Steric and electronic effects on mesophase stability of segmented liquid crystalline polymers with arylazomethine pendant groups

Abstract

The synthesis and thermotropic behavior are reported for a series of polyesters, 1, and its model compounds, 2, which bear a N-arylazomethine pendant group with para-substituents in order to evaluate electronic and steric effects on mesophase stability of segmented LCP with Y-shaped mesogens. Substituent effects on these polymer series and model compound series are dominated by steric effects. The results suggest that due to the conformational flexibility of the azomethine group this type of macromolecules cannot be strictly considered as Y-shaped segmented liquid crystal polymers. It was also concluded that when steric effects are predominant the mesomorphic behavior of model compounds can be used to estimate polymer nematic mesomorphic properties.