Abstract
Semi-rigid polyesters based on twin biphenyl analogues of 1,3,4-thiadiazole (2-phenyl-1,3,4-thiadiazoles) with hepta- and octamethylene chains in the central part were synthesized by melt polycondensation of bismethyl ester derivatives of twin 2-phenyl-1,3,4-thiadiazole with α, ω-alkylenediols and dioxydialcohol derivatives of biphenyl. The relationship between polymer structure and thermotropic liquid-crystallinity (LC) was investigated by differential scanning calorimetry (DSC), polarizing microscope observations, miscibility tests and temperature-dependent X-ray analysis. All the polymers derived from α, ω-alkylenediols appeared to form enantiotropic or monotropic nematic phase independent of the lengths of aliphatic chains. Among the polyesters containing the biphenyl unit, most polymers with octamethylene segment between the twin 2-phenyl-1,3,4-thiadiazoles showed the nematic phase, but polymers composed of the twin biphenyl analogue having the central heptamethylene chain had no LC melts.
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Sato, M., Yoshinaga, T. & Koide, N. Thermotropic Liquid-Crystalline Polymers Having Five-Membered Heterocycles as Mesogens V. Relationship between Polymer Structure and Thermotropic Liquid-Crystallinity in Semi-Rigid Polyesters Composed of Twin 2-Phenyl-1,3,4-thiadiazoles Having Central Aliphatic Chains. Polym J 32, 753–759 (2000). https://doi.org/10.1295/polymj.32.753
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DOI: https://doi.org/10.1295/polymj.32.753