Blue Luminescent ZnO Nanoclusters Stabilized by Esterifiable Polyamidoamine Dendrimers and their UV-Shielding Applications

Zinc oxide quantum dots (QDs) were added to the water solutions of esterifiable polyamidoamine (PAMAMs) and the ZnO nanoclusters were prepared. The ZnO nanoclusters are stable in water and show bright blue fluorescence under UV lamp. TEM images showed that the ZnO nanoclusters consisted of numerous ZnO QDs. FTIR spectra of ZnO nanoclusters demonstrated the successful modification of ZnO QDs by the esterifiable polyamidoamine dendrimers. The UV-visible absorption spectra indicated that the ZnO nanoclusters exhibited wider and red-shifted comparing with ZnO QDs. The fluorescent spectra showed that the emission peaks at 404 nm of the ZnO QDs became weaker and a new emission peaks appeared at 330 nm after modifying the ZnO QDs with polyamidoamine dendrimers. The UV-visible transmittance spectra showed that the poly(vinyl alcohol)/ZnO nanoclusters film absorbed nearly 99% of UV light at wavelengths between 200 and 240 nm while 75% between 240 and 300 nm.