Automated determination of n-cyanobiphenyl and n-cyanobiphenyl binary mixtures elastic constants in the nematic phase from molecular simulation

2020 ◽  
Vol 5 (6) ◽  
pp. 1131-1136
Author(s):  
Jiale Shi ◽  
Hythem Sidky ◽  
Jonathan K. Whitmer
Keyword(s):  
Liquid Crystals ◽  
Molecular Simulation ◽  
Elastic Properties ◽  
Binary Mixtures ◽  
Elastic Constants ◽  
Nematic Phase ◽  
New Techniques ◽  
New Applications ◽  
Automated Determination

This work explores new techniques in molecular simulation which can be used to precisely determine and engineer elastic properties of liquid crystals for new applications.

scholarly journals Correction: Automated determination of n-cyanobiphenyl and n-cyanobiphenyl binary mixtures elastic constants in the nematic phase from molecular simulation

2020 ◽  
Vol 5 (8) ◽  
pp. 1437-1437
Author(s):  
Jiale Shi ◽  
Hythem Sidky ◽  
Jonathan K. Whitmer
Keyword(s):  
Molecular Simulation ◽  
Binary Mixtures ◽  
Elastic Constants ◽  
Nematic Phase ◽  
Automated Determination

Correction for ‘Automated determination of n-cyanobiphenyl and n-cyanobiphenyl binary mixtures elastic constants in the nematic phase from molecular simulation’ by Jiale Shi et al., Mol. Syst. Des. Eng., 2020, 5, 1131–1136, DOI: 10.1039/C9ME00065H.

scholarly journals Extremely small twist elastic constants in lyotropic nematic liquid crystals

2020 ◽  
Vol 117 (44) ◽  
pp. 27238-27244 ◽  
Author(s):  
Clarissa F. Dietrich ◽  
Peter J. Collings ◽  
Thomas Sottmann ◽  
Per Rudquist ◽  
Frank Giesselmann
Keyword(s):  
Liquid Crystals ◽  
Elastic Constant ◽  
Elastic Constants ◽  
Nematic Phase ◽  
Elastic Moduli ◽  
Building Blocks ◽  
Lyotropic Liquid Crystals ◽  
Order Of Magnitude ◽  
Typical Range ◽  
Special Case

Recent measurements of the elastic constants in lyotropic chromonic liquid crystals (LCLCs) have revealed an anomalously small twist elastic constant compared to the splay and bend constants. Interestingly, measurements of the elastic constants in the micellar lyotropic liquid crystals (LLCs) that are formed by surfactants, by far the most ubiquitous and studied class of LLCs, are extremely rare and report only the ratios of elastic constants and do not include the twist elastic constant. By means of light scattering, this study presents absolute values of the elastic constants and their corresponding viscosities for the nematic phase of a standard LLC composed of disk-shaped micelles. Very different elastic moduli are found. While the splay elastic constant is in the typical range of 1.5 pN as is true in general for thermotropic nematics, the twist elastic constant is found to be one order of magnitude smaller (0.30 pN) and almost two orders of magnitude smaller than the bend elastic constant (21 pN). These results demonstrate that a small twist elastic constant is not restricted to the special case of LCLCs, but is true for LLCs in general. The reason for this extremely small twist elastic constant very likely originates with the flexibility of the assemblies that are the building blocks of both micellar and chromonic lyotropic liquid crystals.

On: “RECENT TECHNIQUES FOR DETERMINATION OF IN SITU ELASTIC PROPERTIES AND MEASUREMENT OF MOTION AMPLIFICATION IN LAYERED MEDIA,” BY R.J. SWAIN (GEOPHYSICS, APRIL, 1962, PP. 237–241).

Geophysics ◽  
1963 ◽  
Vol 28 (1) ◽  
pp. 112-112 ◽  
Author(s):  
Harry R. Nicholls
Keyword(s):  
Elastic Properties ◽  
Elastic Constants ◽  
Design Problem ◽  
Critical Angle ◽  
Specific Design ◽  
Design Problems ◽  
Relative Value ◽  
Angle Method

Although I am in general agreement with Mr. Swain’s paper, there are several pitfalls inherent in the use of dynamic elastic constants which should not be ignored. The strength of materials and the elastic properties both undoubtedly depend on the rate of loading and/or the stress levels involved. It does not seem appropriate, therefore, to use dynamic in situ elastic properties for static design problems. The specific design problem at hand should determine the relative value placed on the use of static or dynamic elastic constants. The dynamic in situ values are generally more reliable than those obtained in the laboratory as indicated by Mr. Swain, although continued development of the laboratory pulse and critical‐angle method shows promise of improving the reliability of laboratory values.

