SECOND-ORDER NONLINEAR OPTICAL POLYIMIDES WITH HIGH THERMAL STABILITY

Two high Tg (250°C and 258°C) polyimides embedded with triphenyl imidazole chromophores were synthesized through addition polymerization. Simultaneous poling and polymerization and in situ second harmonic generation measurement technology were carried on to evaluate the thermal stability of the poling induced orientations. Moderate d33 values of 15 pm/V and 16 pm/V were determined. The SHG signals of these poled polymer films are without any decay at temperature lower than 150°C, it begins to relax rapidly over 195°C. The half-decay temperatures of the samples' orientation are as high as 240°C and 24°C respectively.