Local distortion energy and coarse-grained elasticity of the twist-bend nematic phase

Soft Matter ◽  
2016 ◽  
Vol 12 (2) ◽  
pp. 574-580 ◽  
Author(s):  
C. Meyer ◽  
I. Dozov
Keyword(s):  
Nematic Phase ◽  
Coarse Grained ◽  
Local Distortion ◽  
Coarse Grained Model ◽  
Smectic A ◽  
Smectic A Phase ◽  
Distortion Energy

We develop a coarse-grained model describing the macroscopic elasticity of the twist-bend nematic by analogy with the chiral smectic-A phase.

ANISOTROPY OF THE NEMATIC-SMECTIC A PHASE TRANSITION

1995 ◽  
Vol 09 (18n19) ◽  
pp. 2139-2155 ◽  
Author(s):  
BARBARA S. ANDERECK
Keyword(s):  
Phase Transition ◽  
Critical Behavior ◽  
Nematic Phase ◽  
Theoretical Work ◽  
Review Article ◽  
Superconducting Transition ◽  
Work Related ◽  
Smectic A ◽  
Smectic A Phase ◽  
Degree Of Anisotropy

Critical behavior at the transition from the nematic phase to the smectic A phase in liquid crystals has been of interest for over two decades. Discussions about the nature of the transition, its analogy to the superconducting transition, and the degree of anisotropy present in the critical exponents have been extensive during this time. This review article concentrates on the question of anisotropy at the nematic-smectic A transition. The experimental and theoretical work related to this question is summarized and compared. While progress has been made, there are many interesting questions related to this transition that remain for investigators to answer.

Structure and Thermal Behaviour of a Thermotropic Liquid Crystalline Polyimide (PI-LC)

1998 ◽  
Vol 10 (1) ◽  
pp. 147-153 ◽  
Author(s):  
M Tanaka ◽  
M Konda ◽  
M Miyamoto ◽  
Y Kimura ◽  
A Yamaguchi
Keyword(s):  
Phase Transition ◽  
Thermal Analysis ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Isotropic Phase ◽  
X Ray ◽  
Smectic A ◽  
Smectic C ◽  
Smectic A Phase

Anomalous solid structures formed by a thermotropic liquid crystalline polyimide (PI-LC) were investigated by thermal analysis, polarized light microscopy and x-ray analysis. It was revealed that PI-LC should undergo a phase transition from the crystalline to the isotropic phase through the smectic or nematic phase in the temperature range 277–300 °C. The PI-LC filament extruded at 280 °C, at which temperature the polymer was in liquid crystalline phase, was formed to have a structure similar to the smectic C phase, while that extruded and melt-drawn at 310 °C, at which temperature the polymer was in the isotropic phase, had a structure similar to the smectic A phase.

Dielectric Studies on Liquid Crystals under High Pressure: VI. Low Frequency Relaxation Process in the Nematic and Smectic A Phase of 4-n-Octyl-4'-Cyanobiphenyl (8 CB)

1994 ◽  
Vol 49 (4-5) ◽  
pp. 552-558 ◽  
Author(s):  
S. Urban ◽  
T. Brückert ◽  
A. Würflinger
Keyword(s):  
Nematic Phase ◽  
Liquid Crystalline ◽  
Activation Volume ◽  
Activation Enthalpy ◽  
Low Frequency ◽  
Smectic A ◽  
Liquid Crystalline Phases ◽  
Smectic A Phase ◽  
Frequency Relaxation ◽  
Increasing Temperature

Abstract Dielectric relaxation studies of 4-n-octyl-4'-cyanobiphenyl (8 CB) were performed in the pressure range 0.1 -120 MPa, the frequency range 1 kHz -13 MHz and the temperature range 295-331 K. The dielectric behaviour of 8C B in the nematic phase is similar to that of 5 CB, 6 CB and 7 CB. In particular, the activation enthalpy decreases with increasing pressure and the activation volume decreases with increasing temperature in the nematic phase. In the smectic A phase of 8 CB both these parameters are markedly lower and show opposite pressure and temperature dependencies. We tentatively interpret these effects as a result of breaking of the dipole-dipole correlations which manifests itself differently in these liquid crystalline phases.

