Preparation and Properties of Transparent Zinc Oxide/Silicone Nanocomposites for the Packaging of High-Power Light-Emitting Diodes

New transparent zinc oxide (ZnO)/silicone nanocomposites with outstanding integrated properties, including a high UV-shielding efficiency and transparency, bigger thermal conductivity, and lower dielectric constant, were successfully developed; they were prepared by the uniform dispersion of organic modified nano-ZnO in a silicone matrix through in situ polymerization. The ZnO precursor was prepared by a direct precipitation method, which was then calcinated at different temperatures to produce nano-ZnO with various morphologies and sizes. The effects of the size, surface nature, and content of nano-ZnO on the key properties (e.g., optical and dielectric properties, thermal conductivities) of the composites were systematically investigated. The results show that the organic nano-ZnO prepared by 3-methacryloxypropyltrimethoxysilane can increase the dispersion of nano-ZnO in silicone resin, and the interfacial adhesion between inorganic and organic phases, and consequently improve the integrated properties of nanocomposites. The increase of the particle content and size of ZnO in composites can lead to high thermal conductivity and UV-shielding efficiency but lower visible-light transparency, so there is an optimum content and size of ZnO in composites to obtain the best integrated properties of the composites. Specifically, the nanocomposite containing 0.03 wt % organic nano- ZnO with an average size of 46 +/- 0.4 nm not only had a high visible-light transparency, UV-shielding efficiency, and thermal conductivity but also possessed a low dielectric constant and loss and met the requirements of high-performance electronic packaging for high-power light-emitting diodes. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121:2018-2028, 2011