Thermally stable second-order nonlinear optical addition-type polyimides functionalized by diamine chromophore

A series of chromophore-functionalized polyimide prepolymers with excellent processibility were prepared by a Michael addition reaction of diamine chr omophore 2 with structurally different bismaleimide (BMI) monomers. The eff ects of the BMI moiety's structure and thermal curing condition on glass tr ansition temperature (T-g) and thermal stability of the polyimides were stu died by DSC, TCA, and FTIR. Among the five cured polyimides, PI3, bearing a sulfone moiety, exhibited the highest T-g and thermal decomposition temper ature (T-d). Its corresponding prepolymer, PP3, was selected to evaluate NL O properties in a simultaneously poling and thermal polymerization process. A relatively large poling-order parameter was observed. The second-order n onlincar coefficient, d(33), was 25 pmN at 1061 nm fundamental wavelength. The second harmonic generation signal was almost without decay up to 170 de grees C. (C) 1999 John Wiley & Sons, Inc.