Synthesis and nonlinear optical properties of high glass transition polyimides

Nonlinear optical (NLO) polymers with glass transition temperatures (T_g) as high as 275°C were prepared by covalent bonding of a chromophore to the backbone of hydroxyl polyimides via a Mitsunobu reaction. NLO side-chain polyimides with different polymer backbones and different chromophores were prepared and characterized by second-harmonic generation. Poled films of the polymers have an excellent nonlinear optical response that is stable at elevated temperatures.