Three-dimensional self-assembly of metallic rods with submicron diameters using magnetic interactions.
Three-dimensional self-assembly of metallic rods with submicron diameters using magnetic interactions.
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DOI：
10.1021/ja037642h
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发表时间：
2003-09
影响因子：
15
通讯作者：
J. Love;Adam R Urbach;Mara G. Prentiss;G. Whitesides
中科院分区：
文献类型：
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作者：
J. Love;Adam R Urbach;Mara G. Prentiss;G. Whitesides
具有亚微米直径的金属棒包含盘状铁磁部分，可自组装成高度稳定的六边形密排棒阵列。这些棒通过电沉积在多孔氧化铝膜上制成，并由金和镍的交替部分组成。铁磁镍部分的厚度约为棒直径的一半（400 nm）；这种几何形状将“易”磁化轴定向为垂直于棒的长轴。用稀土磁体对棒进行磁化，然后对悬浮液进行超声处理后，棒会自发组装成三维 (3D) 束，平均包含 15-30 个棒。棒的宏观模型表明，在无缺陷、六边形密堆积排列中，棒的磁偶极子最稳定的方向是在同心环中，偶极子头尾相连。这种配置最大限度地减少了束的能量，并且不会为结构生成净偶极子。这项工作提供了一个简单的证明，即铁磁物体之间的磁相互作用可以通过自组装指导和稳定有序 3D 结构的形成。
Metallic rods with submicron diameters that contain disklike ferromagnetic sections self-assemble into highly stable, hexagonally close-packed arrays of rods. The rods were fabricated by electrodeposition in porous alumina membranes and comprised alternating sections of gold and nickel. The thicknesses of the ferromagnetic nickel sections were approximately one-half the diameter of the rods (400 nm); this geometry orients the "easy" axis of magnetization perpendicular to the long axis of the rod. After magnetization of the rods with a rare-earth magnet, followed by sonication of the suspension, the rods spontaneously assembled into three-dimensional (3D) bundles that, on average, contained 15-30 rods. A macroscopic model of the rods suggests that the most stable orientation of the magnetic dipoles for rods in a defect-free, hexagonally close-packed arrangement is in concentric rings with the dipoles oriented head-to-tail. This configuration minimizes the energy of the bundle and does not generate a net dipole for the structure. This work provides a simple demonstration that magnetic interactions between ferromagnetic objects can direct and stabilize the formation of ordered, 3D structures by self-assembly.