Thermotropic liquid crystalline polymers, 9. Proton magnetic resonance study of orientation of liquid‐crystalline comb‐shaped polymers in a magnetic field

Abstract

In the last few years essential success in the field of synthesis and study of a new type of polymeric compounds - thermotropic liquid-crystalline (LC) polymers has been achieved's2). However, rather little attention has been devoted to the study of the physical properties and especially the orientational ordering of polymeric mesophases. The important information about the structure and orientational order of LC polymers can be obtained from a detailed study of orientational phenomena in a magnetic field. The possibility of orientation of LC polymers with mesogenic backbone chains in a magnetic field was demonstrated recently by Blumstein et al. and Noel et al.4). Ringsdorf et a1.5) reported about a magnetically oriented mesophase of LC comb-like polymers, containing the deuterosubstituted phenyl esters of p-hydroxybenzoic acid as mesogenic groups. The authors5) made their observations on the NMR spectrum of the deuterium nuclei of the polymer mesophase. The purpose of the present paper is a proton magnetic resonance ('H NMR) study of the orientation in a magnetic field of thermotropic LC polymers, with nitrilobiphenyl mesogenic side groups.