MEMORY EFFECTS ABOVE T-G IN POLED GUEST HOST POLYMERS/

We present systematic experiments of electric field poling and relaxat ion of 4-(dimethyl amino)-4'-nitrostilbene doped at 1 wt % in poly(iso butyl methacrylate) in a sandwich configuration of ITO electrodes usin g the second harmonic generation technique. A novel ultraslow relaxati on mode at temperatures far above the glass transition temperature T-g has been identified qualitatively with a special repoling technique. Isothermal alignment and relaxation of the chromophore orientations sh ow significant differences in their mean rates and in their sensitivit y to variations of the field strength and the presence of small amount s of plasticizer molecules. A tentative qualitative model is proposed in which the necessity for considering nonlinear responses is postulat ed.