油酸修饰TiO2纳米棒的溶剂热合成及形貌调控研究

采用溶剂热法在两种不同反应体系中制备TiO₂ 纳米棒, 采用X射线粉末衍射法(XRD)、透射电镜(TEM)、红外光谱(FT-IR)和热重分析(TG)对产物的结构、形貌和表面修饰状态进行表征。结果表明, 表面修饰和结晶过程是影响TiO₂ 纳米棒形貌的主要因素, 在无水反应体系中, 当钛盐与油酸配比为1︰10时所制TiO₂ 纳米棒的长径比可达11.5, 是相同配比水解反应体系产物的2.3倍。这一方面是因为油酸在TiO₂表面的选择性吸附促使晶粒沿一维方向生长, 增加其用量提高了纳米棒的长径比; 另一方面, 无水体系反应速率较水解体系缓慢, 有利于晶粒的充分生长和纳米棒之间的“定向附着”, 显著增大了纳米棒的长径比。所得最佳长径比TiO₂ 纳米棒对变压器油的正冲击击穿强度显示出良好的改性作用。

Solvothermal Synthesis and Morphological Control of TiO2 Nanorods Modified with Oleic Acid

TiO₂ nanorods were prepared by solvothermal method in two reaction systems. The structure, morphology and surface modification state of the as-obtained nanorods were characterized by X-ray diffractometer (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and thermalgravimetric method (TG). The results indicate that the surface modification and crystallization process are the main factors that affect the morphology of TiO₂ nanorods. In the nonaqueous reaction system, the aspect ratio of as-prepared TiO₂ nanorods increase to 11.5 with the mole ratio of tetrabutyl titanate to oleic acid at 1: 10, which is 2.3 times of that obtained in the hydrolyzation system under the same ratio of reactants. The reason for this phenomenon is that the selective adsorption of oleic acid on the surface of TiO₂ limits the one-dimensional orientation growth of crystals. The aspect ratio of TiO₂ nanorods can be enhanced by increasing the amount of oleic acid. Furthermore, nonaqueous reaction facilitates the adequate growth of crystals and the oriented attachment of nanorods due to its lower reaction velocity, leading to the significant increase of aspect ratio of nanorods. The as-obtained nanorods with the optimum aspect ratio exhibit good modification effect on the positive impulse breakdown strength of transformer oil.