Cupric oxide(CuO)nanoparticles were grown on zinc oxide(ZnO)nanorod(NR)arrays to form ZnO–CuO corn-like composites via a simple two step solution-based method.First,ZnO nanorods were grown on a glass substrate by the hydrothermal method.Afterwards,CuO crystals were photochemically deposited on ZnO NRs using ultraviolet(UV)light irradiation at room temperature.The density and size of CuO nanoparticles(NPs)on ZnO NRs can be controlled by the irradiation time of UV light.The structural and optical properties of ZnO–CuO nanocomposites were characterized by using various techniques such as UV-vis absorption spectroscopy,photoluminescence,scanning electron microscopy,energy dispersive x-ray spectroscopy,and x-ray diffraction.ZnO–CuO nanocomposites show an excellent improvement in photocatalytic characteristics compared to bare ZnO NRs.
Hyperbranched polymer structures represent a class of high-functionality building blocks with excellent three-dimensional topology for the construction of highly substituted conjugated polymers.In this contribution,an efficient microwave synthesis protocol toward the synthesis of conjugated hyperbranched polymers is presented.A novel series of soluble hyperbranched polyfluorenes (PTF1-PTF3) incorporating triazatruxene moiety as the branch units with various branching degrees have thus been successfully constructed with good yields and high molecular weight via a facile "A2+B2+C3" approach.The structures of the hyperbranched polymers were confirmed by NMR and GPC.Their thermal,optical,and electrochemical properties of the hyperbranched polymers were also investigated.The results showed that introduction of triazatruxene units into the hyperbranched structure endowed the polymer with good thermal stability and highly amorphous properties.Photophysical investigation of PTFx revealed strong blue emission in both solution and solid states.Hyperbranched polymers with higher degree of branching and proper content of linear fluorene units exhibited better photophysical properties in terms of narrow emission spectra and relatively high quantum efficiency as well as improved thermal spectral stability.The triazatruxene branching unit also played a role in raising the HOMO energy levels relative to those of polyfluorenes that would help to improve the charge injection and transport properties.The incorporation of triazatruxene unit into hyperbranched polymers has thus explored an effective avenue for constructing optoelectronic polymers with improved functional characteristics.
LAI WenYong,LIU Dong & HUANG Wei Key Laboratory for Organic Electronics & Information Displays (KLOEID)
