Fe_3O_4表面原位引发可控/“活性”聚合制备磁性聚苯乙烯纳米粒子

Preparation of Magnetic Polystyrene Nanoparticles by the Controlled/“Living” Free Radical Polymerization of Styrene

采用化学共沉淀方法合成了Fe3O4纳米粒子,用3-甲基丙烯酰氧基丙基三甲氧基硅烷(3-MPS)对其进行表面接枝修饰,然后以苯乙烯(St)为单体,过氧化苯甲酰(BPO)为引发剂,4-羟基-2,2,6,6-四甲基哌啶-1-氧化物自由基(HTEMPO·)为稳定自由基介质,采用可控“/活性”自由基聚合技术在修饰后的Fe3O4纳米粒子表面原位引发聚合,制备了粒径小、分布窄、磁含量高的磁性聚苯乙烯(PS)纳米粒子.X射线衍射(XRD)研究表明,所合成的Fe3O4粒子为尖晶石结构.凝胶渗透色谱(GPC)分析表明,聚苯乙烯的分子量与反应时间呈较好的线性关系.透射电镜(TEM)观察表明,所制备的磁性聚苯乙烯纳米粒子的粒径在20-30nm之间.热重(TG)分析得到磁性聚苯乙烯纳米粒子的磁含量为62.6%.振动样品磁强计(VSM)测试结果表明,磁性聚苯乙烯纳米粒子的比饱和磁化强度为31.7emu·g-1,呈现单磁畴结构.

Magnetite nanoparticles were synthesized by chemical coprecipitation of ferrous chloride and ferric sulfate. The obtained magnetite nanoparticles were surface-modified with 3-methacryloxypropyltrimethoxy silane （3- MPS） to form terminal vinyl groups as grafting sites. The polystyrene （PS）-graffed magnetite nanoparticles were prepared by controlled/＂living＂ free radical polymerization by using benzoyl peroxide （BPO） as an initiator in the presence of 4-hydroxyl-2,2,6,6-tetramethyl-1-piperidinyloxy （HTEMPO·）. XRD measurement showed the spinel structure for the magnetite nanoparticles. GPC analysis suggested the relationship between number average molecular weight of PS and polymerization time to be with approximate linear. The PS-graffed magnetite nanoparticles are uniform with diameters in the range from 20 nm to 30 nm from TEM. The content of magnetite in magnetic PS nanoparticles was 62.6% from the analysis of TG. The results of magnetic performance by VSM displayed that the magnetic PS nanoparticles exhibited the characteristics of single domain system when saturated magnetization was equal to 31.7 emu·g^-1.