我們製備了大小約為5 nm之氧化鋅奈米粒子，並以含壓克力基之矽烷3-(trimethoxysilyl)propylmethacrylate (MPS)進行表面改質。原先僅在乙二醇分散之氧化鋅，經過改質後可得到乾粉，並可再重新分散至許多溶劑。根據紅外光譜及核磁共振分析， MPS是先以tridental 和 monodental 的形式螯合於氧化鋅表面，然後多餘的MPS再接到以monodental 形式螯合的MPS分子外，形成雙層結構。由於粒子表面所接著之矽烷本身帶有壓克力基。若未完全縮合，則又留有氫氧基。所以改質後的氧化鋅不但可以分散至極性較強的溶劑如酒精，亦可分散到極性較弱的溶劑如四氫氟喃和甲基乙基酮。根據小角度X光散射分析，氧化鋅奈米粒子是球型，並在溶劑中會形成動態粒子簇。分散液的黏度隨著奈米粒子濃度的增加而呈現指數成長。其指數值 ~?4代表在高濃度下的粒子可能產生結構。分散液在濃度高達70 wt % 時仍具有高穿透度( T% > 85 )。雖然有流動性但是黏度甚高，是非牛頓流體。我們又製作了氧化鋅/矽膠的奈米複合材料，並塗佈於基材上嘗試作為UV光之阻隔膜。在氧化鋅固含量為65 wt % 而膜厚為5 ?m的情況下，可以將 350 nm以下之UV光完全阻隔，並且在可見光範圍仍呈現高的穿透度。最後我們將這些奈米複合材料進行QUV測試以驗證其耐久性。發現可以在照度高溼氣條件下支撐1400小時。換算成一般戶外條件約可支撐八年。ZnO nanoparticles (~5 nm) have been prepared and surface-modified with 3-(trimethoxysilyl)propylmethacrylate (MPS). The product is a dry powder which can be re-dispersed in many solvents. Based on the results of IR and NMR analysis, the directly anchored MPS exhibits both tridental and monodental structures, while a second layer of partially condensed silane are linked to the monodental ones. Due to the existence of both methacrylate group and residual hydroxyl, the ZnO@MPS powder can be dispersed in both polar and non-polar solvents. The dispersion remained transparent (T% > 85) and fluidic even at a loading as high as 70 wt %. The viscosity of the dispersion increases exponentially with the filler loading following the Quemada equation. An exponent ~ ?4 confirms that the fillers are un-aggregated even at such a high loading. ZnO/silicone nanocomposites are then prepared and coated on substrates as UV blocking film. A complete blockage of the UV radiation (<350 nm) has been achieved with a 5 ?m coating containing 65 wt% ZnO, while the transparency in the visible range (> 90 T% for >385 nm) could still be maintained. The durability of these nanocomposite films was further investigated by the standard QUV test.
