scholarly journals Design of polar self-assembling lactic acid derivatives possessing submicrometre helical pitch

2018 ◽  
Vol 9 ◽  
pp. 333-341 ◽  
Author(s):  
Alexej Bubnov ◽  
Cyril Vacek ◽  
Michał Czerwiński ◽  
Terezia Vojtylová ◽  
Wiktor Piecek ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Liquid Crystalline ◽  
Room Temperature ◽  
Scanning Calorimetry ◽  
Alkyl Chains ◽  
Temperature Range ◽  
Helical Pitch ◽  
Self Assembling ◽  
Electro Optic ◽  
Nanoscale Level

Several new lactic acid derivatives containing the keto linkage group far from the chiral part and short alkyl chains have been synthesized and characterised by polarising optical microscopy, differential scanning calorimetry, as well as electro-optic and dielectric spectroscopy. The materials possess a self-assembling behaviour on the nanoscale level as they form polar smectic liquid crystalline mesophases, namely the orthogonal paraelectric SmA* and the tilted ferroelectric SmC* phases, in a broad temperature range down to room temperature. A short helical pitch (≈120–320 nm), relatively high spontaneous polarisation (≈150 nC/cm2) and reasonable tilt angle values have been determined within the temperature range of the tilted ferroelectric SmC* phase. The obtained results make the new materials useful for the advanced mixture design and for further utilisation in electro-optic devices based on the deformed helix ferroelectric effect.

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.

Design and electro-optic investigations of de Vries chiral smectic liquid crystals for exhibiting broad temperature ranges of SmA* and SmC* phases and fast electro-optic switching

2020 ◽  
Vol 8 (14) ◽  
pp. 4859-4868 ◽  
Author(s):  
V. Swaminathan ◽  
V. P. Panov ◽  
A. Panov ◽  
D. Rodriguez-Lojo ◽  
P. J. Stevenson ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Alkyl Chain ◽  
Smectic Liquid Crystals ◽  
Switching Speed ◽  
Temperature Range ◽  
Electro Optic ◽  
De Vries ◽  
Temperature Ranges

Two new ferroelectric liquid crystalline compounds using 5-phenyl-pyrimidine core terminated by achiral trisiloxane chain, and chiral (S) alkyl chain on the opposite ends of their respective mesogens are designed with better characteristics of switching speed and broader temperature range.

The Pyrolytic Decomposition of Owens-Illinois Resin Gr650, an Organosilicon Compound

1984 ◽  
Vol 32 ◽  
Author(s):  
B. G. Bagley ◽  
P. K. Gallagher ◽  
W. E. Quinn ◽  
L. J. Amos
Keyword(s):  
Room Temperature ◽  
Evolved Gas Analysis ◽  
Condensation Reaction ◽  
Gas Analysis ◽  
Weight Loss Curve ◽  
Reaction Products ◽  
Scanning Calorimetry ◽  
Evolved Gas ◽  
Temperature Range ◽  
Pyrolytic Decomposition

ABSTRACTThe pyrolytic conversion of an organosilsesquioxane (Owens-Illinois resin GR650) to SiO2 is characterized by ir spectroscopy, thermogravimetry and evolved gas analysis (line-of-sight mass spectroscopy). Scanning calorimetry, ramping at 10°C/min, on the as-received (room temperature annealed) resin indicates a glass transition temperature of 67°C which decreases to 58°C for an unrelaxed sample. The ir spectra have bands which can be assigned to Si-CH3 and Si-O-Si modes. For 30 minute isothermal anneals at temperatures above 420°C there is a continuous decrease in the bands associated with the Si-CH3 groups such that after 30 minutes at 650°C the ir spectrum has evolved to that for SiO2. Evolved gas analysis indicates that there are four major components evolving. Over the temperature range (ramping at 10°C/min) ∼180 to ∼500°C we observe C2H5OH and H2O, both of which are condensation reaction products from the curing reaction. Methane is a major evolving species over the temperature range ∼500 to ∼800°C and the thermal spectrum is double peaked which we attribute to CH3+ bound to the inside and outside of the polymer cage structures. The final major component detected was H2, over the temperature range ∼600 to ∼1100°C, which was attributed to pyrolysis of the organic components, both trapped and evolving. The features of the weight loss curve can be accounted for by the measured evolving species spectra.

scholarly journals Liquid Crystalline Compounds in the Thiophene Series, Part 6+ Synthesis and Characterization of Azomethines and Vinylenes with Two Mesogenic Groups and Different Alkylene Spacer Lengths

1993 ◽  
Vol 48 (6) ◽  
pp. 826-843 ◽  
Author(s):  
Gerhard Koßmehl ◽  
Frank Dirk Hoppe ◽  
Barbara Hirsch
Keyword(s):  
Aromatic Amines ◽  
Liquid Crystalline ◽  
Synthesis And Characterization ◽  
Scanning Calorimetry ◽  
Polarizing Microscopy ◽  
Alkyl Chains ◽  
Liquid Crystalline Phases ◽  
Smectic Mesophase ◽  
Methylene Groups

