Thermally Stable Second-Order Nonlinear Optical Addition-Type Polyimides Functionalized by Diamine Chromophore

摘要

A series of chromophore-functionalized polyimide prepolymers with excellent processibility were prepared by a Michael addition reaction of diamine chromophore 2 with structurally different bismaleimide (BMI) monomers. The effects of the BMI moiety's structure and thermal curing condition on glass transition temperature (T_g) and thermal stability of the polyimides were studied by DSC, TGA, and FTIR. Among the five cured polyimides, PI_3, bearing a sulfone moiety, exhibited the highest T_g and thermal decomposition temperature (T_d). Its corresponding prepolymer, PP_3, was selected to evaluate NLO properties in a simultaneously poling and thermal polymerization process. A relatively large poling-order parameter was observed. The second-order nonlinear coefficient, d_(33), was 25 pm/V at 1064 nm fundamental wave-length. The second harmonic generation signal was almost without decay up to 170 deg C.