Structure–property correlations in some nematic main–chain polyesters

Abstract
The homologous series of thermotropic nematic main-chain polyesters [graphic omitted] has been investigated. In the case of even values of n, a smectic phase appears at n= 18. An odd–even oscillation of nematic order parameters associated with the mesogen is observed near the clearing temperature, Tc. At the same time, in the vicinity of Tc, the relative order of mesogen and spacer is approximately the same for odd and even values of n. In unoriented specimens of polymer with spacer length n= 10, a layered structure develops progressively with increasing chain length, the sharpness and intensity of the SAX diffraction peak increasing with molecular weight. However, the degree of order remains that of a cybotactic nematic, based on measurements of the complex viscosity and miscibility behaviour. No SAX diffraction peak is observed with spacer length n= 7.

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