Compounds which have two mesogenic groups with and without terminal alkyl chains containing thiophene systems, were prepared from α.ω-bis(5-formyl-2-thienyl)alkanes (3a-3n) and various aromatic amines or 2-fluorenyl-Wittig-salt (10). The liquid crystalline properties of these compounds were characterized by differential scanning calorimetry (DSC) and polarizing microscopy. Only the series of α.ω-bis{5-[N-(4′-butyloxybiphenyl-4-yl)imino]formyl-2-thienyl}alkanes (7a-71) showed enantiotropic smectic and nematic mesophases. The series of E,E-α.ω-bis[5-(2-fluorenylvinyl)-2-thienyl]alkanes (8a-81) showed enantiotropic nematic mesophases for the compounds with 4 and 6 methylene groups, monotropic nematic mesophases for the compounds with 7—12 methylene groups and no liquid crystalline phases for compounds with 3, 5, 16 methylene groups in the connecting alkylene chain. In contrast to the compounds 8a-81, E-l-(5-butyl-2-thienyl)-2-(2-fluorenyl)ethylene has a smectic mesophase.

Synthesis and thermotropic properties of hydroxy and silyloxy axially substituted phthalocyanines

2000 ◽  
Vol 04 (05) ◽  
pp. 569-573 ◽  
Author(s):  
BELÉN DEL REY ◽  
M. VICTORIA MARTÍNEZ-DÍAZ ◽  
JOAQUÍN BARBERÁ ◽  
TOMÁS TORRES
Keyword(s):  
Liquid Crystalline ◽  
Room Temperature ◽  
Amorphous Structure ◽  
Axial Position ◽  
X Ray Diffraction ◽  
Polarizing Microscopy ◽  
X Ray ◽  
Temperature Range ◽  
Isotropic Materials ◽  
Thermotropic Properties

Novel boron(III) subphthalocyanines 5-8 with six lipophilic alkylthio chains at the peripheral sites, bearing hydroxy or triethylsilyloxy groups in the axial position, have been synthesized and their thermotropic properties have been studied. These compounds are gelatinous materials at room temperature and gradually soften as the temperature is raised up to a point at which high fluidity typical of classical liquids is observed. By the usual techniques employed for the study of thermotropic behaviour (polarizing microscopy, DSC and X-ray diffraction), no liquid crystalline properties have been found. Instead, the compounds have an amorphous structure (i.e. behave as isotropic materials) throughout the temperature range studied. They could be designated as liquid subphthalocyanines.

scholarly journals Liquid Crystalline Compounds in the Thiophene Series, Part 7+

1993 ◽  
Vol 48 (12) ◽  
pp. 1807-1820 ◽  
Author(s):  
Gerhard Koßmehl ◽  
Frank Dirk Hoppe
Keyword(s):  
Liquid Crystalline ◽  
Phosphonium Salts ◽  
Scanning Calorimetry ◽  
Azomethine Group ◽  
Temperature Range ◽  
H Nmr ◽  
Chemical Structures ◽  
Liquid Crystalline Phases ◽  
Elemental Analyses ◽  
New Compounds

Compounds with two mesogenic groups without terminal alkyl chains or other groups containing thiophene systems have been prepared from α.ω-bis(5-formyl-2-thienyl)alkanes (series 1) and various phosphonium salts by Wittig-reaction. The chemical structures of the new compounds have been characterized by their elemental analyses, IR and 1H NMR spectra and MS. The liquid crystalline properties of these compounds were characterized by differential scanning calorimetry (DSC) and polarizing microscopy. Mesogenic cores with one thiophene system and two benzene systems give rise to liquid crystalline phases. These compounds with one vinylene group in each core (series 2 and 3) are mostly monotropic, those with two or three vinylene groups are enantiotropic liquid crystalline. Exchanging one vinylene group by a azomethine group in each core reduces the temperature range of the mesophase or destroys the liquid crystallinity completely. In contrast to E,E-1-(5-butyl-2-thienylvinyl)-4-(styryl)benzene (9) with no mesophase the corresponding all-E-α.ω-bis{5-[4-(4-styryl)styryl]-2-thienyl}alkanes (series 5) show over a wide temperature range with increasing inner chain length more and more high ordered mesophases. all-E-α.ω-Bis{5-[4-(4-phenylbuta-1.3-dienyl)styryl]-2-thienyl}alkanes (series 7) decompose in their mesophases.

