Electro-optic Properties of Siloxane Based Liquid Crystal Polymers
Khalid Al-Ammar Bahaa H.Saleh Ali Razzaq
Babylon University-College of Education-Physics Department
Abstract
ِA series of siloxane based side chain liquid crystal polymers have been prepared with a systematic variation in spacer length. All the polymer exhibited a smectic phase, for which the smectic-isotropic transition temperature increased as the spacer length increased. Infrared dichroism and x-ray scattering procedures have been utilized to determine the orientational order parameters for this series of polymers and these are related to the measured electrooptical properties. It is found that with increasing spacer length (n) of polymer the threshold voltage is lowered with a functional from of n-2 and that the variation of the threshold voltage arises from changes to the intrinsic curvature elasticity rather than to differences in orientational order.
A simple model is used to indicate the origion of the effects observed which appear to arise from the constraints offered by the coupling of the mesogenic units to the polymer backbone.