In situ catalyzed and reinforced high-temperature flexible crosslinked ZnO nano-whisker/polyarylene ether nitriles composite dielectric films

Zinc oxide nano-whiskers (ZnO-nws) with the aspect ratio of about 30 are prepared via hydrothermal method and characterized by XRD and SEM. Then, the ZnO-nws are doped into polyarylene ether nitriles terminated with phthalonitrile (PEN-Ph) to fabricate the ZnO-nws/PEN-Ph crosslinked composite films. The crosslinking density, thermo-stability, dielectric property, microstructure and mechanical property are investigated in detail. According to the DSC test, the ZnO-nws can be served as catalyst for the crosslinking reaction of phthalonitrile. Under the same condition, the crosslinking density of the composites is determined by the weight content of ZnO-nws, and is 5.45 x 10(-2) mol/cm(3) when 4 wt% of ZnO-nws is incorporated. The TGA and DSC results show that the ZnO-nws/PEN-Ph crosslinked composite films are endowed with excellent thermo-stability and operating temperature. With the ZnO-nws incorporated, the dielectric constant of the composite is improved from 3.4 to 6.2 at 1 kHz when the ZnO-nws weight content is 16 wt%. The mechanical property test shows that the tensile strength increases with the increasing weight content of ZnO-nws. The cross-sectional micromorphology of the composites is determined by SEM and it shows that the ZnO-nws is uniformly dispersed in PEN-Ph matrix. These results indicate that the ZnO-nws act both as catalyst and reinforce element for PEN-Ph to obtain high performance crosslinked composite films. POLYM. COMPOS., 39:2801-2811, 2018. (c) 2016 Society of Plastics Engineers