The Existence of Two Distinct Levels of Order in Thermotropic Nematic Polyesters
- 1 January 1983
- journal article
- research article
- Published by Taylor & Francis in Molecular Crystals and Liquid Crystals
- Vol. 92 (3), 87-97
- https://doi.org/10.1080/01406568308084524
Abstract
It is shown by means of x-ray diffraction and PMR broad line spectroscopy, that the structure of the flexible spacer drastically influences the order within the nematic phase of thermotropic polyesters based on the 4,4′ - dioxy- 2, 2′-dimethyl azoxybenzene moiety. The existence of two distinct molecular arrangements is proposed: one is characterized by an unusually high degree alignment of macromolecules, the other by a lower degree of alignment. The former is displayed by spacers with an even number of methylene units in the alkanedioic acid moiety of the spacer (odd number of bonds); the latter by a certain number of flexible spacer moieties with an odd number of methylene groups (even number of bonds), as well as in mixed spacers irregularly alternating along the macromolecular chain (copolyesters).Keywords
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