Design of new Schiff base polymers containing thiadiazole rings and study of their liquid crystalline behavior

2019 ◽  
Vol 28 (2) ◽  
pp. 100-111
Author(s):  
Omer Y Thayee Al-Janabi ◽  
Ahmed K Hussein ◽  
Emaad T Bakir Al-Tikrity ◽  
Osamah A Hussein ◽  
Hana’a K Salih
Keyword(s):  
Potassium Salt ◽  
Liquid Crystalline ◽  
Condensation Reaction ◽  
Proton Nuclear Magnetic Resonance ◽  
Scanning Calorimetry ◽  
Aromatic Diamines ◽  
Polarized Optical Microscopy ◽  
Chemical Structures ◽  
Smectic Mesophase ◽  
Schiff Base Polymers

New liquid crystalline thiadiazole dibenzaldehyde monomers labeled as THDB1–THDB3 were successfully synthesized by alkylation of thiadiazole’s potassium salt with 4-(bromomethyl) benzaldehyde. A number of polymers consisting of thiadiazole and azomethine coded PTDAZ1–PTDAZ5 were synthesized via condensation reaction of the presynthesized monomers THDB1–THDB3 with aromatic diamines. The chemical structures of the prepared materials were confirmed using Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance techniques. The liquid crystalline behavior of the studied monomers and polymers was examined by differential scanning calorimetry and hot stage polarized optical microscopy (POM) techniques. All these compounds were found to demonstrate mesomorphic transitions belonging to smectic and nematic liquid crystals. The studied monomers exhibited fan-like texture of smectic mesophase under POM cooling investigation. Fan-like texture of smectic and nematic mesophases was observed under POM for PTDAZ1 and PTDAZ2, while PTDAZ3 and PTDAZ4 revealed clay and schlieren textures of the smectic and nematic mesophases, respectively, and nematic texture has been found for the polymer PTDAZ5.

Chiral Liquid Crystal Polymers Containing Electron Donor- Acceptor Action-Synthesis and Characterization

2011 ◽  
Vol 284-286 ◽  
pp. 2284-2287
Author(s):  
Xiao Zhi He ◽  
Mei Tian ◽  
Yang Chen ◽  
Jing Zhao ◽  
Bao Yan Zhang
Keyword(s):  
Electron Donor ◽  
Liquid Crystalline ◽  
Proton Nuclear Magnetic Resonance ◽  
Liquid Crystal Polymers ◽  
Scanning Calorimetry ◽  
Cholesteric Phase ◽  
Chemical Structures ◽  
Heating And Cooling ◽  
Acceptor Group ◽  
Donor Acceptor

A series of new chiral side-chain liquid crystalline polymers with electron donor-acceptor action were prepared containing chiral monomer with donor group and nematic LC monomer with acceptor group. All polymers were synthesized by graft polymerization using polymethylhydro- siloxane as backbone. The mesomorphic properties were investigated by differential scanning calorimetry(DSC), polarizing optical microscopy(POM)，thermogravimetric analyses（TGA） and X-ray diffraction measurements(XRD). The chemical structures of monomers and polymers were confirmed by Fourier transform infrared (FTIR), proton nuclear magnetic resonance spectra(1H NMR and 13CNMR). M1 showed nematic phase and M2 turned out cholesteric phase on heating and cooling cycle. Polymers P3~P8 were cholesteric phase. Experimental results demonstrated that the glass transition temperatures and isotropization temperatures and the ranges of the mesophase temperature increased with increasing the content of chiral agent. All of the obtained polymers showed high thermal stability.

