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.

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

2019 ◽  
Author(s):  
Afef Mabrouki ◽  
Malek Fouzai ◽  
Armand Soldera ◽  
Abdelkader Kriaa ◽  
ahmed hedhli
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
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.

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.

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.

Synthesis and Liquid Crystalline Properties of New Chiral Monomers and Polysiloxanes

2013 ◽  
Vol 815 ◽  
pp. 747-751
Author(s):  
Jian She Hu ◽  
Yi Nan Liu ◽  
Ya Ting Song ◽  
Di Wang
Keyword(s):  
Liquid Crystalline ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Cholesteric Phase ◽  
Crystalline Materials ◽  
H Nmr ◽  
Structure Property Relationships ◽  
Potential Applications ◽  
Liquid Crystalline Materials

To study the structure-property relationships of new chiral liquid crystalline materials based on menthol and explore their potential applications, a monomer 4-(4-allyloxybenzoyloxy) phenyl-4-menthyl-oxyacetyloxybiphenyl-4-carboxylate (LCM) and the corresponding homopolymer (LCP) were synthesized. The chemical structure was characterized by FT-IR and 1H NMR. The liquid crystalline properties were investigated by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X-ray diffraction. The monomer LCM formed a cholesteric phase when a flexible linkage chain was inserted between the mesogenic core and the terminal menthyl groups by reducing the steric effect. The homopolymer LCP exhibited a batonnet texture of a smectic A phase.

Preparation of poly(ether ketone)s having phenyl, biphenyl, and terphenyl side groups and comparison of their properties

2016 ◽  
Vol 30 (1) ◽  
pp. 67-75 ◽  
Author(s):  
Satoshi Kawaguchi ◽  
Atsushi Morikawa
Keyword(s):  
Phenylboronic Acid ◽  
Cross Coupling ◽  
Side Group ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Structure Property Relationships ◽  
Linear Poly ◽  
Ether Ketone

Three kinds of bis(aromatic fluoride) compounds, 3,5-bis(4-fluorobenzoyl)biphenyl (1), 3,5-bis(4-fluorobenzoyl)-1,1′:4′,1″-terphenyl (2), and 3,5-bis(4-fluorobenzoyl)-1,1′:4′,1″:4″,1′′′-quaterphenyl (3), were synthesized by cross-coupling of the corresponding triflates with phenylboronic acid. Linear poly(ether ketone)s (1x, 2x, and 3x) having phenyl, biphenyl, and terphenyl side groups, respectively, were prepared by the polycondensation of the bis(aromatic fluoride) compounds with bisphenol A (a) and 4,4′-dihydroxybiphenyl (b) in N-methyl-2-pyrrolidone. The obtained poly(ether ketone)s were characterized by X-ray diffraction, differential scanning calorimetry, and thermogravimetry. The structure–property relationships of these poly(ether ketone)s were examined and compared with those of poly(ether ketone)s (4x) having no side group, which were prepared from 3,5-bis(4-fluorobenzoyl)benzene (4). The properties of the poly(ether ketone)s, solubilities, and thermal properties were compared and discussed based on the length of the side groups.

Synthesis and properties of polyimides from 1,4-bis(4-amino-2-phenylphenoxy) benzene and 4,4′-bis(4-amino-2-phenylphenoxy) biphenyl

2012 ◽  
Vol 24 (8) ◽  
pp. 783-792 ◽  
Author(s):  
Atsushi Morikawa ◽  
Fumi Miyata ◽  
Jun Nishimura
Keyword(s):  
Ring Opening ◽  
Mechanical Analysis ◽  
Ring Opening Polymerization ◽  
Dielectric Constants ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Structure Property Relationships ◽  
Step Procedure

Diamines, namely, 1,4-bis(4-amino-2-phenylphenoxy) benzene (1) and 4,4′-bis(4-amino-2-phenylphenoxy) biphenyl (2), were synthesized from 4-fluoro-3-phenyl nitrobenzene. Two series of polyimides were synthesized from these diamines with nine types of dianhydrides by a conventional two-step procedure that included ring-opening polymerization in N-methyl-2-pyrrolidone and subsequent thermal cyclic dehydration. The polyimides were characterized by x-ray diffraction, differential scanning calorimetry, thermogravimetry and dynamic mechanical analysis. The polyimides from 1 and 2 had a glass transition temperature in the range of 221–254°C and 222–271°C, respectively, and all the polymers were amorphous. The structure–property relationships of these polyimides were examined and compared with those of the previously prepared analogous polyimides from the bis(4-amino-2-biphenyl)ether (3). Water absorption and dielectric constants ( ∊) of the polyimides were compared and discussed on the basis of imide content per repeating unit.

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 Novel Thiophene-Based Liquid Crystalline Conducting Polymers

2017 ◽  
Vol 25 (9) ◽  
pp. 669-676 ◽  
Author(s):  
Danesh Roudini
Keyword(s):  
Magnetic Field ◽  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Optical Microscopy ◽  
Electronic Properties ◽  
Liquid Crystalline ◽  
Side Chain ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Crystal Properties

Side-chain liquid crystalline polythiophenes were synthesised and the effects of the mesogenic units on the structure and electronic properties of the polymers were studied. The liquid crystal properties of the polymer films were studied using polarised hot-stage optical microscopy and differential scanning calorimetry, and X-ray diffractometry was used to investigate the effect of a magnetic field on the monomers and polymers.

Sign in / Sign up

Export Citation Format

Share Document