Abstract
AbstractPolyesters were prepared from 4,4′‐dihydroxybiphenyl and various aryloxyterephthalic acids or various disubstituted terephthalic acids. The aryloxyterephthalic acids were prepared by nucleophilic substitution of dimethyl nitroterephthalate with phenoxide ions. The disubstituted terephthalic acids were synthesized by double alkylation of diethyl 2,5‐dihydroxyterephthalate with various alkyl bromides containing aromatic rings in the ω‐position. The silyl method was primarily used for the polycondensation procedure. The resulting polyesters were characterized by elemental analyses, viscosity measurements, wide‐angle X‐ray scattering and differential scanning calorimetry measurements, and by optical microscopy. All polyesters proved to be semicrystalline, meltable materials forming a nematic phase above their melting points. The substituents of terephthalic acid enhance the solubility in organic solvents, so that all polyesters are soluble in CH2Cl2/trifluoroacetic acid mixtures and some of them even in hot N,N‐dimethyl‐formamide or methyl benzoate.
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