Exceptionally thermally stable polyimides for second-order nonlinear optical applications

The thermal stability of the electric field induced poled order in a new class of second-order optically nonlinear polymers, "donor-imbedded" 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-substituted amine that is incorporated as a part of the polymer backbone. The donor-imbedded systems used in this study have exceptional chemical stabilities at elevated temperatures (350°C) and impressive poled order stability at extremely high temperatures (300°C). In both respects, they were significantly more stable than a true side-chain polyimide with a similar NLO-active chromophore covalently linked to the polymer backbone by a flexible tether group.