Die höheren Homologen der Azophenol‐, Azoxyphenol‐ und Azomethinphenoläther

Weygand, C.; Gabler, R.

doi:10.1002/prac.19401551006

Cited by 57 publications

(29 citation statements)

References 4 publications

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“…For example, aromatic acid derivatives with alkoxy or alkyl terminal groups form dimers due to hydrogen bond between their carboxylic acid groups, and show mesomorphism. [41][42][43][44] Association between different species of molecules also induces the isotropic/ anisotropic phase transition. 27,45,46 Mesophases of some liquid-crystalline molecules are stabilized by hydrogen bond with different species of molecules.…”

Section: Hydrogen-bonded Supramoleculesmentioning

confidence: 99%

Theoretical Study of Molecular Association and Thermoreversible Gelation in Polymers

Tanaka

2002

Polym J

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ABSTRACT:This paper reviews our recent theoretical studies of molecular association and thermoreversible gelation in polymer solutions and blends. We first classify fundamental types of association, and propose their static and dynamic characterization. We then develope general theory of associating polymers to study phase transitions induced by molecular association. These transitions include macro-and microphase separation, micellization, hydration, thermoreversible gelation and liquid-crystalization. As for the origin of associative forces, we focus on hydrogen bonding and hydrophobic aggregation. Detailed study on thermoreversible gelation with multiple cross-link junctions is presented. Paying special attention to the multiplicity and sequence length of the network junctions, we derive phase diagrams with coexisting gelation and phase separation, and compare them with experimental data. Local and global structures of the gel networks are studied from molecular point of view. The theory is applied to more complex thermoreversible gels such as binary networks (interpenetrating networks, alternating networks and randomely mixed networks), hydrated networks with high-temperature gelation, gelation strongly coupled to polymer conformational transitions such as coil-to-helix transition. To study dynamics of thermoreversible gels, a simple transient network model is introduced, and creation and annihilation of junctions in the networks are theoretically described. Stationary non-linear viscosity and the dynamic mechanical moduli are calculated as functions of the shear rate, frequency and the chain disengagement rate. From the peak of the loss modulus, the lifetime τ × of the junction is estimated, and from the high frequency plateau of the storage modulus, the number of elastically effective chains in the network is found. Transient phenomena such as stress relaxation and stress overshoot are also theoretically studied. Results are compared with the recent experimental reports on the rheological study of hydrophobically modified water-soluble polymers.KEY WORDS Associating Polymers / Thermoreversible Gelation / Junction Multiplicity / Multicriticality / Transient Networks / Shear Thickening / Elastically Effective Chains / This paper reviews our recent theoretical studies of molecular association and thermoreversible gelation in polymer solutions. We introduce new theoretical frameworks to study phase transitions induced by association of polymer chains and dynamics of aggregation/dissociation processes.In most polymer blends or solutions, polymer chains carry active groups interacting with each other via strongly associative forces which are capable of forming temporal bonds. Hence description of the system in terms of van der Waals type contact energy -or χ-parameter in lattice theoretical terminology -is insufficient. These associative interactions include hydrogen bonding, ionic aggregation, electrostatic interaction, micro-crystallite formation, stereocomplex formation, solvent-complex formation, etc. Since ...

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Section: Hydrogen-bonded Supramoleculesmentioning

confidence: 99%

Theoretical Study of Molecular Association and Thermoreversible Gelation in Polymers

Tanaka

2002

Polym J

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“…Das E/Z-Verhältnis ist größer als 1000:1, so ist es möglich, extrem konfigurationsreine Ver bindungen herzustellen [1], Die Aldehyde la [5] und lb [6] können durch Al kylierung von 4-Hydroxybenzaldehyd gewonnen werden. Analog werden l c [7], l d (diese Arbeit) und le [3] aus 3,4-Dihydroxybenzaldehyd herge stellt.…”

Section: Syntheseunclassified

“…175 °C. -IR (KBr): 2910 cm " 1, 28401, , 15101, , 14351, , 12601, , 1110: S = 0,85 (t, 6H , C H 3), 1,26 (m,36 H,CH,),1,60 (m,2H ,),1,70 (m,2H ,),3,50 (t,2H ,3,84 (t,2H ,),5,30 (d,2H ,CH,P),6,55" (m,3H ,arom at. H),7,80 (m,15H,.…”

