This paper presents a novel and facile method for the fabrication of ZnO hollow spheres. In this approach, zinc ions were first adsorbed onto the surfaces of sulfonated polystyrene core-shell template spheres, and then reacted with NaOH to form a ZnO crystal nucleus, which was followed by a growth step to form ZnO nanoshells. During the formation of ZnO nanoshells or later on, the template spheres were "dissolved" in the same media to obtain ZnO hollow spheres directly. Neither additional dissolution nor calcination process was needed in this method to remove the templates, and the reaction conditions were very mild: neither high temperature nor long time was needed. Transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Brunauer-Emmett-Teller analysis were used to investigate the morphology, surface composition, crystalline structure, specific surface area, and porosity of the ZnO hollow spheres, respectively. UV-visible spectra show that these ZnO hollow spheres had very good photocatalytic activity.

Poly(styrene butylacrylate) latex/nano-ZnO composites were prepared by blending poly(styrene butylacrylate) latex with a water slurry of nano-ZnO particles, and the effects of certain parameters, such as particle size, dispersant type, dispersing time and others, on the dispersibility, mechanical properties, ultraviolet (UV) shielding and near infrared (NIR) shielding were investigated with transmission electron microscopy (TEM), an Instron testing machine, dynamic mechanical analysis and ultraviolet-visiblenear infrared (UV-VIS-NIR) spectrophotometry. TEM observation showed that dispersants with long chains are better than those with short chains at enhancing the dispersibility of nano-ZnO particles in a matrix; extending dispersing time also improves the dispersibility of nano-ZnO particles in a matrix. Instron tests showed that the nanocomposite polymers embedded with nano-ZnO particles had much higher tensile strength than the corresponding composite polymers with micro-ZnO particles. As the nano-ZnO content increased, the temperature of glass transition (T g ) of the nanocomposite polymer embedded with 60 nm ZnO particles first increased then decreased, but 100 nm ZnO and microZnO particles seemed to have no influence on the T g of the composite polymers. The better dispersibility of nano-ZnO particles resulted in higher T g values. Increasing nano-ZnO content or dispersibility could enhance the UV shielding properties of the nanocomposite polymers, and 60 nm ZnO particles could more effectively shield UV rays than 100 nm ZnO particles. Micro-ZnO particles basically had no effect on the UV absorbance of the composite polymers. A blueshift phenomenon was observed at 365 nm when nano-ZnO particles were present in the nanocomposite polymers. NIR analysis indicated that as nano-ZnO content increased, the NIR shielding of the nanocomposite polymers increased, but the NIR shielding properties seemed to be more influenced by particle size than by the nano-effect.

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The fabrication of monodispersed hollow spheres in varying sizes and shapes is very interesting and has a lot of potential applications. This paper provides a very simple route to preparing hollow titania spheres using polystyrene (PS) as a template. In this approach, the titania shells were first formed and the PS cores were dissolved subsequently, even synchronously, in the same medium; neither an additional dissolution nor a calcination process was needed to remove the PS cores. Transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and Barret-Emmet-Teller measurements were used to characterize the monodispersed hollow titania spheres. A possible formation mechanism of the hollow spheres was proposed.

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