The determination of the order parameters and director alignment in the nematic phase of a liquid crystalline side-chain polymer by the resolution of dielectric loss spectra

Abstract

It is shown how the broad and asymmetric dielectric loss spectra obtained for a nematogenic side-chain siloxane polymer can be fitted by the superposition of two Fuoss-Kirkwood curves. The degree of director alignment and the second rank orientational order parameters of the sample are estimated by relating the intensities of the two curves to the intensities of the loss processes as given by the generalization of the Nordio-Rigatti-Segre theory to the case of arbitrary director alignment. It appears that the nematic phase of the material studied has a high degree of planar director alignment and that the order parameters are much smaller than those observed for low molar mass nematogens.