Mesophases Thermotropes de Poly(azomethlnes) A Chaines “Souples”

Abstract

The thermotropic polymorphism of poly(azomethine) of general formula: p = 1,3,6, has been studied. The combined use of gel permeation chromatography, light scattering and viscosimetry enable the determination of the molecular weight of the samples and of the coefficients K and a of the Mark-Houwink viscosity law. We showed that, in dilute solution, the chains can be considered as flexible chains with excluded volume effect. By polarized light microscopy, the existence of thermo-tropic liquid-crystalline phases has been shown. The temperature of transition between the phases depends on the length of the aliphatic part. For example, for p = 6, after the crystalline phase, a smectic phase appears at 240°C and a nematic phase at 290°C. The nematic phase was proved by observing the threaded texture.