Effect of Two Diferrent Mesogens on Liquid-Crystalline Properties of Chiral Side-Chain Liquid-Crystalline Polysiloxanes

2011 ◽  
Vol 415-417 ◽  
pp. 1395-1398
Author(s):  
Ji Wei Wang ◽  
Jun Qing Zi ◽  
Li Xian He ◽  
Guang Yong Chen ◽  
Yan Zhong Yang
Keyword(s):  
Liquid Crystalline ◽  
Proton Nuclear Magnetic Resonance ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Cholesteric Phase ◽  
Long Wavelength ◽  
Crystalline Polymers ◽  
Chemical Structures ◽  
Nuclear Magnetic Resonance Spectra ◽  
Temperature Ranges

Abstract. A series of liquid crystalline polysiloxanes were synthesized by cholesteric LC monomer and nematic LC monomer. The chemical structures and liquid-crystalline properties of the monomers and polymers were characterized by various experimental techniques including Fourier transform infrared (FTIR), proton nuclear magnetic resonance spectra (1H-NMR), differential scanning calorimetry (DSC), thermogravimetric analyses (TGA) , X-ray diffraction measurements (XRD) and polarizing optical microscopy (POM). All the liquid crystalline polymers showed liquid crystalline properties with wide mesophase temperature ranges. For the polymers bearing only of one nematic LC monomer, it showed nematic phase, while others showed cholesteric phase. With increase the content of nematic LC monomer in the polymers from P1 to P7, the glass transition temperature and the isotropic temperature increased on heating circles. Reflection spectra of cholesteric mesophase of the series of polymers showed that the reflected wavelength shifted to long wavelength with increase content of nematic LC monomer in the polymers in the polymer systems, suggesting that helical pitch (P) become long.

scholarly journals Discotic Liquid Crystals Based on Cu(I) Complexes with Benzoylthiourea Derivatives Containing a Perfluoroalkyl Chain

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Monica Iliş ◽  
Viorel Cîrcu
Keyword(s):  
Liquid Crystalline ◽  
Large Temperature ◽  
Discotic Liquid Crystals ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
X Ray ◽  
Ir And Nmr Spectroscopy ◽  
Hexagonal Columnar ◽  
Mesomorphic Properties

Mesomorphic three-coordinate copper(I) complexes ([Cu(BTU)2X], where X = Cl or Br) based on a new N-benzoylthiourea (BTU) ligand with two decyloxy and one perfluorooctyl groups at its periphery were designed and prepared. The BTU ligand coordinates via the S atom in a neutral monodentate fashion as confirmed by IR and NMR spectroscopy data. The liquid crystalline behavior of these copper(I) complexes was investigated by a combination of polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction analysis (XRD), while their thermal stability was studied by thermogravimetric analysis (TGA). These new copper(I) complexes have mesomorphic properties and exhibit a hexagonal columnar mesophase over a large temperature range, more than 100°C.

Azomethine ether-based potential curing agent for epoxy resin (diglycidyl ether of bisphenol A): Synthesis and characterization

2020 ◽  
pp. 009524432092857
Author(s):  
Fozia Noreen ◽  
Ahtaram Bibi ◽  
Naila Khalid ◽  
Imran Ullah Khan
Keyword(s):  
Spectral Analysis ◽  
Bisphenol A ◽  
Light Emission ◽  
Condensation Reaction ◽  
Stokes Shift ◽  
Green Light ◽  
Diglycidyl Ether ◽  
Proton Nuclear Magnetic Resonance ◽  
Curing Agent ◽  
Scanning Calorimetry

Novel azomethine ether-based compounds (A: N-((4-(9-(4-(phenylimino)methyl)phenoxy)nonyloxy)benzylidene)bezenamine and B: N-((4-(9-(4-(p-hydroxyphenylimino)methyl)phenoxy)nonyloxy)benzylidene)-4-hydroxybenzenamine) were synthesized by condensation reaction of dialdehyde, 4,4-(1,9-nonandiyle)bis(oxy)dibenzaldehyde with aromatic amines. Structures of synthesized compounds were successfully characterized by Fourier transform infrared (FTIR), ultraviolet–visible, proton nuclear magnetic resonance imaging and photoluminescence (PL) spectroscopy. The PL spectral analysis revealed that emission maxima of compounds A and B are at 475 and 500 nm, respectively, indicate blue and green light emission with large Stokes shift range (Δ λ ST, 109–138 nm). Two series of polymers: one azomethine-based polymers (C1–C5) and other without azomethine (H1–H4) were prepared by curing diglycidyl ether of bisphenol A with a synthesized curing agent (B) and commercial curing agent, respectively, in various proportions. The structural characterization of the resulting polymers was carried out by FTIR spectral analysis. Thermal properties revealed that azomethine-based polymers (C1–C5) were thermally stable up to 400°C as compared to H1–H4. The glass transition temperature of the polymers, determined by differential scanning calorimetry, was in the range 121–123°C.

