磁性颗粒表面改性过程中包覆结构和过程的分析

Study of Surface Structure and process of Surface Modification of Magnetic Particles

本文从油酸钠包覆Fe3O4磁性粒子的机理出发,通过FT-IR,TEM,DSC对磁流体的表面结构和包覆量进行分析,得出以下结论:油酸根和磁性粒子间由于库仑力的作用结合在一起,油酸根中的-C=O均裂成两个相等的-C-O-单键,同磁性粒子表面结合形成第一层化学吸附;溶液中还有过量的油酸钠一端疏水和另一端亲水,是疏水端向第一层靠拢,亲水端伸入水中,物理吸附形成第二层,单是物理吸附并不牢固,最终得到稳定的单层化学吸附油酸钠包覆的磁流体,油酸钠表面活性剂量的理论和实际分析也证明油酸钠是单层包覆在Fe3O4粒子表面。

Sodium Oteate coated Fe3O4 magnetic fluid was successfully prepared by a conventional coprecipitation method. The surface structure and surfactant weight were studied by FT-IR, TEM and DSC. It＇s concluded that the process of sodium oleate coated Fe3 O4 magnetic particles is： firstly, oleate radical and Fe3 O4 magnetic particles are combined due to electrostatic interaction; Secondly, the C= O of sodium oleate is splited into two equivalent C- O which bridges the surfactant and magnetic particles; The excess sodium oleate is weakly physically adsorbed on the primary layer of the sodium oleate coated magnetic particles. But the second layer was so weakly that its easily washed away by ethanol, so the chemically adsorbed single layer gained at last which is also proved by the surfactant weight.