scholarly journals Synthesis, Characterization and Study of Mesomorphic Behavior of New Bent and Liner Core Compounds Containing Heterocyclic

2017 ◽  
Vol 30 (3) ◽  
pp. 195
Author(s):  
Nisreen H. Karam ◽  
Alaa K. Shanshal
Keyword(s):  
Liquid Crystals ◽  
Schiff Bases ◽  
Aromatic Amines ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Thioglycolic Acid ◽  
Melting Points ◽  
Scanning Calorimetry ◽  
Phosphorous Oxychloride ◽  
Compound Xvii

  We described herein the synthesized and characterized of new bent and liner core compounds containing thiazolidin-4-one ring[XI-XIII] and [XIV-XVI] respectively. These compounds synthesized by sequence reactions starting from reaction resorcinol or hydroquinone with chloracetyl chloride to yield compounds [I] and [II] ,then the later compounds reactant with 4-hydroxybenzylaldehyde to product dialdehyde compounds [III] and [IV] .The Schiff bases compounds[V-VII] and [VIII-X] synthesized from reaction the compound [III] or [IV] with different aromatic  amines, while the bent and liner core mesogens containing thiazolidin-4-one ring [XI-XIII] and [XIV-XVI] synthesized from reaction Schiff bases compounds[V-VII] or  [VIII-X] with thioglycolic acid. In addition estrfecation of cinnamic acid with methanol to yield ester compound[XVII]which was converted to their acid hydrazid[XVIII] and the acid hydrazid reacted with glysine in phosphorous oxychloride to yield (5-styryl-1,3,4-oxadiazol-2-yl) methanamine [XIX]. Then reactant the1,3,4-oxadiazol compound[XIX]    with dialdehyde compound [III] or  [IV] to product new Schiff bases compounds [XX] and [XXI]  , afterword added thioglycolic acid to give new thiazolidin-4-one derivatives [XXII] and [XXIII], respectively.        The synthesized compounds were characterized by melting points , FTIR ,1HNMR and mass spectroscopy (of some of them).The liquid crystalline properties were studied by hot stage polarized optical microscopy (POM) and differential scanning calorimetry(DSC).All the  Schiff bases compounds [V-X] showed liquid crystals phases while thiazolidin-4-one derivatives[XI-XIII],[XIV-XVI]and [XXIII] didn’t show any liquid crystals properties except the compound [XXII] showed enantiotropic nematic phase.

scholarly journals Temperature-Dependent X-Ray Studies of Discotic Hexagonal Columnar Mesophases in Trinuclear Gold(I) Pyrazolate Complex

2021 ◽  
Vol 17 (3) ◽  
pp. 285-294
Author(s):  
Mohamad Azani Abd Khadir Jalani ◽  
Hendrik O. Lintang ◽  
Siew Ling Lee ◽  
Juan Matmin ◽  
Nur Fatiha Ghazalli ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Variable Temperature ◽  
Gold Complex ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Heating And Cooling ◽  
Depth Study ◽  
Columnar Mesophases ◽  
Hexagonal Columnar

Gold(I) pyrazolate complex ([Au3Pz3]C10TEG) has been widely studied due to its interesting liquid crystalline properties by exhibiting the discotic hexagonal columnar arrangement. Generally, the liquid crystalline properties of the gold complex were confirmed based on their differential scanning calorimetry thermogram and polarized optical microscopy (POM) images. However, there is still no in-depth study on the phase transition in liquid crystals of [Au3Pz3]C10TEG especially on its structural change at variable temperature. In this study, the resulting liquid crystalline properties of [Au3Pz3]C10TEG upon being heated and cooled was extensively demonstrated via variable-temperature POM (VT-POM) and small angle X-ray scattering (VT-SAXS). Based on the VT-POM images, it was indicated that [Au3Pz3]C10TEG displayed a fan-shaped texture for typical arrangements of discotic hexagonal columnar of liquid crystals. Moreover, VT-SAXS results was in good agreement with the VT-POM images as it showed that [Au3Pz3]C10TEG might consist of two types of stacking system, which are ordered and disordered hexagonal discotic arrangements. Likewise, VT-SAXS analysis also demonstrated that hexagonal columnar mesophase of [Au3Pz3]C10TEG could be recovered even after the heating and cooling for two cycles.

