Polymers with mesogenic elements in the main chain: A nematic aromatic copolyester

Noël, Claudine; Friedrich, Claude; Lauprêtre, F.; Billard, J.; Bosio, L.; Strazielle, C.

doi:10.1016/0032-3861(84)90335-5

Cited by 75 publications

(15 citation statements)

References 34 publications

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“…The disclination strength of such a shreaded texture was +1. Similar observation had been previuosly reported by Milland et al [ 18] for lyotropic poly(azomethines) and Noel et al [19] for a thermotropic copolyester based on methylhydroquinone, pyrocatechol, and terephthalic acid.…”

Section: Direct Observations Of Mesophasessupporting

confidence: 68%

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Liquid crystal polyarylates containing 2,6-naphthalene dicarbonyl group (I): Effects of kinky monomers on thermal and anisotropic behaviors

Liu

Lee

1994

J Polym Res

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A series of copolyarylates primarily based upon 2,6-naphthalene dicarboxylic acid, hydroxybenzoic acid and 4,4'-biphenol were prepared by slurry-melt polymerization with Santotherm 66 as a heat exchange medium. The frequently used kinky monomer, resorcinol or isophthalic acid, was introduced into these copolyarylates to modify the chemical strcture. The relationship of the thermal behavior and the crystalline structures for these copolymers was studied by means of DSC and wide angle X-rays diffraction. The amount of mcorporated kinky modifier was found to produce a significant effect on the liquid crystalline phase and the melting temperature of the copolyarylates. All of these liquid crystal polymers exhibited nematic textures; shreaded and/or Schlieren type, depending upon the incorporated kinky monomer. The liquid crystal polymers modified by isophthalic acid (up to 40 mole % of 2,6-naphthalene dicarboxylic acid replaced by isophthalic acid) possessed shreaded texture however high the temperatures of the polymer melts were. The liquid crystal polymers modified by resorcinol (60 to 100 mole % of 4, 4'-biphenol replaced by resorcinol), however, would have two types of nematic textures: the shreaded texture occurred when the temperature of the polymer melt was between the melting temperature and the anisotropic transition temperature; the Schlieren texture existed when the temperature of the polymer melt was high above the anisotropic transition temperature. The Schlieren texture formed only when a liquid crystal polymer revealed good flowability and lower rigidity. The polydomain concepts could be utilized to explain the observed textures of these copolyarylates clearly.

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Section: Direct Observations Of Mesophasessupporting

confidence: 68%

“…Homeotropic texture caused by a spontaneous orientation of molecular long axes perpendicular to the glass surface [19] occurred at 350 °C as shown in Figure 1 l(a) for PNRBBA 50 % (60140). A bright texture was instantly produced from this dark blue texture by slightly pressing the cover glass ( Figure ll(b)).…”

Section: Direct Observations Of Mesophasesmentioning

confidence: 97%

Liquid crystal polyarylates containing 2,6-naphthalene dicarbonyl group (I): Effects of kinky monomers on thermal and anisotropic behaviors

Liu

Lee

1994

J Polym Res

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“…ref 351). It is important to realize that the glass surfaces can have a strong effect on the orientation and structure of the LCP.…”

Section: Polymer Applicationsmentioning

confidence: 99%

Polymer applications

Sawyer¹,

Grubb²

1987

Polymer Microscopy

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“…When introducing substituents onto the aromatic backbone, the melting temperature can be lowered and solubility in common organic solvents is improved 6–10 . Substituents disrupt the packing preferences of the polyester chains, resulting in a lower degree of crystallinity and a suppression of the melting point.…”

Section: Introductionmentioning

confidence: 99%

All‐aromatic ester‐based thermosets: The effect of crosslinking in the nematic or isotropic state

Bijleveld

Dingemans

2021

J of Applied Polymer Sci

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We'll report on two series all‐aromatic main‐chain reactive oligomers that can be crosslinked in either the nematic phase or in the isotropic phase. This series is unique in that both model systems have an identical backbone geometry, comprised of hydroquinone with or without a phenyl substituent and phenyl substituted terephthalic acid. Crosslinking the oligomers (Mn of 1–9 kg/mol) via maleimide end‐groups in the nematic or isotropic phase yields networks with similar crosslink densities (Mc) and similar thermal properties. Crosslinked films exhibit high decomposition temperatures (>395°C) and amorphous thermoset films exhibit Tg's in the 141–190°C range whereas nematic thermoset films give Tg's that range from 143 to 176°C, as measured by DMTA. However, the phase type appears to have a major effect on the stress–strain behavior of the films. All films prepared by crosslinking un‐aligned nematic oligomers show poor stress–strain behavior (σ = 20–63 MPa, ε = 0.5%–5.4%), whereas crosslinking the amorphous oligomers results in films with excellent stress–strain properties (σ = 94–97 MPa, ε = 7.1%–13.3%). The superior toughness of the cured amorphous films can be attributed to the larger free volume induced by steric crowding of the phenyl substituents in the polymer repeat unit.

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Polymers with mesogenic elements in the main chain: A nematic aromatic copolyester

Cited by 75 publications

References 34 publications

Liquid crystal polyarylates containing 2,6-naphthalene dicarbonyl group (I): Effects of kinky monomers on thermal and anisotropic behaviors

Liquid crystal polyarylates containing 2,6-naphthalene dicarbonyl group (I): Effects of kinky monomers on thermal and anisotropic behaviors

Polymer applications

All‐aromatic ester‐based thermosets: The effect of crosslinking in the nematic or isotropic state

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