EXCEPTIONALLY THERMALLY STABLE POLYIMIDES FOR 2ND-ORDER NONLINEAR-OPTICAL APPLICATIONS

The thermal stability of the electric field induced poled order in a n ew class of second-order optically nonlinear polymers, ''donor-imbedde d'' side-chain polyimides containing no flexible connectors or tethers to the nonlinear optical (NLO) chromophore, is investigated. In these polymers, the electron-donor part of the chromophore is a diaryl-subs tituted amine that is incorporated as a part of the polymer backbone. The donor-imbedded systems used in this study have exceptional chemica l stabilities at elevated temperatures (350 degrees C) and impressive poled order stability at extremely high temperatures (300 degrees C). In both respects, they were significantly more stable than a true side -chain polyimide with a similar NLO-active chromophore covalently link ed to the polymer backbone by a flexible tether group.