Tungsten (W)-doped vanadium dioxide (VO2) particles were successfully synthesized by hydrolysis of vanadyl sulfate mingled with a small amount of sodium tungstate dihydrate and subsequent calcination. XPS analyses demonstrated that the vanadium oxide was composed of stoichiometric VO2, and the doped W content in VO2 particles could be easily controlled by the concentration of W precursor. XRD patterns indicated that all the W-doped VO2 particles were monoclinic crystals, and the W dopant almost had no influence on the crystal structure of VO2 particles. DSC analyses displayed that the critical phase transition temperature of VO2 particles could be reduced to room temperature or even lower by increasing the dopedWfraction. UV-vis-NIR spectra showed that the W-doped VO2 particles embedded acrylic coating had very good thermochromic performance. r 2007 Elsevier B.V. All rights reserved.

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.

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.

Europium(III) (Eu3þ)-doped polyurethane films were prepared by mixing Eu-methacrylic acid complex (Eu(MA)3) with aliphatic polyurethane oligomer and subsequently curing under UV irradiation. Transmission electron microscopy photos and the appearance of the resulting hybrid films showed that phase separation occurred only at an Eu(MA)3 content above 20 wt.-%. Fluorescence spectra indicated that the fluorescence of Eu3þ was barely influenced by the polyurethane matrix and its intensity increased with an Eu(MA)3 content in the range of approximately 0 to 10 wt.-%. An obvious applied external-field-dependent magnetization (M) of polyurethane/Eu(MA)3 films, namely, an increasingMat low field and a decreasingMat high field, was observed at room temperature from the hysteresis loops, which was influenced by both the Eu(MA)3 content and the ultrasonication imposed on the coatings before curing. It seems that ultrasonication leads to a thermodynamically-unstable structure of Eu3þ in hybrid films, which can be fixed by UV curing but gradually rearranges to its original form during the thermal-curing process, and enhances the diamagnetic part of the hybrid film. Thus, the magnetic property of Eu3þ-doped polyurethane film at room temperature can be adjusted by simply changing the preparation method and the Eu(MA)3 content instead of the type of Eu3þ-organic complex.

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.