Department of Chemistry, Indian Institute of Technology, Madras, Chennai, 600 036, India.
Nanoscale Res Lett. 2009 Jun 14;4(9):1090-102. doi: 10.1007/s11671-009-9365-z.
The surface-initiated ATRP of benzyl methacrylate, methyl methacrylate, and styrene from magnetite nanoparticle is investigated, without the use of sacrificial (free) initiator in solution. It is observed that the grafting density obtained is related to the polymerization kinetics, being higher for faster polymerizing monomer. The grafting density was found to be nearly 2 chains/nm2for the rapidly polymerizing benzyl methacrylate. In contrast, for the less rapidly polymerizing styrene, the grafting density was found to be nearly 0.7 chain/nm2. It is hypothesized that this could be due to the relative rates of surface-initiated polymerization versus conformational mobility of polymer chains anchored by one end to the surface. An amphiphilic diblock polymer based on 2-hydroxylethyl methacrylate is synthesized from the polystyrene monolayer. The homopolymer and block copolymer grafted MNs form stable dispersions in various solvents. In order to evaluate molecular weight of the polymer that was grafted on to the surface of the nanoparticles, it was degrafted suitably and subjected to gel permeation chromatography analysis. Thermogravimetric analysis, transmission electron microscopy, and Fourier transform infrared spectroscopy were used to confirm the grafting reaction.
从磁铁矿纳米粒子表面引发的苯甲基丙烯酸酯、甲基丙烯酸甲酯和苯乙烯的 ATRP 反应，无需在溶液中使用牺牲（游离）引发剂。观察到，接枝密度与聚合动力学有关，对于聚合更快的单体，接枝密度更高。对于快速聚合的苯甲基丙烯酸酯，接枝密度约为 2 条/纳米 2。相比之下，对于聚合较慢的苯乙烯，接枝密度约为 0.7 条/纳米 2。据推测，这可能是由于表面引发聚合的相对速率与通过一端锚定在表面的聚合物链的构象迁移率有关。基于 2-羟乙基甲基丙烯酸酯的两亲性嵌段共聚物是从聚苯乙烯单层合成的。均聚物和接枝嵌段共聚物的 MNs 在各种溶剂中形成稳定的分散体。为了评估接枝到纳米粒子表面的聚合物的分子量，将其适当脱附，并进行凝胶渗透色谱分析。热重分析、透射电子显微镜和傅里叶变换红外光谱用于证实接枝反应。
