Benkoski Jason J, Bowles Steven E, Korth Bryan D, Jones Ronald L, Douglas Jack F, Karim Alamgir, Pyun Jeffrey
Polymers Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
J Am Chem Soc. 2007 May 16;129(19):6291-7. doi: 10.1021/ja070779d. Epub 2007 Apr 20.
The assembly and direct imaging of ferromagnetic nanoparticles into one-dimensional mesostructures (1-D) are reported. Polymer-coated ferromagnetic colloids (19 nm, 24 nm) were assembled at a crosslinkable oil-water interface under both magnetic field induced and zero-field conditions and permanently fixed into 1-D mesoscopic polymer chains (1-9 mum) in a process referred to as Fossilized Liquid Assembly (FLA). In the FLA process, nanoparticle chains were fixed at the oil interface through photopolymerization, enabling direct visualization of organized mesostructures using atomic force microscopy. Using the FLA methodology, we systematically investigated different conditions and demonstrated that dispersed ferromagnetic colloids possess sufficient dipolar interactions to organize into mesoscopic assemblies. Application of an external magnetic field during assembly enabled the formation of micron-sized chains which were aligned in the direction of the applied field. This universal methodology is an attractive alternative technique to cryogenic transmission electron microscopy (cryo-TEM) for the visualization of nanoparticle assembly in dispersed organic media.
报道了铁磁纳米颗粒组装成一维介观结构（1-D）并进行直接成像。聚合物包覆的铁磁胶体（19纳米，24纳米）在磁场诱导和零场条件下于可交联的油水界面组装，并在一个被称为“化石液体组装”（FLA）的过程中永久固定成一维介观聚合物链（1-9微米）。在FLA过程中，纳米颗粒链通过光聚合固定在油界面，从而能够使用原子力显微镜直接观察有序的介观结构。使用FLA方法，我们系统地研究了不同条件，并证明分散的铁磁胶体具有足够的偶极相互作用以组装成介观聚集体。组装过程中施加外部磁场能够形成沿施加磁场方向排列的微米级链。这种通用方法是用于观察分散有机介质中纳米颗粒组装的低温透射电子显微镜（cryo-TEM）的一种有吸引力的替代技术。