scholarly journals Order Parameters, Orientational Distribution Functions and Heliconical Tilt Angles of Oligomeric Liquid Crystals

2019 ◽  
Author(s):  
Richard Mandle ◽  
John W. Goodby
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Tilt Angle ◽  
Order Parameter ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Thermal Evolution ◽  
Order Parameters ◽  
Distribution Functions ◽  
Orientational Distribution

We compare the order parameters, orientational distribution functions (ODF) and heliconical tilt angles of the TB phase exhibited by a liquid-crystalline dimer (CB7CB) to a tetramer (O47) and hexamer (O67) by SAXS/WAXS. Following the N-TB phase transition we find that all order parameters decrease, and while 〈P2 〉 remains positive 〈P4 〉 becomes negative. For all three materials the order parameter 〈P6 〉 is near zero in both phases. The ODF is sugarloaf-like in the nematic phase and volcano-like in the TB phase, allowing us to estimate the heliconical tilt angle of each material and its thermal evolution. The heliconical tilt angle appears to be largely independent of the material studied despite the differing number of mesogenic units.

Two New Thermotropic Liquid Crystalline Polyesters and their Composites: Synthesis and Characterization

2009 ◽  
Vol 87-88 ◽  
pp. 154-159
Author(s):  
Chuan Ji Zhang ◽  
Zhi Xiong Huang ◽  
Min Xian Shi ◽  
Ming Zhang
Keyword(s):  
Mechanical Properties ◽  
Liquid Crystalline ◽  
Synthesis Process ◽  
Differential Scanning Calorimetric ◽  
Melting Points ◽  
Texture Characteristic ◽  
Scanning Calorimetry ◽  
Heating And Cooling ◽  
Melt Polycondensation ◽  
Monomer Structure

Two new series of liquid crystalline polyesters were synthesized using melt polycondensation reaction.Glass fiber,as a reinforcement,was meltpolymerized with 4-acetoxybenzoic(ABA),4,4＇-diacetoxybiphenyl, isophthalic acid(IA) and terephthalic acid(TA) to make TLCP/GF composites with a good mechanical properties.All the obtained compounds were characterized by conventional spectroscopic methods. The structure of the target compounds and intermediates was conformed by the IR, 1H NMR and SEM. The thermal behavior of the polymers has been characterized using polarized optical microscopy and differential scanning calorimetry. The effect of monomer structure and mechanical properties has been investigated on the prepared polyesters. These compounds show a high birefringent Schlierene texture characteristic of the nematic phase on heating and cooling experiments. This was further confirmed using differential scanning calorimetric investigations.The melting points of polymers having a central 4,4’-biphenyldicarboxylate residue have broad endotherms. The glass transition temperature values of polyesters are not effect by the glass fiber.According to the SEM result showed that the composite had strong fiber-matrix adhesion.The effect of copolymerization with added glass fiber in synthesis process is compared with that of the anlogous homopolyesters by other processing mode.Our finding shows that the copolymers exhibit reduced technical process and maintained mechanical properties.

