硅烷偶联剂表面修饰纳米氧化铝

Surface Modification of Nano-alumina with Silane Coupling Agent

硅烷偶联剂KH570在乙醇溶剂中以酸水溶液为催化剂进行水解后对纳米氧化铝进行湿法表面修饰改性。用灼烧法测定了粉体表面偶联包覆率，以此为指标研究了KH570的水解条件及其对偶联效果的影响。结果表明，酸种类等水解条件对偶联效果有很大影响；适宜的偶联剂水解条件为：草酸作催化剂，调pH值为3～4，室温下水解1h。适宜的纳米氧化铝表面修饰条件为：偶联剂质量分数4．5％，在45℃偶联5．5h。经红外光谱（IR）分析，氧化铝的偶联修饰机理为：硅烷偶联剂与纳米氧化铝表面的羟基发生化学键合，从而实现纳米氧化铝的表面修饰改性。改性纳米氧化铝在有机相中的分散性和稳定性均得到了改善。

Silane coupling agent KH570 was hydrolyzed in alcohol with acid solution as a catalyst. Then nanoalumina was modified with it by wet surface modification. The rate of coverage of the coupling agent was determined by roasting method. The hydrolysis conditions of KH570 and their influence on the coupling effect were investigated. It was found that the hydrolysis conditions such as the acid used had important influence on the coupling, and the proper hydrolysis conditions of the silane coupling agent were： oxalic acid as the catalyst, pH 3 -4, hydrolysis at room temperature for 1 h. The proper processing conditions for the surface modifier for nano-alumina were that the mass percent of coupling agent was 4.5% , at 45 ℃ reacting for 5.5 h. It was shown by IR that the silane coupling agent reacted with the surface --OH of the alumina, by which nano-alumina was modified. Both the dispersity and stability of the modified alumina in organic phase were improved.