Abstract:
ZnO nanoparticles with various morphologies were successfully synthesized by a gas phase reaction in this work. Effects of O₂ and N₂ flow rate as well as position for collecting particle on the synthesized ZnO characteristics, which are particle size distribution and morphology were investigated. An increase in O₂ flow rate resulted in morphological change of ZnO tetrapods which were deposited on the reactor wall into plate-like morphology. Particle collection using particle filter could give rise to ZnO particles with a nearly spherical shape. Meanwhile, an increase in O₂ flow rate in the system with improved collecting method could lead to short pod of ZnO particles. When N₂ flow rate was increased the size of ZnO particle was decreased. In addition, photoluminescence of poly(methylmetacrylate) (PMMA) and ZnO composite film, which was fabricated by the melt mixing method with a two-roll mill, was studied in this work. Three types of ZnO particles with different nominal sizes and concentrations were employed to investigate the optimal conditions for preparing the composite with preferable optical and mechanical properties. It was found that the composite films prepared from originally synthesized ZnO particles could exhibit the much improved photoluminescent property when compared with commercial ZnO particles. Interestingly, ZnO nanoparticles could effectively shield UV irradiation when compared with the micrometer-size ZnO particles. The UV absorption and shielding of composite film depended on type and concentration ZnO particles added. It was also found that mixing of ZnO particles into PMMA did not affect the glass transition temperature of the composite films.