Phase Transition Behavior of Main Chain Nematic Liquid-Crystalline Polymers Based on 2-methyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone and 2-tert-butyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone

2012 ◽  
Vol 1403 ◽  
Author(s):  
Christain Melchert ◽  
M. Behl ◽  
A. Lendlein
Keyword(s):  
Phase Transition ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Phase Transition Behavior ◽  
Scanning Calorimetry ◽  
Thermal Stabilities ◽  
Crystalline Polymers ◽  
Transition Behavior ◽  
X Ray Scattering

ABSTRACTThe control of phase transition behavior in liquid crystalline polymers could enable potential application in the field of actuators and sensors by enabling a higher actuator performance of liquid crystalline elastomers (LCE). In this context the phase transition behavior of siloxane based liquid crystalline copolymers synthesized from 1,1,3,3-tetramethyldisiloxane, 2-methyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone (M-MeHq), and 2-tert-butyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone (M-tBHq) was explored. The selected monomers provided different thermal stabilities of the nematic phase, while the non-flexible siloxane spacer suppressed a smectic phase. The mesogenic properties were studied by means of differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and wide angle X-ray scattering (WAXS). With increasing fraction of M-MeHq the nematic phase of the copolymer was stabilized and a tailoring of relatively low TNI was achieved.

Chromonic liquid crystalline nematic phase exhibited in binary mixture of two liquid crystals

2015 ◽  
Author(s):  
T. N. Govindaiah ◽  
H. R. Sreepad ◽  
K. N. Sridhar ◽  
G. R. Sridhara ◽  
N. Nagaraja
Keyword(s):  
Liquid Crystals ◽  
Binary Mixture ◽  
Nematic Phase ◽  
Liquid Crystalline

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.

Polymerization and Properties of Polymer-Stabilized Ferroelectric Liquid Crystals

MRS Bulletin ◽  
1997 ◽  
Vol 22 (9) ◽  
pp. 15-20 ◽  
Author(s):  
Christopher N. Bowman ◽  
C. Allan Guymon
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Scanning Calorimetry ◽  
Ferroelectric Liquid Crystals ◽  
University Of Colorado ◽  
Crystalline Environment ◽  
Polarized Infrared Spectroscopy ◽  
The Many ◽  
The University ◽  
Polymer Stabilized

The following is based on the presentation made by Christopher N. Bowman, recipient of the MRS Outstanding Investigator Award, at the 1997 MRS Spring Meeting.I would like to focus on our recent work involving photopolymerizations of monomers in a liquid-crystalline environment. This work is one of the many aspects of photopolymerizations that we are focusing on at the University of Colorado. In particular this effort concentrates on understanding the influence of a liquid-crystalline medium and monomer segregation on polymerization behavior and polymer structure. These studies are of considerable importance for polymer-stabilized ferroelectric liquid crystals (FLCs) because of the enormous potential impact on the area.I will briefly introduce liquid crystals (LCs), FLCs, and photopolymerizations. I will then discuss the observed electrooptic properties and how these properties change as the LC phase during polymerization is varied. Finally I will address how polymerization kinetics are affected by the LC phase and monomer segregation. This discussion will include results from x-ray diffraction, polarized infrared spectroscopy, and differential scanning calorimetry experiments.

scholarly journals Synthesis and characteristics of novel azo-based diblock copolymers and their self-assembly behavior via solvents and thermal annealing

e-Polymers ◽  
2017 ◽  
Vol 17 (6) ◽  
pp. 523-535 ◽  
Author(s):  
Athmen Zenati ◽  
Yang-Kyoo Han
Keyword(s):  
Self Assembly ◽  
Nematic Phase ◽  
Weight Control ◽  
Liquid Crystalline ◽  
Diblock Copolymers ◽  
Raft Polymerization ◽  
Gel Permeation Chromatography ◽  
Kinetic Studies ◽  
Morphological Properties ◽  
Scanning Calorimetry

