BACKGROUND: Polyacrylate/silica nanocomposite latexes have been fabricated using blending methods with silica nanopowder, in situ polymerization with surface-functionalized silica nanoparticles or sol-gel processes with silica precursors. But these approaches have the disadvantages of limited silica load, poor emulsion stability or poor film-forming ability.

UV-curable polymer/nanosized indium-doped tin oxide (ITO) nanocomposite coatings were fabricated by blending ITO slurry and oligomer and reactive monomers. The preparation of ITO slurry and the effect of the ITO content on the electrical conductivity, hardness and optical properties of the nanocomposite coats were investigated. It was found that the electric conductivity and UV absorbance of the nanocomposite coats increased while the hardness and refractive index first increased then decreased with increasing ITO concentration since too high ITO resulted in the incomplete curing of the coatings.

WO3·H2O nanotubes are successfully synthesized with the aid of intercalated polyaniline (PANI) under relatively mild conditions. More interestingly, the WO3·H2O nanotubes have a rectangular cross-section structure formed through a rolling mechanism. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, Fourier-transform infrared analysis, UV-vis-near-IR spectroscopy, selected-area electron diffraction, and vibrating-sample magnetometry analysis are employed to characterize the morphology, structure, and properties of the nanotubes.

The de-agglomeration and dispersion of nano-TiO2 powder is little reported, although nano-TiO2 powder has been widely used due to its unique optical properties. In this study, an agitator bead mill (MiniZETA 03E, Netzsch) accompanied with an ultrasonicator was employed to de-agglomerate the nano-TiO2 powder in butyl acetate, and the effects of ultrasonic pretreatment, dispersant dosage, agitation speed, solid content of TiO2 suspension, and bead diameter were systemically investigated. It is found that ultrasonic pretreatment leads to short grinding time to reach the limiting fineness, low specific energy input, and small limiting mean size. All other technical parameters have also some influence on the limiting fineness and grinding time. However, the former strongly depends on agitation speed while the latter on both agitation speed and dispersant dosage. A solvent-borne nano-TiO2 suspension with limiting mean size of 110 nm can be successfully result under the optimal technical conditions and showed excellent UV-shielding property and transparence when it was incorporated into polyester/melamine coatings.

Transparent zirconia (ZrO2) nanocrystal dispersions in butyl acetate (BAc) or tetrahydrofuran (THF) were prepared by functionalizing zirconia nanocrystals, synthesized from a solvothermal reaction of zirconium (IV) isopropoxide isopropyl alcohol complex in benzyl alcohol, with 3-methacryloxypropyltrimethoxysilane (MPS), and were embedded into UV-curable polyurethane (PU) coatings. It was found that the ZrO2 concentration was the dominating factor influencing the transparency of the ZrO2 dispersion, while the molar ratio of MPS to ZrO2 was rather efficient in adjusting the amount of MPS attached. Phase separation of the ZrO2 nanocrystals in polyurethane coatings was observed, and was strongly related to the MPS-modified ZrO2 (MPS-ZrO2) content and the amount of MPS chemically bonded. The phase separation of the PU/ZrO2 nanocomposite coatings appeared more seriously for higher MPS-ZrO2 content and higher amounts of MPS attached; thus the transparency of the nanocomposite coatings was lower. However, completely transparent PU/ZrO2 nanocomposite coatings could be still achieved even with a ZrO2 content up to 7.5 wt.-% using a ZrO2/BAc dispersion. Improvements in pendulum hardness, microhardness and scratch resistance of the polyurethane coatings via addition of MPS-ZrO2 were demonstrated, but were not remarkable because of the low cross-linking efficiency of the MPS-ZrO2 nanoparticles resulting from the poor compatibility of the MPS-ZrO2 nanoparticles with the pure PU oligomers.