NMR Studies on Orientation of Liquid Crystals of Poly-γ-Benzyl-L-Glutamate in Magnetic Fields

Abstract

A concentrated methylene chloride solution of poly-γ-benzyl-L-glutamate is of liquid crystalline state. The solvent signal of this solution is a doublet due to magnetic dipole-dipole interactions. Separation of the doublet varies with residence time of the sample in magnetic fields, and this is attributable to the time dependence of the orientation of molecules in magnetic fields. The variation of the separation with temperature and with polymer concentration was studied. The difference between the observed separation and the value obtained from the equation for the dipole-dipole interactions is explained by considering the hindered molecular motion of the solvent molecules. The X-ray pattern of a polymer film, prepared from the liquid crystalline state in magnetic fields, shows the pattern of oriented crystals. The direction of the orientation agrees with the molecular axis of the film and also with the rotation axis of the methylene group of the solvent molecule.