AbstractA series of azo-based diblock copolymers (DBCs) with various compositions were successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization in anisole with PCAEMA-CTA (macro-CTA), DOPAM (new acrylamide monomer) and AIBN (initiator). Kinetic studies on diblock copolymerization manifested a controlled/living manner with good molecular weight control. Structures and properties of monomers and DBCs were determined by 1H nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). Liquid crystalline (LC) phases and morphological properties were investigated using optical polarizing microscope (OPM), atomic force microscopy (AFM), scanning electron microscopy (SEM) and small-angle X-ray scattering (SAXS). Experimental results demonstrated that the prepared PCAEMA-CTA and DBCs possessed low polydispersity index (≤1.37). All DBCs revealed sharp endothermic transition peaks corresponding to the smectic-to-nematic phase. DBCs with high azo contents showed batonnet textures of the smectic phase whereas DBCs of low azo segments displayed threaded textures of the nematic phase. DBC with 49 wt% of azo side-chains generated a lamellar compared to DBCs with low azo block (≤41 wt%) or non-azo block (≤38 wt%) which produced hexagonal-type nanostructures. In addition, all DBCs exhibited reversible trans-cis photoisomerization behavior under UV irradiation and dark storage at different intervals of time.

scholarly journals Oxadiazolyl-Pyridinium as Cationic Scaffold for Fluorinated Ionic Liquid Crystals

2021 ◽  
Vol 11 (21) ◽  
pp. 10347
Author(s):  
Melina S. Weber ◽  
Margit Schulze ◽  
Giuseppe Lazzara ◽  
Antonio Palumbo Piccionello ◽  
Andrea Pace ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Alkyl Chain ◽  
Scanning Calorimetry ◽  
New Class ◽  
Structural Variables ◽  
Ionic Liquid Crystals ◽  
Thermotropic Properties

The synthesis and characterization of a new class of 1,2,4-oxadiazolylpyridinium as a cationic scaffold for fluorinated ionic liquid crystals is herein described. A series of 12 fluorinated heterocyclic salts based on a 1,2,4-oxadiazole moiety, connected through its C(5) or C(3) to an N-alkylpyridinium unit and a perfluoroheptyl chain, differing in the length of the alkyl chain and counterions, has been synthesized. As counterions iodide, bromide and bis(trifluoromethane)sulfonimide have been considered. The synthesis, structure, and liquid crystalline properties of these compounds are discussed on the basis of the tuned structural variables. The thermotropic properties of this series of salts have been investigated by differential scanning calorimetry and polarized optical microscopy. The results showed the existence of an enantiotropic mesomorphic smectic liquid crystalline phase for six bis(trifluoromethane)sulfonimide salts.

scholarly journals Substituted Azolium Disposition: Examining the Effects of Alkyl Placement on Thermal Properties

Crystals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 34 ◽  
Author(s):  
Karel Goossens ◽  
Lena Rakers ◽  
Tae Shin ◽  
Roman Honeker ◽  
Christopher Bielawski ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Polarized Light ◽  
Melting Points ◽  
Scanning Calorimetry ◽  
Imidazolium Chloride ◽  
X Ray ◽  
Smectic A ◽  
X Ray Scattering ◽  
Thermal Phase ◽  
Azolium Salts

We describe the thermal phase characteristics of a series of 4,5-bis(n-alkyl)azolium salts that were studied using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), polarized-light optical microscopy (POM), and synchrotron-based small- to wide-angle X-ray scattering (SWAXS) measurements. Key results were obtained for 1,3-dimethyl-4,5-bis(n-undecyl)imidazolium iodide (1-11), 1,3-dimethyl-4,5-bis(n-pentadecyl)- imidazolium iodide (1-15), and 1,2,3-trimethyl-4,5-bis(n-pentadecyl)imidazolium iodide (2), which were found to adopt enantiotropic smectic A mesophases. Liquid-crystalline mesophases were not observed for 1,3-dimethyl-4,5-bis(n-heptyl)imidazolium iodide (1-7), 3-methyl-4,5-bis(n-penta-decyl)thiazolium iodide (3), and 2-amino-4,5-bis(n-pentadecyl)imidazolium chloride (4). Installing substituents in the 4- and 5-positions of the imidazolium salts appears to increase melting points while lowering clearing points when compared to data reported for 1,3-disubstituted analogues.

Sign in / Sign up

Export Citation Format

Share Document