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A simple and efficient method for in situ preparation of highly stable polyimide (PI)-supported silver nanoparticles (AgNPs) was proposed. This process achieves excellent dispersion and high stability of AgNPs in the PI matrix. The formation of AgNPs in PI and the morphology evolution of PI/Ag nanocomposites were characterized by x-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy (FT-IR), and x-ray photoelectron spectra studies. The catalytic properties of these PI-supported AgNPs were investigated by monitoring the reduction of 4-nitrophenol by excess NaBH4 in water. The catalytic reaction was observed to have a pseudo first-order rate constant of 0.567 min−1 (9.45 × 10−3 s−1), which is comparable to other heterogeneous silver catalysts reported in the literature. Notably, the PI-supported AgNPs retained their relatively high catalytic activity over seven recycles with almost no leaching of catalytic species in the reaction solution. Moreover, the catalytic activity of the catalyst is still quite appreciable even after a six-month shelf-storage under room temperature. [ABSTRACT FROM AUTHOR]

High dielectric permittivity materials are much desirable in the electric industry. Filling polymer matrix with conductive powders to form percolative composites is one of the most promising methods to achieve high dielectric permittivity. However, they do not always provide high mechanical properties and thermal stability, which seriously limit their applications. In this study, we present the preparation of functional core-shell structured silver nanowires/polyimide (AgNWs/PI) hybrid film with high dielectric permittivity and low loss dielectric. The core-shell structure of AgNWs was characterized by transmission electric microscopy. The dynamical mechanical analysis showed that AgNWs/PI hybrid films had relative high dynamic mechanical properties with storage modules over 1 Gpa. Moreover, the hybrid films exhibited excellent thermal stability with 5 % weight-loss temperature above 500 °C. The dielectric properties of the carbon-coated AgNWs hybrid films were remarkably improved. The maximum dielectric permittivity of hybrid films is 126 at 10Hz, which was 39 times higher than that of pure PI matrix, while the dielectric loss of that is still remained at a low value. This study showed a new method to improve the dielectric, dynamic mechanical and thermal properties of films. [ABSTRACT FROM AUTHOR]