A STUDY OF LC DIRECTOR DYNAMICS IN AN ORI ENTED CROSS-LINKED LIQUID-CRYSTALLINE POLYMER

A method for preparation of oriented cross-linked LC polyacrylates is suggested by gamma-irradiation of LC polyacrylates, preliminarily orie nted in a magnetic field. Wide-band H NMR spectroscopy was used to exa mine the dynamics of director orientation in the samples. At small gam ma-irradiation doses, the experimentally observed kinetics of LC direc tor reorientation is described within the framework of the monodomain model; both the characteristic time of LC director reorientation and r otational viscosity increased with an increase in exposure time to gam ma-irradiation until the onset of network formation. Formation of a sp atial network within the entire sample of an oriented LC polymer resul ts in the loss of orientational mobility of the mesophase in the magne tic field (the LC director does not realign in the magnetic field); th e oriented cross-linked polymer retains the orientational structure th at existed in the polymer before cross-linking.