Activation Energies of Liquid Crystalline Thermoset Containing Rigid-Rod Epoxy

2011 ◽  
Vol 378-379 ◽  
pp. 628-631 ◽  
Author(s):  
Seung Hwan Byun ◽  
Seung Hyun Cho
Keyword(s):  
Differential Scanning Calorimetry ◽  
Weight Loss ◽  
Thermogravimetric Analysis ◽  
Liquid Crystalline ◽  
Activation Energies ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
Rigid Rod ◽  
Liquid Crystalline Thermoset ◽  
Weight Loss Process

4,4’-Diglycidyloxy-α-methylstilbene (DOMS) was synthesized and characterized with cross-polarized optical microscopy (POM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Activation energies for decomposition (Ed) by TGA were determined as a function of conversion by weight loss process.

Synthesis and phase behavior of chiral liquid crystalline polymeric networks derived from menthol

2012 ◽  
Vol 24 (8) ◽  
pp. 673-682 ◽  
Author(s):  
Ying-Gang Jia ◽  
Jian-She Hu ◽  
Dan Li ◽  
Qing-Bao Meng ◽  
Xia Zhang
Keyword(s):  
Phase Behavior ◽  
Near Infrared ◽  
Polymer Networks ◽  
Crosslinking Agent ◽  
Proton Nuclear Magnetic Resonance ◽  
Scanning Calorimetry ◽  
Excellent Thermal Stability ◽  
Cholesteric Phase ◽  
Temperature Range ◽  
Chemical Structures

The synthesis of new chiral monomer 4-(menthyloxyacetoxy- benzoyloxy)biphenyl-4′-(2-(undec-10-e noyloxy)ethoxy)benzoate (ML), crosslinking agent 4-(undec-10-enoyloxy)biphenyl-4′-(2-(undec-10-enoyloxy)ethoxy)benzoate (CA), and liquid crystal polymer networks (E1−E5) containing menthyl group is presented. Their chemical structures and phase behavior were characterized with Fourier transform infrared (FT-IR), proton nuclear magnetic resonance (1H-NMR), elemental analyses, polarizing optical microscopy, differential scanning calorimetry, thermogravimetric analysis (TGA), and X-ray diffraction. The selective reflection of light for ML was investigated with ultraviolet/visible/near infrared (UV/Visible/NIR). By inserting a flexible spacer between the mesogenic core and the terminal menthyl groups, MLcould form mesophase and show a chiral smectic C phase, cholesteric phase and cubic blue phase. CA displayed a smectic A phase and nematic phase. The polymer networks containing less than 12 mol% of the crosslinking units showed reversible cholesteric phase transition, wide mesophase temperature range, and excellent thermal stability. With increasing the content of crosslinking unit, the corresponding Tg increased, the Ti decreased, and the mesophase temperature range narrowed for E1−E5. TGA showed that the Td(5%) was greater than 330°C for E1−E5.

