Repetitive heterocoagulation of oppositely charged particles for enhancement of magnetic nanoparticle loading into monodisperse silica particles.
Repetitive heterocoagulation of oppositely charged particles for enhancement of magnetic nanoparticle loading into monodisperse silica particles.
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DOI：
10.1021/la903266e
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发表时间：
2010-03
期刊：
影响因子：
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通讯作者：
Hideki Matsumoto;D. Nagao;M. Konno
中科院分区：
文献类型：
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作者：
Hideki Matsumoto;D. Nagao;M. Konno
不透明带电粒子的重复异质凝聚，以制造具有高负载量的磁性纳米粒子的高度单分散的磁性二氧化硅粒子。用N-三甲氧基硅丙基-N，N，N-三甲基氯化铵（TSA）对磁性纳米粒子进行表面改性，制备了带正电的磁性纳米粒子，并在碱性条件下与二氧化硅粒子进行了共凝聚，使磁性纳米粒子表面带负电，从而防止磁性纳米粒子的氧化。所得的均匀涂覆有磁性纳米颗粒的二氧化硅核的颗粒进一步涂覆有具有硅酸钠的薄二氧化硅层，以增强胶体稳定性并避免磁性纳米颗粒从二氧化硅核解吸。五次重复的异质凝聚和二氧化硅涂层可以将磁性二氧化硅颗粒的饱和磁化强度增加到27.7emu/g，保持颗粒尺寸的变异系数（C（V））小于6.5%。通过用能量色散X射线光谱法测量单个颗粒的Fe-Si原子比来确认磁性组分的高度均匀的负载。
Oppositely charged particles were repetitively heterocoagulated to fabricate highly monodisperse magnetic silica particles with high loading of magnetic nanoparticles. Positively charged magnetic nanoparticles prepared by surface modification with N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (TSA) were used to heterocoagulate with silica particles under basic conditions to give rise to negative silica surface charge and prevent the oxidation of the magnetic nanoparticles. The resultant particles of silica core homogeneously coated with the magnetic nanoparticles were further coated with thin silica layer with sodium silicate in order to enhance colloidal stability and avoid desorption of the magnetic nanoparticles from the silica cores. Five repetitions of the heterocoagulation and the silica coating could increase saturation magnetization of the magnetic silica particles to 27.7 emu/g, keeping the coefficient of variation of particle sizes (C(V)) less than 6.5%. Highly homogeneous loading of the magnetic component was confirmed by measuring Fe-to-Si atomic ratios of individual particles with energy dispersive X-ray spectroscopy.