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Issue 31, 2019
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Synthesis and characterization of a nematic fully aromatic polyester based on biphenyl 3,4′-dicarboxylic acid

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Abstract

Melt acidolysis polymerization of hydroquinone with a kinked monomer, biphenyl 3,4′-bibenzoate, afforded a novel liquid crystalline polymer (LCP), poly(p-phenylene 3,4′-bibenzoate) (poly(HQ-3,4′BB)). Selection of hydroquinone diacetate (HQa) or hydroquinone dipivilate (HQp) facilitated either a tan or white final polymer, respectively. 1H NMR spectroscopy confirmed consistent polymer backbone structure for polymers synthesized with either derivative of hydroquinone. Poly(HQ-3,4′BB) exhibited the onset of weight loss at about 480 °C, similar to commercially available Vectra® LCP. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) revealed a glass transition temperature (Tg) of 190 °C and an isotropic temperature (Ti) near 330 °C. The observation of a melting temperature (Tm) depended upon the thermal history of the polymer. Wide-angle X-ray scattering (WAXS) and polarized optical microscopy (POM) confirmed the formation of a nematic glass morphology after quench-cooling from the isotropic state. Subsequent annealing at 280 °C or mechanical deformation induced crystallization of the polymer. Rheological studies demonstrated similar shear thinning behavior for poly(HQ-3,4′BB) and Vectra® RD501 in the power law region at 340 °C. Zero-shear viscosity measurements indicated that HQa afforded higher melt viscosities after identical polymerization conditions relative to HQp, suggesting higher molecular weights.

Graphical abstract: Synthesis and characterization of a nematic fully aromatic polyester based on biphenyl 3,4′-dicarboxylic acid

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Supplementary files

Article information


Submitted
11 May 2019
Accepted
19 Jun 2019
First published
23 Jun 2019

Polym. Chem., 2019,10, 4287-4296
Article type
Paper
Author version available

Synthesis and characterization of a nematic fully aromatic polyester based on biphenyl 3,4′-dicarboxylic acid

K. V. Heifferon, G. A. Spiering, S. J. Talley, M. Hegde, R. B. Moore, S. R. Turner and T. E. Long, Polym. Chem., 2019, 10, 4287
DOI: 10.1039/C9PY00683D

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