Synthesis and characterization of novel liquid and liquid crystalline phthalocyanines

2004 ◽  
Vol 08 (10) ◽  
pp. 1175-1186 ◽  
Author(s):  
Mahmut Durmuş ◽  
Colette Lebrun ◽  
Vefa Ahsen
Keyword(s):  
Liquid Crystalline ◽  
Room Temperature ◽  
Metal Salt ◽  
Electronic Spectroscopy ◽  
Scanning Calorimetry ◽  
Elemental Analyses ◽  
Columnar Mesophases ◽  
New Compounds ◽  
Hexagonal Columnar

Peripheral and non-peripheral tetra(13,17-dioxanonacosane-15-hydroxy) substituted metal free-, Ni (II) and Zn (II) phthalocyanines have been synthesized from the corresponding phthalonitrile derivatives in the presence of the anhydrous metal salt ( NiCl 2 and Zn ( OOCCH 3)2) or a strong organic base. The new compounds have been characterised by elemental analyses, IR, NMR, mass spectra and electronic spectroscopy. The mesogenic properties of these new materials were studied by differential scanning calorimetry (DSC), optical polarised microscopy and X-ray investigations. The effects of peripheral or non-peripheral substitution of (13,17-dioxanonacosane-15-hydroxy) to the phthalocyanine ring are also investigated. It is found out that non-peripheral substituted phthalocyanine derivatives (4a-c) are liquid at room temperature whereas, peripheral substituted phthalocyanine derivatives (7a-c) exhibit ordered discotic hexagonal columnar mesophases ( Col h) at room temperature.

scholarly journals Thermotropic Liquid-Crystalline and Light-Emitting Properties of Poly(pyridinium) Salts Containing Various Diamine Connectors and Hydrophilic Macrocounterions

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 851 ◽  
Author(s):  
Tae Soo Jo ◽  
Haesook Han ◽  
Pradip K. Bhowmik ◽  
Benoît Heinrich ◽  
Bertrand Donnio
Keyword(s):  
Liquid Crystalline ◽  
Room Temperature ◽  
Variable Temperature ◽  
Green Light ◽  
Pyridinium Salts ◽  
Ionic Polymers ◽  
Excellent Thermal Stability ◽  
Viscous Liquids ◽  
Temperature Range ◽  
Macromolecular Systems

A set of poly(pyridinium) salts containing various diamine moieties, as molecular connectors, and poly(ethyleneglycol)-4-nonylphenyl-3-sulfopropyl ether, thereafter referred to as “Macroion”, as the hydrophilic counterion, were prepared by metathesis reaction from the respective precursory tosylated poly(pyridinium)s in methanol. The structure of these ionic polymers was established by spectroscopy and chromatography techniques. The shape-persistent ionic poly(pyridinium) materials, inserting rigid or semi-rigid diamine spacers, display thermotropic liquid-crystalline properties from room-temperature up to their isotropization (in the temperature range around 160–200 °C). The nature of the LC phases is lamellar in both cases as identified by the combination of various complementary experimental techniques including DSC, POM and variable-temperature SAXS. The other polymers, inserting bulky or flexible spacers, only form room temperature viscous liquids. These new macromolecular systems can then be referred to as polymeric ionic liquid crystals (PILCs) and or polymeric ionic liquids (PILs). All the ionic polymers show excellent thermal stability, in the 260–330 °C temperature range as determined by TGA measurements, and a good solubility in common organic solvents as well as in water. Their optical properties were characterized in both solution and solid states by UV−Vis and photoluminescent spectroscopies. They emit blue or green light in both the states and exhibit a positive solvatochromic effect.

Effect of Thermal Aging on the Transformation Temperatures and Specific Heat Characteristics of 9Cr-1Mo Ferritic Steel

2008 ◽  
Vol 279 ◽  
pp. 85-90 ◽  
Author(s):  
B. Jeya Ganesh ◽  
S. Raju ◽  
E. Mohandas ◽  
M. Vijayalakshmi
Keyword(s):  
Heat Capacity ◽  
Phase Transformation ◽  
Specific Heat ◽  
Room Temperature ◽  
Martensitic Steel ◽  
Thermal Ageing ◽  
Phase Transformation Temperature ◽  
Scanning Calorimetry ◽  
Temperature Range ◽  
Martensite Microstructure

The effect of thermal ageing on the heat capacity and transformation behaviour of behaviour of 9Cr-1Mo-0.1C (wt.%) ferritic / martensitic steel has been studied using differential scanning calorimetry (DSC) in the temperature range 473 to 1273 K. It is found that a-ferrite + carbide ® g-austenite phase transformation temperature is only mildly sensitive to microstructural details; but the enthalpy change associated with this phase transformation and especially, the change in specific heat around the transformation regime are found to be dependent on the starting microstructure generated by thermal ageing treatment. Prolonged ageing for about 500 to 5000 hours in the temperature range 823 to 923 K contributed to a decrease in heat capacity, as compared to the normalised and tempered sample. The martensite microstructure is found to possess the lowest room temperature CP among different microstructures.

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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