TEMPERATURE DEPENDENCE OF THE PITCH IN CHOLESTERIC LIQUID CRYSTALS : A MOLECULAR STATISTICAL THEORY

1979 ◽  
Vol 40 (C3) ◽  
pp. C3-158-C3-163 ◽  
Author(s):  
W. J. A. GOOSSENS
Keyword(s):  
Statistical Theory ◽  
Liquid Crystals ◽  
Temperature Dependence ◽  
Cholesteric Liquid Crystals

scholarly journals Flexoelectric effect modelling

2008 ◽  
Vol 16 (4) ◽  
Author(s):  
A. Kapanowski
Keyword(s):  
Statistical Theory ◽  
Dipole Moment ◽  
Liquid Crystals ◽  
Temperature Dependence ◽  
Elastic Constants ◽  
Symmetry Axis ◽  
Order Parameters ◽  
Flexoelectric Effect ◽  
Calculate Temperature Dependence ◽  
Component Parallel

AbstractA statistical theory of dipole flexoelectric (FE) polarization in liquid crystals is used to calculate temperature dependence of order parameters, elastic constants and FE coefficients. Two systems with polar wedge-shaped and banana-shaped molecules are investigated. In both cases, the FE coefficients are proportional to the dipole moment component parallel to the molecule symmetry axis. It results from the symmetries of interactions and of the Mayer function. The origin of the FE effect and microscopic pictures of the distorted phases are discussed.

scholarly journals Statistical Theory of Elastic Constants of Cholesteric Liquid Crystals

2002 ◽  
Vol 57 (3-4) ◽  
pp. 105-118 ◽  
Author(s):  
Andrzej Kapanowski
Keyword(s):  
Statistical Theory ◽  
Liquid Crystals ◽  
Elastic Constants ◽  
Binary Systems ◽  
Cholesteric Liquid Crystals ◽  
Cholesteric Phase ◽  
Small Density ◽  
Nematic Phases ◽  
The Stability ◽  
The One

A statistical theory of cholesteric liquid crystals composed of short rigid biaxial molecules is presented. It is derived in the thermodynamic limit at a small density and a small twist. The uniaxial (biaxial) cholesteric phase is regarded as a distorted form of the uniaxial (biaxial) nematic phase. The chirality of the interactions and the implementation of the inversion to the rotation matrix elements are discussed in detail. General microscopic expressions for the elastic constants are derived. The expressions involve the one-particle distribution function and the potential energy of two-body short-range interactions. It is shown that the elastic constants determine the twist of the phase. The stability condition for the cholesteric and nematic phases is presented. The theory is used to study unary and binary systems. The temperature and concentration dependence of the order parameters, the elastic constants and the twist of the phase are obtained. The possibility of phase separation is not investigated.

scholarly journals A molecular‐statistical theory of the temperature‐dependent pitch in cholesteric liquid crystals

1976 ◽  
Vol 65 (10) ◽  
pp. 3935-3943 ◽  
Author(s):  
B. W. van der Meer ◽  
G. Vertogen ◽  
A. J. Dekker ◽  
J. G. J. Ypma
Keyword(s):  
Statistical Theory ◽  
Liquid Crystals ◽  
Cholesteric Liquid Crystals ◽  
Temperature Dependent

Relationship between molecular structures of uniquely designed C2-symmetric axially chiral dopants and their helical twisting properties in cholesteric liquid crystals

2019 ◽  
Vol 7 (8) ◽  
pp. 2225-2231 ◽  
Author(s):  
Daisuke Yoshizawa ◽  
Hiroki Higuchi ◽  
Yasushi Okumura ◽  
Hirotsugu Kikuchi
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Temperature Dependence ◽  
Molecular Structures ◽  
Positive Temperature ◽  
Cholesteric Liquid Crystals ◽  
Axially Chiral ◽  
Enhanced Properties ◽  
Chiral Dopants ◽  
Helical Twisting Power

9,9′-biphenanthrene-type chiral dopants were newly synthesized for the development of functional liquid crystal (LC) materials with enhanced properties. A cholesteric LC (CLC) with a chiral dopant showed positive temperature dependence of helical twisting power and a CLC with temperature independence was developed by mixing two types of chiral dopants.

scholarly journals Synthesis and Characterization of Novel Bio-Chiral Dopants Obtained from Bio-Betulin Produced by a Fermentation Process

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 785
Author(s):  
Veridiana G. Guimarães ◽  
Anastasiia Svanidze ◽  
Tianyi Guo ◽  
Pawan Nepal ◽  
Robert J. Twieg ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Natural Product ◽  
Fermentation Process ◽  
Synthesis And Characterization ◽  
Cholesteric Liquid Crystals ◽  
And Performance ◽  
Chiral Dopants

Cholesteric liquid crystals are frequently produced by the addition of chiral dopants to achiral nematic hosts. We report here the synthesis and performance of chiral dopants obtained from bio-betulin produced by a fermentation process. An important aspect of this work is to point out that the fermentation process used to obtain the starting materials is much easier and cheaper when carried out in large volumes than isolating it from the natural product. The performance of the dopants obtained from bio-betulin is indistinguishable from those obtained from commercially available synthetic betulin.

scholarly journals Augmented Lagrangian preconditioners for the Oseen–Frank model of nematic and cholesteric liquid crystals

2021 ◽  
Author(s):  
Jingmin Xia ◽  
Patrick E. Farrell ◽  
Florian Wechsung
Keyword(s):  
Liquid Crystals ◽  
Augmented Lagrangian ◽  
Augmented Lagrangian Method ◽  
Mass Matrix ◽  
Unit Length ◽  
Mesh Size ◽  
Schur Complement ◽  
Cholesteric Liquid Crystals ◽  
Multigrid Algorithm ◽  
The Cost

AbstractWe propose a robust and efficient augmented Lagrangian-type preconditioner for solving linearizations of the Oseen–Frank model arising in nematic and cholesteric liquid crystals. By applying the augmented Lagrangian method, the Schur complement of the director block can be better approximated by the weighted mass matrix of the Lagrange multiplier, at the cost of making the augmented director block harder to solve. In order to solve the augmented director block, we develop a robust multigrid algorithm which includes an additive Schwarz relaxation that captures a pointwise version of the kernel of the semi-definite term. Furthermore, we prove that the augmented Lagrangian term improves the discrete enforcement of the unit-length constraint. Numerical experiments verify the efficiency of the algorithm and its robustness with respect to problem-related parameters (Frank constants and cholesteric pitch) and the mesh size.

scholarly journals Pitch tuning induced by optical torque in heliconical cholesteric liquid crystals

2019 ◽  
Vol 1 (3) ◽  
Author(s):  
G. Nava ◽  
F. Ciciulla ◽  
O. S. Iadlovska ◽  
O. D. Lavrentovich ◽  
F. Simoni ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Cholesteric Liquid Crystals ◽  
Optical Torque
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