Thesis (M.Eng.)--Chulalongkorn University, 2007

Zinc oxide (ZnO) is semiconductor materials due to its good optical, thermal and electrical properties. In this work, ZnO nanostructures were synthesized by combination of electrospinning and solvothermal techniques. First, zinc precursor, i.e. zinc acetate (Zn(CH3CO2)2) was formed into nanofibers by electrospinning with the aid of poly(vinyl alcohol) (PVA). Subsequently, the PVA/zinc acetate composite nanofibers were subjected to the solvothermal process, in which octanol was used as the reaction medium, in order to synthesize zinc oxide nanostructure. The effect of quantity of excess zinc acetate, reaction temperature and reaction time for solvothermal process were investigated to find growth mechanism of ZnO nanostructures. It was found that when the solvothermal temperature is in the range of 170 to 250 °C, all products are ZnO in the hexagonal phase. The products from the solvothermal synthesis, using PVA/zinc acetate composite nanofibers without excess zinc acetate in the reaction medium, are nanofibers of polycrystalline ZnO. When there is excess zinc acetate presented in the reaction system, ZnO nanorods are formed and deposited on the ZnO nanostructures. The length of the rods increases with an increase in either reaction temperature or the quantity of excess zinc acetate. Moreover, zinc acetate within the composite fibers can be converted into ZnO, while PVA is still retained. Zinc acetate starts to completely convert into ZnO at 200 oC and the growth of the ZnO crystals is more immense as the reaction temperature is raised to 250 oC.