Notizen: Bestimmung des Helixdrehsinnes cholesterischer Phasen mit der Grandjean-Cano-Methode / Determination of the Helical Sense of Cholesteric Liquid Crystals Using the Grandjean-Cano Method

1977 ◽  
Vol 32 (8) ◽  
pp. 899-902 ◽  
Author(s):  
G. Heppke ◽  
F. Oestreicher
Keyword(s):  
Molecular Structure ◽  
Liquid Crystals ◽  
Nematic Phase ◽  
Ring System ◽  
Cholesteric Liquid Crystals ◽  
Cholesteric Phase ◽  
Chiral Compounds ◽  
Helix Pitch

Abstract A simple way of determining the helix screw sense of a cholesteric phase using the Grandjean-Cano method is described. The helix pitch as well as its sense is investigated for ten cholesteric phases, induced by mesogenic chiral com­pounds in the nematic isomere mixture of 4-methoxy-4′-n-butylazoxybenzene (Nematic Phase 4, Merck). For the chiral compounds with nematic-like molecular structure it is found that the screw sense alternates with the number of bonds between the chiral centre and the ring system.

RECENT TECHNIQUES FOR DETERMINATION OF “IN‐SITU” ELASTIC PROPERTIES AND MEASUREMENT OF MOTION AMPLIFICATION IN LAYERED MEDIA

Geophysics ◽  
1962 ◽  
Vol 27 (2) ◽  
pp. 237-241 ◽  
Author(s):  
R. J. Swain
Keyword(s):  
Engineering Design ◽  
Elastic Properties ◽  
Elastic Constants ◽  
Layered Media ◽  
Dynamic Loads ◽  
Safety Factors

Determination of the elastic properties of earth materials by laboratory means is subject to sizable errors. These errors may be serious in spite of the large safety factors normally used in engineering design, particularly if the structure must withstand severe dynamic loads. Means of obtaining elastic constants “in‐situ” are described. Further, the phenomenon of displacement multiplication between the underlying competent rock and overlying alluvium or fill is reviewed and the first instrumentation system designed specifically to measure this relationship for engineering purposes is described.

scholarly journals Determination of the high temperature elastic properties and diffraction elastic constants of Ni-base superalloys

2016 ◽  
Vol 89 ◽  
pp. 856-863 ◽  
Author(s):  
P.E. Aba-Perea ◽  
T. Pirling ◽  
P.J. Withers ◽  
J. Kelleher ◽  
S. Kabra ◽  
...  
Keyword(s):  
High Temperature ◽  
Elastic Properties ◽  
Elastic Constants

Numerical investigation of influence of ionic space charge and flexoelectric polarization on measurements of elastic constants in nematic liquid crystals

2009 ◽  
Vol 17 (2) ◽  
Author(s):  
M. Buczkowska ◽  
G. Derfel ◽  
M. Konowalski
Keyword(s):  
Magnetic Field ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
External Magnetic Field ◽  
Space Charge ◽  
Elastic Constants ◽  
High Concentration ◽  
Light Passing ◽  
The Magnetic Field

AbstractDeformations of nematic layers caused by magnetic field allow determination of the elastic constants of liquid crystal. In this paper, we simulated numerically the deformations of planar and homeotropic nematic layers. The flexoelectric properties of the nematic and presence of ions were taken into account. Our aim was to show the influence of flexoelectricity on the results of the real measurement of the elastic constants k33 and k11. In these simulations, we calculated the optical phase difference ΔΦ between the ordinary and extraordinary rays of light passing through the layer placed between crossed polarizers as a function of the magnetic field induction B. One of the elastic constants can be calculated from the magnetic field threshold for deformation. The ratio k33/k11 can be found by means of fitting theoretical ΔΦ(B) dependence to the experimental results. The calculations reveal that the flexoelectric properties influence the deformations induced by the external magnetic field. In the case of highly pure samples, this may lead to false results of measurement of the elastic constants ratio k33/k11. This influence can be reduced if the nematic material contains ions of sufficiently high concentration. These results show that the flexoelectric properties may play an important role, especially in well purified samples.

The Determination of the Elastic Constants of Nematic Liquid Crystals

1976 ◽  
Vol 37 (1) ◽  
pp. 269-280 ◽  
Author(s):  
W. H. De Jeu ◽  
W. A. P. Claassen ◽  
A. M. J. Spruijt
Keyword(s):  
Liquid Crystals ◽  
Elastic Constants ◽  
Nematic Liquid Crystals
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