H. Kricheldorf, Sven A. Thomsen
Sep 1, 1992
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0
Influential Citations
4
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Journal
Macromolecular Chemistry and Physics
Abstract
2-(4-Carboxyphenyl)benzoxazole-5-carboxylic acid was prepared from silylated 3-amino-4-hydroxybenzoic acid and methyl 4-chloroformyl-1-benzoate in an “one-pot procedure”. In addition to the free dicarboxylic acid the acid chloride was prepared and used as monomer. Polycondensations were conducted with the acetates or trimethylsilyl derivatives of phenylhydroquinone, phenylthiohydroquinone, 2,5-bis(phenylthio)hydroquinone and 4,4′-oxydiphenol. Furthermore, a copolyester containing 4-hydroxybenzoic acid was prepared. The resulting polyesters were characterized by elemental analyses, inherent viscosities, differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS) measurements and optical microscopy. The polyesters derived from monosubstituted hydroquinones and the copolyester were found to form nematic melts, whereas all other polyesters only form isotropic melts. The structure/property relationships are discussed by comparison with those of the corresponding poly(ester-imide)s.