Structure-activity relationship of new nonlinear optical organic materials based on push-pull azo dyes. 3. Guest-host systems

Several new push-pull azobenzene dyes with different electron-withdrawing groups, steric hindrance, and hydrogen-bonding capabilities were dispersed in poly(N-methacryloyl-N'-phenylpiperazine) a glassy polymer matrix. After orientation by corona poling, the second harmonic generation (SHG) signals of the guest-host systems were measured as a function of time and temperature and fitted with Kohlrausch-Williams-Watts (KWW) stretched exponentials. The variations of their nonlinear susceptibilities at time zero and in their relaxation behavior were correlated with the changes of the chromophore chemical structure. Rigid rod structures always presented the best orientability and stability of the nonlinear optical properties.