超顺磁单分散性Fe_3O_4磁纳米粒的制备及性能表征

Study on the Synthesis and Properties of Superparamagnetic Monodisperse Fe_3O_4 Nanoparticles

具有超顺磁单分散性的Fe3O4磁纳米粒在生物医学材料领域有着广泛的用途.本研究在水、乙醇和甲苯混合体系74℃回流的条件下制备了具有超顺磁性的表面含油酸的Fe3O4磁纳米粒,研究了制备过程中OH-浓度的变化对磁纳米粒的表面性能、粒径、分散性及磁性能的影响,并对其机理进行了初步探讨.采用XRD、FTIR、DLS、TEM和VSM等手段对制备的磁纳米粒进行表征.结果表明,当NaOH/Fe(Ⅱ)摩尔比<8时,Fe3O4磁纳米粒表面含油酸可良好地分散于非极性溶剂中,NaOH的加入对磁纳米粒的粒径和饱和磁化强度等性能无明显影响;而当NaOH/Fe(Ⅱ)摩尔比≥8时,Fe3O4磁纳米粒仅能分散于水等极性溶剂中,饱和磁化强度虽可增至40A.m2/kg,但为多分散且易团聚.

There are extensive applications for superparamagnetic Fe3O4 nanoparticles in the field of biomaterials.Superparamagnetic magnetite nanoparticles coated with oleic acid were prepared in the refluxing mixed system of water,ethanol alcohol and toluene at 74℃.The effect of the OH^- concentration on the surface properties,size,dispersion and magnetic properties of magnetite nanoparticles was studied systematically.The properties of magnetite nanoparticles were tested by X-ray diffraction （XRD）,fourier transform infrared （FTIR）,dynamic light scattering （DLS）,transmission electron microscopy （TEM） and vibrating sample magnetometer （VSM）.The results show that when the molar ratio of NaOH to Fe（Ⅱ） is less than 8,magnetite nanoparticles coated with oleic acid can be dispersed easily in nonpolar solvents.The addition of NaOH has no obvious influence on the size and the saturation magnetization of magnetite nanoparticles.While the molar ratio of NaOH to Fe（Ⅱ） is more than 8,magnetite nanoparticles can only be dispersed in polar solvents,such as water.Although the saturation magnetization increases to 40A·m^2/kg,magnetite nanoparticles are polydisperse and easy to agglomerate in water.