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Low-Melting Nematic Quasi-Rigid Rod-Like Polyesters by Maged A. Osman is a Materials Science article available to read on EtoBox.

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## Abstract Thermotropic quasi‐rigid rod‐like polyesters with broad nematic phases in temperature ranges that allow melt processing in the mesophase have been synthesized. The desired mesomorphic temperature range can be realized by adjusting the chain flexibility and packing density as well as the axial ratio of the mesogenic segments. The chain flexibility was slightly increased without giving the molecule much conformational freedom by introducing ethylene or dioxyethylene linkages between the phenyl groups of the aromatic polyester (preferably in the acid part of the molecule). The sensitive balance between the axial ratio of the mesogenic segments and the chain flexibility was preserved to retain the mesogeneity of the molecule. Replacing some of the planar aromatic phenyl groups by staggered __trans__‐cyclohexyl moieties effectively depresses __T__~m~ without affecting __T__~i~. The effect of symmetrical and asymmetrical lateral substitution with alkyl groups of different van der Waals volume on __T__~m~ and __T__~i~ was studied. Asymmetric lateral substitution is quite effective in depressing __T__~m~ with little effect on __T__~i~. Combinations of these structural modificat

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Author

Maged A. Osman

Publisher

John Wiley and Sons; Wiley (John Wiley & Sons); John Wiley & Sons Ltd.; Wiley (ISSN 1022-1352)

Published

2007

Language

EN

Field

Materials Science (Physical Sciences)