本研究中我們採取不同的表面改質方法在奈米氧化鋯晶粒表面接上數種短有機酸，然後探討改質後奈米氧化鋯的分散性質。我們將清洗乾淨的奈米氧化鋯表面改質醋酸(HAc)、甲基丙烯酸(MA)、異丁酸(IBA)和丁酸(BA)，然後檢查使特定有機酸改質之氧化鋯分散的溶劑種類以及分散後粒子團聚情形。氧化鋯表面單獨以醋酸改質者可以分散在高極性、氫鍵作用力強的溶劑裡。若單獨以MA、IBA和BA改質，其產物需要先除水，再以甲苯(或乙苯) 浸潤粒子表面，經過烘除甲苯即可分散在低極性的溶劑裡。若以MA、IBA、BA對已經醋酸改質的氧化鋯做酸根置換，其產物表面有醋酸的影響，便可分散在較高極性的溶劑當中。對於酸根置換的樣品，我們以NMR、TGA等分析，可以判斷兩種改質劑在奈米氧化鋯上分別接枝量，由而了解對醋酸根置換能力為BA>IBA>MA。上述改質氧化鋯樣品在各種溶劑中分散能力可以用Hansen 溶解度參數(HSP)來歸納，亦可以DLVO理論來探討立體障礙、電荷斥力以及凡德瓦爾力對分散的影響。 表面有MA、IBA、BA改質的奈米粒子是以二次粒子的型態分散在有機溶劑中。若在改質的過程中增加除水的步驟，可以使二次粒子縮小。所以二次粒子成因可能與系統中水分有關。我們又發現吡啶具有特別的溶劑特性，而可使上述改質氧化鋯以幾乎沒有團聚的一次粒子型態分散。 ;Different methods have been employed to modify the surface of zirconia nanoparticles (NPs) with various short carboxylic acids, and have led to different colloidal properties. The colloidal behavior of zirconia nanoparticles with a single capping ligand can be characterized by the range of dispersible solvents. Acetate-capped zirconia NPs can be dispersed in highly polar solvents. In the case of methacrylic acid(MA), isobutyric acid(IBA), butyric acid(BA) capped zirconia NPs cannot disperse in any solvents readily. However, after soaking with toluene and further drying, they became dispersible in non-polar solvents. The acetic ligands on acetate-capped zirconia NPs can be exchanged with MA, IBA or BA and become dispersible in more polar solvents. TGA and NMR analysis of ligand exchange samples can tell us the quantity of ligands on zirconia surface, also the ligand exchange ability of ligands. Strangely, most surface modified NPs showed smaller size in pyridine compare to other solvents. Hansen solubility parameters and DLVO theory can be used to describe the dispersion behavior of these surface modified nanoparticles.
