Ultrahigh-temperature polymers for second-order nonlinear optics. Synthesis and properties of robust, processable, chromophore-embedded polyimides

A general, convergent approach to the synthesis of a series of stilbene- and ate-based donor-acceptor, second-order nonlinear optical (NLO) chromophores is reported. The synthetic strategy enables preparation of both acid- and base-reactive structures, yielding protected, diamine-functionalized chromophores which can be liberated using either acidic or alkaline regents for incorporation into polyimide backbones. Three such chromophores, bis(4-aminophenyl)[4-(2-(4-nitrophenyl)vinyl)phenyl]amine, bis(4-aminophenyl)[4-(2-(6-nitrobenzothiazol-2-yl)vinyl)phenyl]amine, 2-[4-((4-(bis(4-aminophenyl)amino)phenyl)diazenyl)phenyl]-2-phenyl-1, 1-dicyanoethylene, all having high thermal stabilites, were synthesized, characterized, and condensed with hexafluoroisopropylidene diphthalic anhydride or 2-(1,3-dioxoisolounzofuran-5-ylcarbonyloxy)ethyl 1,3-dioxoisobenzofuran-5-carboxylate to yield six high glass transition temperature polyimides (T-g as high as 313 degrees C) for use as poled NLO materials. After casting as thin films, curing, and electric field corona poling, these materials exhibit chi((2)) (1064 nm) responses as high as 82.0 pm/V and negligible decay in response upon aging in air at 100 degrees C for over 1000 h.