Study of the Liquid Crystalline Phases in Some Compounds of 4-Trans-(4-Alkyl)Cyclo-Hexylphenyl-Alkylcarboxylate

1983 ◽  
Vol 38 (12) ◽  
pp. 1362-1364 ◽  
Author(s):  
I. H. Ibrahim ◽  
W. Haase
Keyword(s):  
Differential Scanning Calorimetry ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Intermolecular Distance ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Enthalpy Changes ◽  
Liquid Crystalline Phases ◽  
Nematic Phases

Abstract Three mesogenic compounds of the general formula have been investigated by differential scanning calorimetry. thermal optical microscopy and X-ray diffraction methods/Enthalpy changes of The different phase transitions for these compounds have been determined. H33 exhibits smectic B and nematic phases, whereas H34 and H75 exhibit only smectic B phases. The thickness of the smectic layers and the average intermolecular distance have been evaluated, as well as the corresponding molecular parameters in the nematic phase.

scholarly journals Synthesis and mesomorphic properties of calamitic malonates and cyanoacetates tethered to 4-cyanobiphenyls

2012 ◽  
Vol 8 ◽  
pp. 371-378 ◽  
Author(s):  
Katharina C Kress ◽  
Martin Kaller ◽  
Kirill V Axenov ◽  
Stefan Tussetschläger ◽  
Sabine Laschat
Keyword(s):  
Differential Scanning Calorimetry ◽  
Ambient Temperature ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Cyanoacetic Acid ◽  
Scanning Calorimetry ◽  
Isotropic Liquid ◽  
X Ray ◽  
Nematic Phases ◽  
Mesomorphic Properties

4-Cyano-1,1'-biphenyl derivatives bearing ω-hydroxyalkyl substituents were reacted with methyl 3-chloro-3-oxopropionate or cyanoacetic acid, giving liquid-crystalline linear malonates and cyanoacetates. These compounds formed monotropic nematic phases at 62 °C down to ambient temperature upon cooling from the isotropic liquid. The mesomorphic properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction (WAXS).

Inosose-Flüssigkristalle / Inosose Liquid Crystals

1990 ◽  
Vol 45 (7) ◽  
pp. 1084-1090 ◽  
Author(s):  
Klaus Praefcke ◽  
Bernd Kohne ◽  
Andreas Eckert ◽  
Joachim Hempel
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
High Temperature ◽  
Liquid Crystalline ◽  
Structural Features ◽  
Lyotropic Liquid Crystal ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Alkyl Chains

Six S,S-dialkyl acetals 2a-f of inosose (1), tripodal in structure, have been synthesized, characterized and investigated by optical microscopy and differential scanning calorimetry (d.s.c.). The four S,S-acetals 2c-f with sufficiently long alkyl chains are thermotropic liquid crystalline; 2 e and 2 f are even dithermomesomorphic. Each of these four inosose derivatives 2c-f exhibits monotropically a most likely cubic mesophase (MI); in addition 2e and 2f show enantiotropically a hexagonal mesophase (Hx) with a non-covalent, supramolecular H-bridge architecture. Whereas the nature of the optically isotropic mesophase MI needs further clarification the stable high temperature mesophase Hx of 2 e and 2 f has been established by a miscibility test using a sugar S,S-dialkyl acetal also tripodal in structure and with a Hx phase proved by X-ray diffraction, but in contrast to 2 with an acyclic hydrophilic part. Similarities of structural features between the Hx-phases of 2e and 2f as well as of other thermotropic and lyotropic liquid crystal systems are discussed briefly.

A new family of bent-core C2-symmetric liquid crystals

2010 ◽  
Vol 88 (7) ◽  
pp. 639-645 ◽  
Author(s):  
Kyle A. Hope-Ross ◽  
Paul A. Heiney ◽  
John F. Kadla
Keyword(s):  
Differential Scanning Calorimetry ◽  
Small Angle ◽  
Liquid Crystalline ◽  
Side Chains ◽  
Scanning Calorimetry ◽  
X Ray ◽  
New Family ◽  
X Ray Scattering ◽  
Factors Influencing ◽  
Liquid Crystalline Phases

A series of C2-symmetric compounds with different core sizes and varying lengths and numbers of alkoxy side chains were prepared, and the factors influencing their liquid crystalline mesophase behaviour were investigated. The compounds studied were based on benzophenone, dibenzylidene-acetone, and 1,9-diphenyl-nona-1,3,6,8-tetraen-5-one cores with either 1 or 2 linear alkoxy side chains. The side chains were varied in length from C6H13 to C12H25. The liquid crystalline mesophase behaviour of the compounds was investigated using differential scanning calorimetry, polarizing optical microscopy, and small-angle X-ray scattering (SAXS). It was found that a number of the molecules were able to self-assemble into smectic and nematic liquid crystalline phases.

