LINEAR AND NONLINEAR DIELECTRICITY OF POLY(METHYL METHACRYLATE) CONTAINING AZO COMPOUND IN THE SIDE-CHAIN

Dielectric properties of nonlinear optical chromophore functionalized poly(methyl methacrylate) (PMMA) with 4-amino-4'-nitroazobenzene (DO3) have been investigated in the temperature range from -180 to 150 degrees C. Four relaxation processes were found. Three of these relaxation processes were also observed in PMMA homopolymer. The four processes are respectively attributed to the relaxation due to absorbed moisture, the relaxation of the side chain without DO3 group, the primary relaxation of microphase with a low concentration of DO3 group, and the primary relaxation of microphase with a high concentration of DO3 group, in order of ascending temperature. Time dependence of the second-order dielectric constant \epsilon(2)\ for a sample obtained by poling DO3-PMMA have been measured at various temperatures. At room temperature, the decay was slight. At 60 degrees C and 110 degrees C, the values of \epsilon(2)\ after 6 h from the end of poling decayed by 30 similar to 50% of the initial values of \epsilon(2)\. Observed values at 60 degrees C and 110 degrees C was able to be described by the biexponential equation better than by KWW (Kohlrausch-Williams-Watts) equation indicating that DO3 groups exist in at least two different kinds of environment.