W. Wu et al., Thermally stable nonlinear optical polyimide functionalized by N,N-diallylamino-substituted chromophore, J APPL POLY, 77(13), 2000, pp. 2939-2947
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.