本文首先通过共沉淀法制备油酸修饰的磁性Fe₃O₄纳米粒子，并将其均匀分散于正辛烷中得到磁流体，然后利用一步细乳液聚合法合成了单分散Fe₃O₄@PS磁性微球。扫描电镜分析结果表明，Fe₃O₄的粒径在13 nm左右，所形成的Fe₃O₄@PS微球的粒径在120~150 nm左右；VSM测试结果显示所合成的Fe₃O₄@PS微球具有超顺磁性，其饱和磁化强度约为25 emu/g；Fe₃O₄@PS微球表面携带明显的负电荷，其表面Zeta电势为－60 mV。反射光谱测试结果表明，Fe₃O₄@PS分散于水中形成的胶体溶液在磁场作用下呈现出明亮的结构色，具有明显的带隙特征；随着磁场强度的变化，反射峰波长可在450 ~ 650 nm进行调谐。

In this paper, Fe₃O₄ nano-particles modified by oleic acid were synthesized through coprecipitation method. The Fe₃O₄ nano-particles were dispersed into Octane to form magnetofluid. Then, Fe₃O₄@PS microspheres were prepared using one step miniemulsion polymerization method. SEM results showed that the particle size of Fe₃O₄ nano-particles is about 13 nm and the diameter ofFe₃O₄@PS microspheres is 120~150 nm or so. The magnetic measurement results showed that as-prepared Fe₃O₄@PS microspheres possess superparamagnetism and the saturation magnetization Ms is about 25 emu/g. The surface of Fe₃O₄@PS microspheres is negatively charged and the Zeta potentialis －60 mV. Reflectance spectrum measurement results showed that the colloidal suspension of Fe₃O₄@PS in aqueous solution exhibits bright structural color and obvious band-gap features under magnetic fields. With the increase of magnetic field strength, reflectance peaks wavelength can be modulated in the range 450 ~ 650 nm.