Effect of the origin of ZnO nanoparticles dispersed in polyimide films on their photoluminescence and thermal stability

Polyimide (PI) films containing dispersed ZnO nanoparticles were prepared from both zinc nitrate hexahydrate (designated as Zn(NO 3 ) 2 /PI) and ZnO nanoparticles, 2‐nm average primary size (ZnO/PI). This work shows how the origin of ZnO affects both the photoluminescence and thermal decomposition of the film. The presence of ZnO derived from Zn(NO 3 ) 2 ·6H 2 O was confirmed by X‐ray diffraction technique. The fluorescent intensities from Zn(NO 3 ) 2 /PI and ZnO/PI were much higher than that from pure PI films. When the ZnO concentration exceeded a certain saturation level, the emission intensity decreased due to the undesirable aggregation of ZnO. At the same concentration, ZnO/PI exhibited higher emission intensity than Zn(NO 3 ) 2 /PI. All samples prepared under nitrogen emitted higher intensity than their counterparts prepared under argon. The ZnO/PI film was thermally more stable than the Zn(NO 3 ) 2 /PI one. From TEM images of 117.6 mol% ZnO/PI films, the ZnO aggregates, whose average size was 17–90 nm, were well distributed throughout the film but poorly dispersed in nanometer range. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008