Keng Pei Yuin, Shim Inbo, Korth Bryan D, Douglas Jack F, Pyun Jeffrey
Department of Chemistry, University of Arizona, Tucson, AZ 85721, USA.
ACS Nano. 2007 Nov;1(4):279-92. doi: 10.1021/nn7001213.
We describe the synthesis and characterization of polymer-coated ferromagnetic cobalt nanoparticles (CoNPs). The synthesis of end-functionalized polystyrene surfactants possessing amine, carboxylic acid, or phosphine oxide end-groups was accomplished using atom-transfer radical polymerization. This versatile synthetic method enabled the production of multigram quantities of these polymeric surfactants that stabilized ferromagnetic CoNPs when dispersed in organic media. An in-depth investigation into the synthesis of polystyrene-coated ferromagnetic CoNPs was also conducted using various combinations of these polymeric surfactants in the thermolysis of dicobaltoctacarbonyl (Co(2)(CO)(8)). Moreover, the application of a dual-stage thermolysis with Co(2)(CO)(8) allowed for the preparation of large samples (200-820 mg) per batch of well-defined and dispersable ferromagnetic nanoparticles. Characterization of these functionalized nanoparticle materials was then done using transmission electron microscopy, X-ray diffraction, vibrating sample magnetometry, and thermogravimetric analysis. Self-assembly of these dipolar nanoparticles was investigated in solutions cast onto supporting substrates, where local nematic-like ordering of nanoparticle chains was observed along with a tendency of adjacent chains to form "zippering" configurations, both phenomena having been predicted by recent simulations of dipolar fluids in conjunction with van der Waals interactions.
我们描述了聚合物包覆的铁磁性钴纳米颗粒（CoNP）的合成与表征。使用原子转移自由基聚合完成了具有胺基、羧基或氧化膦端基的末端功能化聚苯乙烯表面活性剂的合成。这种通用的合成方法能够制备多克量的这些聚合物表面活性剂，它们在分散于有机介质中时能稳定铁磁性CoNP。还使用这些聚合物表面活性剂的各种组合，在二钴八羰基化合物（Co₂(CO)₈）的热解过程中，对聚苯乙烯包覆的铁磁性CoNP的合成进行了深入研究。此外，采用Co₂(CO)₈的双阶段热解能够每批制备大量（200 - 820毫克）明确且可分散的铁磁性纳米颗粒。然后使用透射电子显微镜、X射线衍射、振动样品磁强计和热重分析对这些功能化纳米颗粒材料进行表征。在浇铸到支撑基板上的溶液中研究了这些偶极纳米颗粒的自组装，在其中观察到纳米颗粒链的局部向列状有序排列以及相邻链形成“拉链”构型的趋势，这两种现象均已被近期结合范德华相互作用的偶极流体模拟所预测。
