Mueggenburg Klara E, Lin Xiao-Min, Goldsmith Rodney H, Jaeger Heinrich M
James Franck Institute and Department of Physics, The University of Chicago, 929 E. 57th St., Chicago, Illinois 60637, USA.
Nat Mater. 2007 Sep;6(9):656-60. doi: 10.1038/nmat1965. Epub 2007 Jul 22.
Nanoparticle superlattices are hybrid materials composed of close-packed inorganic particles separated by short organic spacers. Most work so far has concentrated on the unique electronic, optical and magnetic behaviour of these systems. Here, we demonstrate that they also possess remarkable mechanical properties. We focus on two-dimensional arrays of close-packed nanoparticles and show that they can be stretched across micrometre-size holes. The resulting free-standing monolayer membranes extend over hundreds of particle diameters without crosslinking of the ligands or further embedding in polymer. To characterize the membranes we measured elastic properties with force microscopy and determined the array structure using transmission electron microscopy. For dodecanethiol-ligated 6-nm-diameter gold nanocrystal monolayers, we find a Young's modulus of the order of several GPa. This remarkable strength is coupled with high flexibility, enabling the membranes to bend easily while draping over edges. The arrays remain intact and able to withstand tensile stresses up to temperatures around 370 K. The purely elastic response of these ultrathin membranes, coupled with exceptional robustness and resilience at high temperatures should make them excellent candidates for a wide range of sensor applications.
纳米粒子超晶格是由紧密堆积的无机粒子组成的混合材料，这些粒子由短的有机间隔物隔开。到目前为止，大多数工作都集中在这些体系独特的电子、光学和磁行为上。在此，我们证明它们还具有卓越的机械性能。我们聚焦于紧密堆积纳米粒子的二维阵列，并表明它们可以被拉伸穿过微米尺寸的孔洞。由此形成的独立单层膜可以延伸数百个粒子直径，而无需配体交联或进一步嵌入聚合物中。为了表征这些膜，我们使用力显微镜测量了弹性性能，并使用透射电子显微镜确定了阵列结构。对于用十二烷硫醇连接的直径为6纳米的金纳米晶体单层，我们发现其杨氏模量约为几吉帕。这种非凡的强度与高柔韧性相结合，使膜在覆盖边缘时能够轻松弯曲。这些阵列保持完整，能够承受高达约370 K的拉伸应力。这些超薄膜的纯弹性响应，再加上在高温下的卓越稳健性和弹性，使其成为广泛传感应用的极佳候选材料。
