scholarly journals LIQUID CRYSTALLINE PROPERTIES OF HYDROXYPROPYL CELLULOSE PREPARED FROM DISSOLVED EGYPTIAN BAGASSE PULP

2021 ◽  
Vol 55 (1-2) ◽  
pp. 13-22
Author(s):  
ABOU-ZEID RAGAB E. ◽  
NAHLA A. EL-WAKIL ◽  
AHMED ELGENDY ◽  
YEHIA FAHMY ◽  
ALAIN DUFRESNE
Keyword(s):  
Molecular Structure ◽  
1H Nmr Spectroscopy ◽  
Liquid Crystalline ◽  
Critical Concentration ◽  
Polarized Light ◽  
Hydroxypropyl Cellulose ◽  
Scanning Calorimetry ◽  
Dimethyl Acetamide ◽  
Ft Ir ◽  
Bagasse Pulp

"Egyptian agricultural wastes were used for preparing advanced cellulosic derivatives possessing liquid crystalline properties. Cellulose was successfully isolated in pure form from Egyptian bagasse pulp. Hydroxypropylation was carried out on the obtained cellulose and the liquid crystalline properties were investigated. The prepared hydroxypropyl cellulose (HPC) was esterified with 4-alkyloxybenzoic acids, giving products with liquid crystalline properties. The molecular structure of HPC and a series of its esters – 4-alkoxybenzoloxypropyl cellulose (ABPC-m) – was confirmed by Fourier transform infrared (FT-IR) and 1H NMR spectroscopy. The liquid crystalline (LC) phases and transition behaviors were investigated using differential scanning calorimetry (DSC) and polarized light microscopy (PLM). The lyotropic behavior in dimethyl acetamide (DMA) was investigated using an Abee refractometer, and the critical concentration was determined by measuring the refractive index of the solutions in DMA."

scholarly journals Mesomorphic Behavior of Symmetric Azomethine Dimers Containing Different Chromophore Groups

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2183
Author(s):  
Elena Perju ◽  
Luminita Marin
Keyword(s):  
Aromatic Amines ◽  
1H Nmr Spectroscopy ◽  
Liquid Crystalline ◽  
Condensation Reaction ◽  
Optoelectronic Devices ◽  
Polarized Light ◽  
The Other ◽  
Scanning Calorimetry ◽  
Intense Luminescence ◽  
Photophysical Behavior

A series of new azomethine dimers was synthesized by the condensation reaction of flexible bis-benzaldehydes with four aromatic amines containing phenyl, naphthyl, anthracene and pyrene groups. Their right structure was confirmed by FTIR and 1H-NMR spectroscopy and their thermal properties were investigated by thermogravimetric analysis, differential scanning calorimetry and polarized light optical microscopy. A view on their photophysical behavior was gained by UV-vis and photoluminescence spectroscopy. The dimers containing pyrene and anthracene presented liquid crystalline behavior, while the other dimers were crystalline compounds. Two dimers containing pyrene moieties formed mesomorphic glasses and had intense luminescence, promising properties for applications in building optoelectronic devices.

Liquid crystalline polyureas with oligo(ethylene glycol) sequences

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Shahram Mehdipour-Ataei ◽  
Leila Akbarian-Feizi
Keyword(s):  
Liquid Crystalline ◽  
Spectroscopic Method ◽  
Polymerization Reaction ◽  
X Ray Diffraction ◽  
Subsequent Reaction ◽  
Scanning Calorimetry ◽  
Polar Solvents ◽  
X Ray ◽  
H Nmr ◽  
Ft Ir

AbstractA diamine monomer containing ester, amide and ether functional groups was prepared and its polymerization reaction with different diisocyanates to give main chain poly(ester amide ether urea)s was investigated. The monomer was synthesized via reaction of terephthaloyl chloride with 4-hydroxybenzoic acid and subsequent reaction of the resulted diacid with 1,8-diamino-3,6-dioxaoctane. The polymers were characterized by FT-IR and 1H-NMR spectroscopic method and elemental analysis. The resulting polymers exhibited excellent solubility in polar solvents. Crystallinity of the resulted polymers was evaluated by wide-angle X-ray diffraction (WXRD) method, and they exhibited semi-crystalline patterns. The glass transition temperatures (Tg) of the polymers determined by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) were in the range of 88-112 °C. The temperatures for 10% weight loss (T10) from their thermogravimetric analysis (TGA) curves were found to be in the range of 297-312 °C in air. Also the prepared polyureas showed liquid crystalline character.