Section: Synthese Von (E Z )-1 4 -B Is{2 -[ 3 4-bis-(dodecyloxy ) mentioning

confidence: 99%

Synthese, Flüssigkristallinität und Photochemie von Di- und Tristyrylbenzolen mit Alkoxyseitenketten / Synthesis, Liquid Crystals and Photochemistry of Di- and Tristyrylbenzenes with Alkoxy Side Chains

Zerban

Meier

1993

Zeitschrift Für Naturforschung B

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(7) erhal ten werden. Nach dem Schutz der Carboxygruppe durch Veresterung werden die phenolischen OH-G ruppen alkyliert (8 -* 9). Ü ber die freie Säure 10 und ihr Säurechlorid 11 gelangt man durch Rosen m und-R eduktion zum gewünschten Aldehyd lf.lg wird nach Vorschrift [7] in drei Stufen aus 3,4,5-Trihydroxybenzoesäure-ethylester her gestellt. NM R-spektroskopische Charakterisierung der stilbenoiden Verbindungen 4 und 6Die 'H -N M R -D aten von (.E ,£)-4a-g und (E,E,E)-6 a,b ,g sind in den Tab. I und II zusam mengestellt. Die schwer löslichen Verbindungen (E,E)-4a-e wurden bei erhöhter Tem peratur ge messen. Besonders charakteristisch ist das Singulett der aromatischen Protonen des zentralen Ben zolrings im Bereich 7,4 < ö < 7,5 und das olefini sche AB-System bei 6,95 ± 0,06 und 7,04 ± 0,08 mit einer vicinalen Kopplung V von 16,4 ± 0,1 Hz. Die 13C -N M R -D aten sind in den Tab. III und IV wiedergegeben.Brought to you by | MIT Libraries Authenticated Download Date | 5/11/18 3:36 AM

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“…From the optical microscopic investigations, it is observed that the pure p−n-alkyl benzoic acids [19] and OBCA [20] are enantiotropic liquid crystalline compounds exhibiting only threaded nematic mesophase (Fig. 2).…”

Section: Thermal and Phase Behaviormentioning

confidence: 99%

Induced Smectic A Phase through Intermolecular Hydrogen Bonding: Part XVIII: Influence of p-n-Alkyl Benzoic Acids on Thermal and Phase Behavior οf Hydrogen-Bonded Liquid Crystals

Vijayalakshmi

Sastry

2009

Acta Phys. Pol. A

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A novel series of intermolecular hydrogen bonded liquid crystals was synthesized with the mesogens of p-n-alkyl benzoic acids (nBA where n = 5 to 10) and p-(p -octyloxy benzylidene)-cyano aniline (OBCA) moieties. The thermal and phase behaviors of these mesogens (nBA:OBCA) are studied by thermal polarizing optical microscopy and differential scanning calorimetry techniques. Induced smectic A phase with focal conic fan texture is observed in all the synthesized compounds. Moreover, the nematic phase present in all the pure p-n-alkyl benzoic acids (nBA where n = 6 to 10) is quenched in all the hydrogen bonded compounds (nBA:OBCA) and smectic A phase is induced. But, in the compound 5BA:OBCA the nematic phase is also present along with the induced smectic A phase. The structural elucidation pertaining to the formation and stabilization of intermolecular hydrogen bonding is carried out by a detailed IR spectral investigation.

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Die höheren Homologen der Azophenol‐, Azoxyphenol‐ und Azomethinphenoläther

Cited by 57 publications

References 4 publications

Theoretical Study of Molecular Association and Thermoreversible Gelation in Polymers

Theoretical Study of Molecular Association and Thermoreversible Gelation in Polymers

Synthese, Flüssigkristallinität und Photochemie von Di- und Tristyrylbenzolen mit Alkoxyseitenketten / Synthesis, Liquid Crystals and Photochemistry of Di- and Tristyrylbenzenes with Alkoxy Side Chains

Induced Smectic A Phase through Intermolecular Hydrogen Bonding: Part XVIII: Influence of p-n-Alkyl Benzoic Acids on Thermal and Phase Behavior οf Hydrogen-Bonded Liquid Crystals

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