Azo-functionalized hyperbranched poly(aryleneethynylene)s (hb-PAEs) (4 and 5) are synthesized by palladium-catalyzed coupling of triiodoarenes (1 and 2) with a diethynylazobenzene (3). The hb-PAEs are soluble, film-forming, and morphologically stable (T g > 180 °C). Their poled films exhibit high second-harmonic-generation coefficients (d 33 up to 177 pm/V) thanks to the chromophore-separation and site-isolation effects of hyperbranched architectural structure of the polymers in the three-dimensional space. The optical nonlinearities of the poled films are thermally stable (no drop in d 33 when heated to 152 °C) due to the facile cross-linking of the multiple acetylenic triple bonds in the hb-PAEs at moderate temperatures (down to 88 °C).

N, N-Dimethylformamide (DMF) was dried over and distilled from CaH 2 under an atmosphere of dry nitrogen. Tetrahydrofuran (THF) was dried over and distilled from K-Na alloy under an atmosphere of dry nitrogen. 2, 4-Toluenediisocyanate (TDI) was purified by distillation under reduced pressure before use. All other reagents were used as received. 1-Azido-hexane (S13) was prepared through the reaction between 1-bromohexane and sodium azide in acetonitrile at 80 o C, while azidomethyl-benzene