Polymer and Materials Science
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
New thermotropic liquid-crystalline polyesters (2-4) containing a mesogenic β-diketone segment, which can coordinate to a metal ion as bidentate ligand, were synthesized by polycondensation of a mixture of 1,6-hexanediol (x mol), 1,3-bis(p-hydroxyphenyl)-1,3-propanedione (y mol), and 4,4′-hexamethylenedioxydibenzoyl chloride (x + y mol). Homopolyester 1, prepared from 1,6-hexanediol and 4,4′-hexamethylenedioxydibenzoyl chloride, and copolyesters 2 and 3 (x/y = 0,8/0,2 and 0,5/0,5, respectively) show a nematic phase, whereas homopolyester 4, prepared from 1,3-bis(p-hydroxyphenyl)-1,3-propanedione and 4,4′-hexamethylenedioxydibenzoyl chloride, exhibits a smectic phase. The wide-angle X-ray diffraction patterns from the melt-drawn fibers prepared at mesophase temperatures suggested no orientation for 1, a monoaxial orientation and a crystalline state for 2, a monoaxial orientation and a frozen-in nematic phase for 3, and a biaxial orientation and a frozen-in smectic A phase for 4. Introduction of a transition metal (CuCl2 or NiCl2) into copolyesters 2 and 3 gave the corresponding metal-chelated thermotropic liquid-crystalline polyesters (5a-c, 6a-c, and 7a-c). Formation of a metal complex among polymer chains by introduction of a metal ion also resulted in better monoaxial orientation according to X-ray diffraction patterns. The ESR spectra of fibers of copper-containing polyesters (5a-c and 6a-c) indicated that the plane of the square planar copper complex in the polymers is oriented parallel to the fiber axis.
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