Angle ◽  
X Ray Diffraction ◽  
Cholesteric Phase ◽  
X Ray ◽  
Viscosity Measurements ◽  
Smectic A
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