Novel amino-containing fluorene-based bisphthalonitrile compounds with flexible group

2017 ◽  
Vol 30 (7) ◽  
pp. 767-775 ◽  
Author(s):  
An-ran Wang ◽  
Abdul Qadeer Dayo ◽  
Dan Lv ◽  
Yi-le Xu ◽  
Jun Wang ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Mechanical Analysis ◽  
Proton Nuclear Magnetic Resonance ◽  
Scanning Calorimetry ◽  
Rheological Analysis ◽  
Chemical Structures ◽  
The Fourier Transform ◽  
Alkoxy Groups ◽  
Nuclear Magnetic

A series of amino-containing fluorene-based bisphthalonitrile (AFPN) monomers with alkyl or alkoxy groups were successfully produced by the reaction of 4-nitrophthalonitrile with 9, 9-bis (3-alkyl (or alkoxy)-4-aminophenyl)-2, 7-dihydroxylfluorene in the presence of potassium carbonate by a nucleophilic substitution reaction. The chemical structures of the synthesized monomers were confirmed by the Fourier transform infrared (FTIR), proton nuclear magnetic resonance, and carbon-13 nuclear magnetic resonance analyses. The synthesized monomers’ curing behaviors were evaluated by FTIR and differential scanning calorimetry, and a rheological analysis was performed to evaluate their respective processabilities. Moreover, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were performed for the thermomechanical, thermal, and thermo-oxidative analyses of the polymers. The results confirmed that the newly prepared phthalonitrile (PN) monomers with alkyl or alkoxy groups exhibited a self-promoted curing behavior. The rheological analysis suggested that the processing windows of the synthesized monomers were wider than that of APFN monomer bearing no flexible group. DMA and TGA revealed that the cured polymers exhibited high glass transition temperature (358–416°C) and the char yields at 800°C under nitrogen were between 70% and 77%. Moreover, the introduction of alkyl or alkoxy groups into the PN monomers’ backbones slightly reduced the thermal stability of the resulting polymers.

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 Properties of Side Chain Azobenzene Liquid Crystalline Polymers

2013 ◽  
Vol 781-784 ◽  
pp. 436-439
Author(s):  
Dan Shu Yao ◽  
Jun He ◽  
Hai Yan Wang ◽  
Mei Tian ◽  
Xiao Zhi He ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Graft Polymerization ◽  
Liquid Crystalline Polymers ◽  
Side Chain ◽  
Scanning Calorimetry ◽  
Crystalline Polymers ◽  
Chemical Structures ◽  
Thermogravimetric Analyzer ◽  
Temperature Ranges ◽  
Mesomorphic Properties

A series of new azobenzene side chain liquid crystalline polymers were synthesized by two different azo mesogen monomers, 4-((4-(ethoxycarbonyl) phenyl) diazenyl) phenyl 4-(allyloxy) benzoate (M1) and (4-((4-(ethoxycarbonyl) phenyl) diazenyl) phenoxy) methyl acetyl 4-(allyloxy) benzoate (M2). All polymers (P1~P8) were synthesized by graft polymerization using polymethyl hydrosiloxane as backbone. Their chemical structures were confirmed by FTIR and 1HNMR spectra. The mesomorphic properties and phase behavior were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and thermogravimetric analyzer (TG) measurements. The results showed that P1~P8 exhibited thermotropic liquid crystalline properties and revealed nematic thread texture with wide mesophase temperature ranges. The temperatures when 5% weight loss occurred were higher than 305°C, which declared that the synthesized azobenzene liquid crystalline polymers had a high thermal stability.

scholarly journals Novel banana-discotic hybrid architectures

2009 ◽  
Vol 5 ◽  
Author(s):  
Hari Krishna Bisoyi ◽  
H T Srinivasa ◽  
Sandeep Kumar
Keyword(s):  
Differential Scanning Calorimetry ◽  
Optical Microscopy ◽  
Elemental Analysis ◽  
Liquid Crystalline ◽  
Scanning Calorimetry ◽  
Spectral Techniques ◽  
Design And Synthesis ◽  
Chemical Structures ◽  
Crystalline Property ◽  
Liquid Crystalline Property

Here we present the design and synthesis of novel banana-discotic dimers and banana-bridged discotic dimers. The chemical structures have been characterized by spectral techniques and elemental analysis. The thermal behaviors of the compounds have been investigated by polarizing optical microscopy and differential scanning calorimetry. None of these synthesized compounds exhibit any liquid crystalline property probably because of the incompatibility of the bent-core with the discotic core.

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