Thermally stable nonlinear optical polyimide functionalized by N,N-diallylamino-substituted chromophore

Thermally stable nonlinear optical (NLO) polyimide prepolymers with differe nt chromophore-loading levels were prepared through an addition reaction of bismaleimide 1 and N,N-diallylamino-substituted chromophore 2. The prepoly mers were used to prepare NLO polyimide in a simultaneously poling/curing p rocess. These prepolymers exhibited excellent film-forming quality and good solubility in low boiling-point solvents. Kinetic parameters (n, ln A, Ea) of their solidification reaction were determined by the dynamic method. Th ermal and NLO properties of the cured polyimides with various chromophore-l oading levels were studied. With increase of the chromophore-loading level, the glass transition temperature (T-g) and the thermal stability of the po lyimides decreased, but the second-order nonlinearity of the poled film inc reased. The largest d(33) coefficient obtained was 76.2 pm/V at 1064 nm. Th e SHG signal was rather stable up to 120 degrees C. (C) 2000 John Wiley & S ons, Inc.