Effect of pyridazine structure on thin‐film polymerization and phase behavior of thermotropic liquid crystalline copolyesters

Teoh, May May; Liu, Songlin; Chung, Tai‐Shung

doi:10.1002/polb.20509

Cited by 7 publications

(13 citation statements)

References 31 publications

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“…The effect of pyridazine structure on phase behaviour of thermotropic liquid crystalline copolyesters has been studied by Teoh et al (Scheme 35). 75 Authors have carried out the effects of maleic hydrazine (MH) and hydroquinone (HQ) on the liquid crystallinity and phase transition behaviour in the ABA/HQ/ TFTA 168 and ABA/MH/TFTA 167 copolyesters (p-acetoxybenzoic acid (ABA) and tetrafluoroterephthalic acid (TFTA)) prepared by thin film polymerization. It has been demonstrated that the system 167 is energetically more favourable to mesophase formation than the system 168.…”

Section: Liquid Crystalsmentioning

confidence: 99%

Incorporation of pyridazine rings in the structure of functionalized π-conjugated materials

2011

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International audienceThroughout the past few decades, the development of new π-conjugated organic compounds has received a lot of attention due to their potential applications ranging from liquid crystals, light-emitting and nonlinear optical applications to self-assembly and supramolecular chemistry. Most of these applications rely on electron transfer (ET) and excitation energy transfer (EET). Introduction in these conjugated structures of N-heterocycles such as the highly electronegative pyridazine ring appeared particularly interesting since the π-deficient character of the pyridazine, used as a dipolar moiety, favored the electron transfer. Moreover, the presence of nitrogen atoms with free electron pairs allows the pyridazine ring to act like as an effective and stable complexing agent for transition metal ions and to be used in supramolecular chemistry for the construction of highly sophisticated architectures. This review highlights recent π-conjugated materials including pyridazine ring and their applications in various fields

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Section: Liquid Crystalsmentioning

confidence: 99%

Incorporation of pyridazine rings in the structure of functionalized π-conjugated materials

2011

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“…To date, four experimental methods have been developed to investigate the molecular director around disclination of LCPs: surface microcracks decoration, − band-texture decoration, − lamellar decoration, − and focal−conic texture decoration. , The surface microcrack, band-texture decoration, and lamellar decorations were reviewed by Qian et al in 1995, while focal−conic texture decoration was discovered only in 2000.…”

Section: Introductionmentioning

confidence: 99%

Surface Microcracks Decoration and Disclination Defects of Wholly Aromatic Liquid Crystalline Copolyesters

2006

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An intensive study has been conducted to map the director fields of disclination of nematic liquid crystalline copolyesters. In this study, films of two wholly aromatic main-chain polyesters containing para- (ABA/MH/TFTA) and meta-linkages (ABA/MH/TFIA) (ABA, p-acetoxybenzoic acid; MH, maleic hydrazine; TFTA, tetrafluoroterephthalic acid; TFIA, tetrafluoroisophthalic acid) were synthesized to investigate the effects of kinks on liquid crystallinity, disclination strength (S), and surface microcracks decoration. These two copolyesters were prepared by in-situ thin film polymerization and characterized by polarizing light microscope, wide-angle X-ray diffraction, as well as "rotational isomeric states" (RIS) Metropolis Monte Carlo (RMMC) simulation. An optical microscope shows that the surface microcracks forms in the nematic-mosaic texture during a rapid quenching. The ABA/MH/TFTA film exhibits disclination strength with S = +1 and S = -(1)/(2); however, disclination strengths with S = +/-1 have been observed in the ABA/MH/TFIA system. To our best knowledge, this is the first paper reporting the effects and evidence of kink (meta and para moieties) on topological defect of disclination. In addition, the RMMC analysis supports the liquid crystal formation in both polyester films with a persistence ratio greater than 6.42.

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“…This can be explained by the fact that pyridazine rings change the planarity of the polymer structure, which will then strongly disturb the chain packing, compared with the linear, aliphatic butane diol chain extender. Therefore, pyridazine heterocyclic ring interrupts the chain orientation and eventually inhibits the regular chain packing of the crystallization process 19. In general, DHPyd based‐PUs exhibit good mechanical properties due to the cumulative effect of the formation quite a few of hydrogen bonds and the stiffness provided by the heterocyclic rings.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, pyridazine heterocyclic ring interrupts the chain orientation and eventually inhibits the regular chain packing of the crystallization process. 19 In general, DHPyd based-PUs exhibit good mechanical properties due to the cumulative effect of the formation quite a few of hydrogen bonds and the stiffness provided by the heterocyclic rings.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

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Effect of pyridazine content and crosslinker structure on the properties of polyurethane elastomers

Oprea¹

2012

J of Applied Polymer Sci

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This article studies the development of a series of heterocyclic polyurethanes (PUs) with various pyridazine content and different crosslinker structure in their main chains. All of the isocyanate-terminated PU prepolymers were prepared from poly(tetramethylene oxide) glycol of molecular weight 1400 (Terathane 1400) and 1,6-hexamethylene diisocyanate. The properties of the obtained linear and crosslinked pyridazine-based PU were compared with the properties of common PUs obtained by chain extension with 1,4-butanediol. All the obtained PUs were characterized through spectral and thermal behavior. The pyridazine-based PU showed improved thermal stability with 10% weight loss at temperatures above 370-400 C. With the increase of pyridazine content the values of Young's modulus are higher and the strain at break decreases. Increasing pyridazine content leads to increased films surface hydrophilicity.

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Effect of pyridazine structure on thin‐film polymerization and phase behavior of thermotropic liquid crystalline copolyesters

Cited by 7 publications

References 31 publications

Incorporation of pyridazine rings in the structure of functionalized π-conjugated materials

Incorporation of pyridazine rings in the structure of functionalized π-conjugated materials

Surface Microcracks Decoration and Disclination Defects of Wholly Aromatic Liquid Crystalline Copolyesters

Effect of pyridazine content and crosslinker structure on the properties of polyurethane elastomers

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