Synthesis and Properties of Thermotropic Liquid Crystalline Polyesters with Flexible Polymethylene Spacer

2010 ◽  
Vol 428-429 ◽  
pp. 126-131
Author(s):  
Wei Zhong Lu ◽  
Chun Wei ◽  
Qui Shan Gao
Keyword(s):  
Optical Microscopy ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Structure Morphology ◽  
Temperature Ranges ◽  
Ft Ir ◽  
Diffraction Peaks ◽  
Ubbelohde Viscometer

Polymethylene bis(p-hydroxybenzoates) were prepared from methyl p-hydroxybenzoate and different diols by melted transesterification reaction. Three liquid crystalline polyesters were synthesized from terephthaloyl dichloride and polymethylene bis(p-hydroxybenzoates). Its structure, morphology and properties were characterized by Ubbelohde viscometer, Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC), polarized optical microscopy (POM) with a hot stage, and wide-angle X-ray diffraction (WAXD). Results indicated that the intrinsic viscosities were between 0.088 and 0.210 dL/g. Optical microscopy showed that the TLCP has a highly threaded liquid crystalline texture and a high birefringent schlieren texture character of nematic phase and has wider mesophase temperature ranges for all polyesters. DSC analysis were found that the melting point (Tm), isotropic temperature (Ti) of TLCPs decreased and the temperature range of the liquid crystalline phase became wider with increased number of methylene spacers in the polyester. The WAXD results showed that TLCPs owned two strong diffraction peaks at 2θ near 19° and 23°.

Thermotropic behavior of sodium cholesteryl carbonate

2009 ◽  
Vol 24 (1) ◽  
pp. 156-163 ◽  
Author(s):  
Rabkwan Chuealee ◽  
Timothy S. Wiedmann ◽  
Teerapol Srichana
Keyword(s):  
Phase Behavior ◽  
Chemical Structure ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Wave Number ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
C Nmr

Sodium cholesteryl carbonate ester (SCC) was synthesized, and its phase behavior was studied. The chemical structure was assessed by solid-state infrared spectroscopy based on vibration analysis. The wave number at 1705 and 1276 cm−1 corresponds to a carbonyl carbonate and O–C–O stretching of SCC, respectively. Molecular structure of SCC was further investigated with 1H and 13C NMR spectroscopy. The chemical shift, for the carbonyl carbonate resonance appeared at 155.5 ppm. A molecular mass of SCC was at m/z of 452. Differential scanning calorimetry (DSC), video-enhanced microscopy (VEM) together with polarized light microscopy, and small-angle x-ray scattering (SAXS) were used to characterize the phase behavior as a function of temperature of SCC. Liquid crystalline phase was formed with SCC. Based on the thermal properties and x-ray diffraction, it appears that SCC forms a structure analogous to the type II monolayer structure observed with cholesterol esters.

scholarly journals Synthesis, Mesomorphism and the Optical Properties of Alkyl-deuterated Nematogenic 4-[(2,6-difluorophenyl)ethynyl]biphenyls

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4653
Author(s):  
Jakub Herman ◽  
Piotr Harmata ◽  
Michał Czerwiński ◽  
Olga Strzeżysz ◽  
Marta Pytlarczyk ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Mass Spectrometry ◽  
Differential Scanning Calorimetry ◽  
Optical Properties ◽  
Liquid Crystalline ◽  
Near Infrared ◽  
Synthesis And Characterization ◽  
Molecular Approach ◽  
Scanning Calorimetry

The synthesis and characterization of new deuterated liquid crystal (LC) compounds based on phenyl tolane core is described in this paper. The work presents an alternative molecular approach to the conventional LC design. Correlations between molecular structure and mesomorphic and optical properties for compounds which are alkyl-hydrogen terminated and alkyl-deuterium, have been drawn. The compounds are characterized by mass spectrometry (electron ionization) analysis and infrared spectroscopy. They show enantiotropic nematic behavior in a broad temperature range, confirmed by a polarizing thermomicroscopy and differential scanning calorimetry. Detailed synthetic procedures are attached. Synthesized compounds show a significantly reduced absorption in the near-infrared (NIR) and medium-wavelength infrared (MWIR) radiation range, and stand as promising components of medium to highly birefringent liquid crystalline mixtures.

scholarly journals Mesomorphism behaviour and photoluminescent properties of new asymmetrical 1,2-di(4-alkoxybenzylidene)hydrazines

2019 ◽  
Vol 43 (1-2) ◽  
pp. 67-77 ◽  
Author(s):  
Adil A Awad ◽  
Al-Ameen Bariz OmarAli ◽  
Ahmed Jasim M Al-Karawi ◽  
Zyad Hussein J Al-Qaisi ◽  
Samer Ghanim Majeed
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Luminescent Properties ◽  
Scanning Calorimetry ◽  
Crystalline Materials ◽  
X Ray ◽  
Step Procedure ◽  
Liquid Crystalline Materials

{1-[4-( n-Alkoxy)]-2-(4’-decyloxy)benzylidene}hydrazines ( n-alkoxy = O(CH2) nH, n = 1–9, 12, 16 or 18), an asymmetrical series of 1,2-disubstituted hydrazines, were prepared in a simple two-step procedure as a part of our continuing work in evaluating hydrophobic azine compounds as photoluminescent liquid crystalline materials. The compounds were characterized spectroscopically and their liquid crystalline behaviour and luminescent properties were evaluated using polarized light optical microscopy, differential scanning calorimetry and X-ray powder diffraction techniques. The studies revealed that all of these compounds are liquid crystalline materials exhibiting photoluminescent properties in the crystalline and liquid crystal states.

