Dielectric relaxation of poled polymer DCNP/PMMA

We have prepared the polymer thin films of a 3-(1,1-dicyanothenyl)-1-phenyl -4,5-dihydro-1H-pyrazole (DChTP)/poly (methyl methacrylate) (PMMA) guest-ho st system by spin coating. In order to investigate their temporal and tempe rature stability, we have measured their dielectric relaxation spectra incl uding the frequency dependence of the real and imaginary parts of dielectri c constants. The investigated frequency ranged from 50 Hz to 10 MHz. The me asured temperature range above the glass transition temperature T-g (95 deg rees C) of the DCNP/PMMA system was from 95 degrees C to 1250C. By using th e Adam-Gibbs model, the temperature dependence of the characteristic time t au above T-g was fitted, and the values of the characteristic times tau bel ow T-g were estimated. The lifetimes of the polymer were evaluated by the K ohlrausch-Williams Watts (KWW) empirical decay model. (C) 2000 Elsevier Sci ence B.V. All rights reserved.