In-Situ Characterisation of Precipitation in AI-Cu thin films

1999 ◽  
Vol 562 ◽  
Author(s):  
J. P. Lokker ◽  
A. J. Bottger ◽  
G. C. A. M. Janssen ◽  
S. Radelaar
Keyword(s):  
Thin Films ◽  
Differential Scanning Calorimetry ◽  
Bulk Material ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Enthalpy Changes ◽  
Thin Foils ◽  
Lower Temperature

ABSTRACTThe precipitate formation occurring in Al-Cu thin foils with copper concentrations of either 1.15 at.% or 0.3 at.%, has been studied. In-situ X-ray diffraction analysis and differential scanning calorimetry are applied to determine the phases formed and the enthalpy changes in the same samples. Both X-ray diffraction and differential scanning calorimetry indicate that the precipitation behaviour of thin films (about 500 nm thickness) differs significantly from that of bulk material. In the films studied the precipitation of Al2Cu occurs at a much lower temperature than expected on the basis of the (bulk) phase diagram. Moreover, no intermediate phases are observed prior to Al2Cu precipitation. Also the amount of Cu in solid solution (0.20 at%Cu) observed by electron-probe micro-analysis after slowly cooling from 500°C to room temperature, exceeds the solubility of bulk Al-Cu.

Thermal and X-Ray Studies of 1,6-Bis-[4-(trans-4-n-propylcyclohexyl) phenyl]-hexane and 3,5-Bis-[4-(trans-4-n-propylcyclohexyl) phenyl]-1,2,4-thiadiazol

1987 ◽  
Vol 42 (7) ◽  
pp. 774-776
Author(s):  
I. H. Ibrahim ◽  
W. Haase
Keyword(s):  
Nematic Phase ◽  
Liquid Crystalline ◽  
Layer Structure ◽  
Mass Density ◽  
Density Fluctuations ◽  
Smectic Layer ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Liquid Crystalline Phases ◽  
Diffraction Patterns

The liquid crystalline phases of the title compounds have been investigated by differential scanning calorimetry, optical microscopy and X -ray diffraction methods. Transition temperatures and transition enthalpies of these compounds have been determined. The diffraction photographs in the nematic phase of the first compound showed diffraction patterns corresponding to two coexisting mass density fluctuations with commensurate wavelengths, whereas a single diffraction pattern was observed in the nematic phase of the second compound. The thermal and X -ray data showed that the first compound has a quasi-smectic layer structure.

scholarly journals Synthesis, liquid crystalline behaviour and structure–property relationships of 1,3-bis(5-substituted-1,3,4-oxadiazol-2-yl)benzenes

2020 ◽  
Vol 16 ◽  
pp. 149-158
Author(s):  
Afef Mabrouki ◽  
Malek Fouzai ◽  
Armand Soldera ◽  
Abdelkader Kriaa ◽  
Ahmed Hedhli
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystalline ◽  
Dipole Moments ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Rigid Core ◽  
X Ray ◽  
Structure Property Relationships ◽  
Crystal Properties

Two series containing 1,3-bis(1,3,4-oxadiazol-2-yl)benzene as a rigid core (RC) and alkyl or perfluoroalkyl as terminal chains were synthesized and characterized. Liquid crystal properties of the synthesized compounds have been investigated by polarizing optical microscopy, differential scanning calorimetry and X-ray diffraction techniques. Conformation effects of the synthesized products on the dipole moments were also investigated.

Synthesis and Phase Behavior of Polysiloxane Nematic Liquid Crystal Elastomers

2012 ◽  
Vol 535-537 ◽  
pp. 1185-1188 ◽  
Author(s):  
Ying Gang Jia ◽  
Kun Ming Song ◽  
Bao Yan Zhang
Keyword(s):  
Differential Scanning Calorimetry ◽  
Phase Behavior ◽  
Liquid Crystalline ◽  
Side Chain ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
One Step ◽  
Liquid Crystal Elastomers ◽  
Reversible Phase

This paper describes the synthesis of new side chain nematic liquid crystalline elastomers (LCEs) by a one-step hydrosilication reaction. The phase behavior and mesomorphism were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and x-ray diffraction (XRD). The effect of the content of crosslinking units on the phase behavior and mesomorphism of elastomers P1 – P8 was discussed. The nematic LCEs exhibit elasticity, reversible phase transitions, and nematic thread texture. The experimental results demonstrate that the glass transition temperature and isotropic temperature of nematic LCEs decreased with increasing the content of crosslinking unit.

Synthesis and Properties of Liquid Crystalline Polyurethanes from 4,4-bis (6-hydroxyhexoxy) Biphenyl and 3,3'-Dimethyl-4, 4’-Biphenylene Diisocyanate

2010 ◽  
Vol 428-429 ◽  
pp. 144-149
Author(s):  
Xiao Dong Chen ◽  
Nan Qiao Zhou ◽  
Hai Zhang
Keyword(s):  
Nematic Phase ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Decomposition Temperature ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Temperature Range

A thermotropic liquid crystalline polyurethane (LCPU) was synthesized by the polyaddition reaction of 3,3'-dimethyl-4,4'-biphenylene diisocyanate (TODI) with 4,4-bis(6-hydroxyhexoxy)biphenyl (BHHBP). The liquid crystalline behavior of the polymer was investigated by differential scanning calorimetry (DSC), polarized optical microscopy (POM), wide angle X-ray diffraction (WAXD). The LCPU exhibited a nematic phase with a threaded texture and had a wide mesophase temperature range. And thermogravimetric analysis (TGA) indicated the decomposition temperature of the LCPU was >300°C. The observation of POM showed that the LCPU was a thermotropic nematic liquid crystalline polymer at certain temperature range.

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