Perfluoropolyether Modified Waterborne Shape Memory Polyurethaneurea Ionomers for Potential Medical Implant Application

2012 ◽  
Vol 499 ◽  
pp. 53-57
Author(s):  
Qun Xia Li ◽  
Zhong Yu Hou
Keyword(s):  
Molecular Structure ◽  
Differential Scanning Calorimetry ◽  
Transition Temperature ◽  
Shape Memory ◽  
Soft Segment ◽  
Cross Linking ◽  
Isophorone Diisocyanate ◽  
Scanning Calorimetry ◽  
Weight Percentage ◽  
Ft Ir

A series of cross-linked fluorinated waterborne shape memory polyurethaneurea (PUU) ionomers were synthesized from polycaprolactone diol, perfluoropolyether diol (PFPE), dimethylolproionic acid, isophorone diisocyanate, ethylenediamine (EDA) and diethylenetriamine (DETA). The effect of PFPE content in the soft segment and the degree of cross-linking on the molecular structure and the properties of for these PUU films was examined and studied. Differential scanning calorimetry showed that the transition temperature for these Tm type shape memory PUU could be facially tuned by PFPE weight percentage and EDA/DETA ratio in the range between 30°C to 50°C, in the vicinity of body temperature. The dependence of their properties on hydrogen-bonds evaluated by FT-IR was also discussed.

SYNTHESIS AND CHARACTERIZATION OF NEW THERMOTROPIC LIQUID CRYSTALLINE POLYURETHANES WITH BIPHENYL MOIETY

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4487-4492 ◽  
Author(s):  
JONG BACK LEE ◽  
SANG PILL LEE ◽  
JIN KYUNG LEE
Keyword(s):  
Liquid Crystalline ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Infrared Study ◽  
H Nmr ◽  
X Ray Scattering ◽  
Phase Transition Temperatures ◽  
No Weight Loss ◽  
Ft Ir ◽  
Tolylene Diisocyanate

A new series of thermotropic polyurethanes containing biphenyl units was synthesized by polyaddition reaction of diisocyanates such as 2,6-tolylene diisocyanate, 2,5-tolylene diisocyanate, 2,4-tolylene diisocyanate, and 1,4-phenylene diisocyanate, with 4,4□-bis(9-hydroxynonoxy)biphenyl (BP9). Structures of the monomer and the corresponding polymers were identified using FT-IR and 1 H NMR spectroscopic methods. BP9 exhibited a smectic type mesophase, however, nematic phase was found for all synthesized liquid crystalline polyurethanes except for 1,4-phenylene diisocyanate/BP9 based polyurethane. Their phase transition temperatures and thermal stability were investigated by differential scanning calorimetry (DSC), optical polarizing microscopy, and X-ray scattering. The infrared study indicated that the hydrogen bonding among urethane linkages attributed to the mesomorphism. Thermal gravimetric analysis (TGA) of synthesized polyurethanes showed that no weight loss of the polymers observed up to 280°C.

scholarly journals New Rod-Like H-Bonded Assembly Systems: Mesomorphic and Geometrical Aspects

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 795
Author(s):  
Laila A. Al-Mutabagani ◽  
Latifah Abdullah Alshabanah ◽  
Hoda A. Ahmed ◽  
Khulood A. Abu Al-Ola ◽  
Mohamed Hagar
Keyword(s):  
Density Functional ◽  
Polarized Light ◽  
Proton Donor ◽  
Proton Acceptor ◽  
Scanning Calorimetry ◽  
Functional Theory ◽  
Ft Ir ◽  
Ir Spectroscopic ◽  
Thermal Stability Of ◽  
Bonded Complexes

Experimental and geometrical approaches of new systems of mesomorphic 1:1 supramolecular H-bonded complexes (SMHBCs) of five rings are discussed. The H-bonding between 4-alkoxyphenylimino benzoic acids (An, as proton acceptor) and 4-(4′–pyridylazophenyl) 4′′-alkoxybenzoates (Bm, as proton donor) were investigated. Mesomorphic behaviors were analyzed by differential scanning calorimetry (DSC) and mesophase textures were identified by polarized light microscopy (POM). H-bonded assembly was established by FT-IR spectroscopic measurements via Fermi band discussion. Thermal and theoretical factors were predicted for all synthesized complexes by density functional theory (DFT) predictions. The results revealed that all prepared complexes were monomorphic, with a broad range of smectic A phases with a high thermal stability of enantiotropic mesophase. Furthermore, DFT stimulations illustrated the experimental results in terms of the influence of the chain length either of the acid or the base component. Many parameters, such as the calculated stability, the dipole moment and the polarizability of the H-bonded complexes, illustrate how these parameters work together to enhance the smectic mesophases with the obtained stability and range.

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