氧化鋅奈米粒子的表面改質與分散; Surface modification and dispersion of Zinc oxide nanocrystals

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/3944

Title:	氧化鋅奈米粒子的表面改質與分散;Surface modification and dispersion of Zinc oxide nanocrystals
Authors:	蔡佳銘;Jia-Ming Cai
Contributors:	化學工程與材料工程研究所
Keywords:	紫外光屏蔽;氧化鋅;奈米粒子;矽烷;表面改質;surface modification;UV shielding;silane;Zinc oxide;nanoparticles
Date:	2006-07-03
Issue Date:	2009-09-21 12:26:39 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	摘要　早先徐志宗學長利用乙二醇(EG)當螯合劑，將酸鹼中和水解得到氫氧化鋅，加熱縮合後得到粒徑約6nm ，在乙二醇中分散透明的奈米氧化鋅；其合成方式的最大優點是高分散性和高固含量，但缺點是產物有殘留的鹽類離子無法簡易去除，而且和水、丙酮、乙醇等溶劑接觸後粒子會團聚。本研究依照其方法做出奈米氧化鋅後，經過陰離子界面活性分子的螯合，去除表面羥基而取代成較長鏈之有機烷基，而可萃取到非極性溶劑。除了對改質反應之溫度、時間及效果作研究外，並利用XRD、DLS、TGA、UV、IR 等鑑定證明改質之結果。　　研究發現，藉由油酸當成螯合劑，可將在EG 中的氧化鋅萃取到toluene、 n-hexane、醋酸丁酯和n-octane 中。本來在EG 中分散透明的氧化鋅表面帶有羥基保護，添加油酸加熱後，使油酸之COOH 基與氧化鋅之羥基形成共價。包覆一層油酸的奈米粒子可均勻的透明分散在非極性的溶劑中。甚至原本在EG 中略有聚集的粒子，經改質後還能拆回成一次粒子的大小（~8nm）。而除了油酸之外，類似的結構的脂肪酸如亞麻仁油酸也有相同的效果。包覆亞麻仁油酸的氧化鋅經過加熱硬化後還可直接當成抗紫外光塗層。　　經過油酸包覆後轉到油相的氧化鋅可進一步去除油酸，再包覆氧化矽或矽烷等小分子。經氧化矽包覆後的奈米粒子即使經過高溫燒結，由XRD分析結果，粒子依然維持在6nm左右的結晶大小。而包覆油酸的粒子經過燒結後結晶長大至 32nm。兩相比較，可以間接證明氧化鋅表面的確包覆完整一層的氧化矽層。包覆氧化矽後的粒子可穩定透明懸浮在水中。不論液相懸浮液或乾燥成之固相塊材 ZnO@SiO2都可展現良好的螢光效果。在液相中為綠光範圍（Max 535nm）在固相中為黃橘光範圍（Max 590nm）。另外我們也嘗試以含環氧基之GPS矽烷來包覆奈米氧化鋅。經過包覆GPS的氧化鋅可透明分散在水相溶劑中。 Abstract A highly effective and large scale method was found to transfer ZnO nanocrystals (~5.7nm NCs) prepared in EG to non-polar solvents. This was accomplished by capping the ZnO NCs with Oleic acid (OA) or Linoleic acid (LinOA). FTIR and TGA analysis indicated that OA is bonded to surface of ZnO by bidentate chelating and controlled chelating types could be possible.The amount of capping agent required was ~8 molecule/nm2. The capped NCs formed a highly transparent (T>90%) dispersion in n-hexane even at 16wt%. The dispersed NCs could be further coated with silica or alkyl silane in the non-polar solvent via the nano-emulsion method then transfer back to polar solvent. The so obtained ZnO@SiO2 nanoparticles showed a very high Photoluminescence efficiency in aqueous suspension. The ZnO@SiO2 nanoparticles obtained exhibited a broad green emission band at about 535nm in aqueous suspension and yellow-orange emission band at 590nm as bulk pieces. The further application were disirable for functional nanocomposites and optical material.
Appears in Collections:	[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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