SEU-FEI Nano-Pico Center, Key Lab of MEMS of Ministry of Education, Southeast University, Nanjing 210096, China.
Nanoscale. 2017 Sep 28;9(37):13915-13921. doi: 10.1039/c7nr04554a.
Using liquid cell TEM, we imaged the formation of CoO nanoparticle rings. Nanoparticles nucleated and grew tracing the perimeter of droplets sitting on the SiN solid substrate, and finally formed necklace-like rings. By tracking single nanoparticle trajectories during the ring formation and an estimation of the forces between droplets and nanoparticles using a simplified model, we found the junction of liquid nanodroplets with a solid substrate is the attractive site for CoO nanoparticles. Coalescing droplets were capable of pushing nanoparticles to the perimeter of the new droplet and nanoparticles on top of the droplets rolled off toward the perimeter. We propose that the curved surface morphology of the droplets created a force gradient that contributed to the assembly of nanoparticles at the droplet perimeter. Revealing the dynamics of nanoparticle movements and the interactions of nanoparticles with the liquid nanodroplet provides insights on developing novel self-assembly strategies for building precisely defined nanostructures on solid substrates.
使用液体细胞 TEM，我们对 CoO 纳米颗粒环的形成进行了成像。纳米颗粒在坐在 SiN 固体基底上的液滴周围成核和生长，最终形成项链状环。通过在环形成过程中跟踪单个纳米颗粒轨迹，并使用简化模型估计液滴和纳米颗粒之间的力，我们发现与固体基底相接的液滴交界处是 CoO 纳米颗粒的吸引力位点。聚结的液滴能够将纳米颗粒推到新液滴的周边，而位于液滴顶部的纳米颗粒则滚向周边。我们提出，液滴的曲面形态创造了一个力梯度，有助于纳米颗粒在液滴周边组装。揭示纳米颗粒运动的动力学以及纳米颗粒与液滴之间的相互作用为在固体基底上构建精确定义的纳米结构的新型自组装策略提供了思路。