A coarse-grained model of ionic liquid crystals: the effect of stoichiometry on the stability of the ionic nematic phase

2019 ◽  
Vol 21 (36) ◽  
pp. 20327-20337 ◽  
Author(s):  
Giacomo Saielli ◽  
Katsuhiko Satoh
Keyword(s):  
Ionic Liquid ◽  
Nematic Phase ◽  
Stoichiometric Composition ◽  
Charged Particles ◽  
Coarse Grained ◽  
Thermal Range ◽  
Coarse Grained Model ◽  
Lennard Jones ◽  
Ionic Liquid Crystals ◽  
The Stability

The thermal range of the ionic nematic phase is strongly influenced by the stoichiometric composition of the [GB]n[LJ]msalt in mixtures of Gay-Berne and Lennard-Jones charged-particles.

Critical behaviour at the nematic–smectic A phase transition in a binary mixture showing induced nematic phase

RSC Advances ◽  
2014 ◽  
Vol 4 (38) ◽  
pp. 19861 ◽  
Author(s):  
Sudipta Kumar Sarkar ◽  
Malay Kumar Das
Keyword(s):  
Phase Transition ◽  
Binary Mixture ◽  
Nematic Phase ◽  
Critical Behaviour ◽  
Smectic A ◽  
Smectic A Phase

Miscibility Studies Indicating a Low Temperature Smectic A Phase in Biaromatic Liquid Crystals with Re-entrant Behaviour

1981 ◽  
Vol 36 (11) ◽  
pp. 1201-1204
Author(s):  
A. Göbl-Wunsch ◽  
G. Heppke ◽  
R. Hopf
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Chain Length ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Alkyl Chain ◽  
Alkyl Chain Length ◽  
Smectic A ◽  
Smectic A Phase ◽  
Miscibility Studies

Recent reports [1] have shown that compounds of the homologous series of the 4(4-n-alkyloxy- benzoyloxy)-4′-cyanoazobenzenes (Cn; n = 1 - 12), all have a low temperature smectic A phase (SA″). The homologues with alkyl chain length n≧9 exhibit in addition a high temperature smectic A phase (SA′), separated from the first one by a re-entrant nematic phase (N(re)). Homol­ogues of this series were used for miscibility studies with some compounds of the biaromatic liquid crystal series of the 4-cyano-4′-n-alkyloxybiphenyls (n̄ CBP) and of the 4-cyanobenzylidene- 4′-n-alkyloxyanilines (CN · n̄). The phase diagrams studied show that the smectic A phases of biaromatic liquid crystalline nitrile compounds correspond to the high temperature smectic SA′ type and are not miscible with the low temperature SA″ phase. Moreover, the shapes of the transition temperature curves to the SA″ phase indicate a low temperature smectic A phase (SA″) for the biaromatic compounds. This suggests that for biaromatic compounds with re-entrant behaviour, the dependence of liquid crystalline phase sequences on the alkyl chain length is very similar to that of triaromatic compounds.

scholarly journals Molecular length distribution and the formation of smectic phases

2009 ◽  
Vol 5 ◽  
Author(s):  
Nadia Kapernaum ◽  
C Scott Hartley ◽  
Jeffrey C Roberts ◽  
Robert P Lemieux ◽  
Frank Giesselmann
Keyword(s):  
Nematic Phase ◽  
Length Distribution ◽  
Stable Phase ◽  
General Interest ◽  
Structure And Dynamics ◽  
Smectic A ◽  
Smectic C ◽  
Smectic Phases ◽  
Molecular Length ◽  
Smectic A Phase

The phase diagrams of two mixtures of chemically similar smectogenic mesogens strongly differing in molecular length were investigated. In these mixtures the nematic phase present in the pure short mesogen disappeared rapidly on the addition of the longer mesogen, while the smectic state was preserved. In the smectic state the smectic A phase was the much more stable phase as the smectic C phase disappeared quite rapidly as well. In these compounds the loss of the smectic C phase is accompanied by a decrease in smectic translational order and very small tilt angles. This leads to a concentration induced smectic C to smectic A transition. Thus smectic A seems to be the most stable phase to accommodate mesogenic molecules of substantially different length. These surprising results are of general interest for the understanding of the structure and dynamics of smectic phases, as the structure of these bidisperse smectics is signified by extensive out-of-layer fluctuations.

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