本研究針對奈米磁性粒子之製造與其表面修飾之特性做進一步的探討，其中應用了物理與化學表面修飾，以期製造具新功能、多應用性之納米磁性微粒。其策略為藉由表面包覆技術，於氧化鐵粒子外包覆二氧化矽，利用二氧化矽的特性，可與眾多的矽偶矽劑參與表面改質。製備過程分為三部分。首先，以二價鐵與三價鐵之鹽類與氨水(ammonium hydroxide，NH4OH )相互反應利用化學其共沉法來製備奈米微粒，，接著以油酸(oleic acid，CH3(CH2)7CH=CH(CH2)7COOH )為界面活性劑，將所得之奈米級微粒散布至水中。此製程利用雙層界面活性劑包覆方式，阻止所得之磁鐵礦粒子（magnetite，Fe3O4）聚集。最後利用水基磁性流體於極性溶劑中之均勻分散性，以溶膠凝膠法來被覆奈米級磁鐵礦粒子。本研究利用X光繞射儀、動態光散射、熱重分析儀、表面電位儀、掃描式及穿透式電子顯微鏡來鑑定粒子之性質。最終製備出穩定，不團聚之矽膠被覆之奈米級磁性微粒，以為後續之進一步研究。

The research is focused on the preparation and characterization of physically or chemically surface-modified magnetite (Fe3O4) nanoparticleswhich are expected with the benefit of a easy fabrication of functionalities, and in turn with multi-applications in many areas. Fulfilling the above goal, a strategy has developed on coating a layer of silica onto the magnetite nanopatricles, which are stabilize by the surface charge repulsion from the coated silica, and functionalities are introduced by the wildly available silane coupling agents. There are three portions of the whole process: the coprecipitation of magnetite nanoparticle involving the chemical coprecipitation of Fe(II) and Fe(III) salts with ammonia hydroxide(NH4OH); the bilayered surfactant water-based magnetic fluid with oleic acid as surfactants, and the sol-gel nanocoating of silica. The silica-coated magnetite nanoparticles are characterized by X-ray diffraction, thermogravimetry analysis, dynamic light scating
and electron microscopy.

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