Synthesis of highly monodisperse particles composed of a magnetic core and fluorescent shell
Synthesis of highly monodisperse particles composed of a magnetic core and fluorescent shell
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DOI：
10.1021/la801364w
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发表时间：
2008-09-02
期刊：
影响因子：
3.9
通讯作者：
Konno, Mikio
中科院分区：
文献类型：
--
作者：
Nagao, Daisuke;Yokoyama, Mikio;Konno, Mikio
采用杂凝聚和无皂乳液聚合相结合的技术合成了由磁性二氧化硅核和荧光聚合物壳组成的高度单分散粒子。在非均相凝聚之前，用Stober法制备单分散的亚微米尺寸的二氧化硅颗粒，并且用改进的Massart法制备磁性纳米颗粒，其中在Fe 2+和Fe 3+的共沉淀之后立即加入阳离子硅烷偶联剂N-三甲氧基甲硅烷基丙基-N，N，N-三甲基氯化铵。具有负表面电位的二氧化硅颗粒与具有正表面电位的磁性纳米颗粒发生了异凝聚。用硅酸钠处理用杂凝聚法获得的磁性二氧化硅颗粒以用二氧化硅改性它们的表面。在二氧化硅包覆的磁性二氧化硅核上形成荧光聚合物壳。使用2，2 ′-偶氮双[N-（2-羧乙基）-2-2-甲基丙脒]（VA-057）的两性引发剂来控制聚合物涂覆期间磁芯的胶体稳定性。苯乙烯在疏水性荧光团芘存在下的聚合可以用荧光聚合物壳包覆核，得到具有磁性二氧化硅核和荧光聚合物壳的单分散颗粒。复合粒子在不同pH值下的zeta电位的测量表明，复合粒子具有源自VA-057引发剂的两性性质。
Highly monodisperse particles composed of a magnetic silica core and fluorescent polymer shell were synthesized with a combined technique of heterocoagulation and soap-free emulsion polymerization. Prior to heterocoagulation, monodisperse, submicrometer-sized silica particles were prepared with the Stober method, and magnetic nanoparticles were prepared with a modified Massart method in which a cationic silane coupling agent of N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride was added just after coprecipitation of Fe2+ and Fe3+. The silica particles with negative surface potential were heterocoagulated with the magnetic nanoparticles with positive surface potential. The magnetic silica particles obtained with the heterocoagulation were treated with sodium silicate to modify their surfaces with silica. In the formation of a fluorescent polymer shell onto the silica-coated magnetic silica cores. an amphoteric initiator of 2,2'-azobis[N-(2-carboxyethyl)-2-2-methylpropionamidine] (VA-057) was used to control the colloidal stability of the magnetic cores during the polymer coating. The polymerization of St in the presence of a hydrophobic fluorophore of pyrene Could coat the cores with fluorescent polymer shells, resulting in monodisperse particles with a magnetic silica core and fluorescent polymer shell. Measurements of zeta potential for the composite particles in different pH values indicated that the composite particles had an amphoteric property originating from VA-057 initiator.