Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, United States.
ACS Nano. 2013 Mar 26;7(3):2705-16. doi: 10.1021/nn400118e. Epub 2013 Feb 12.
We demonstrate a magnetic technique for assembling bidisperse and tridisperse colloidal particle fluids into a variety of complex structures with dimensionality ranging from 0-D (rings) to 1-D (chains) to 2-D (tiles). Compared with prior work on bidisperse particles that are commensurate in size, here we explore the assembly of different sized particles, and we show that due to packing constraints, new particle structures can be realized experimentally. Extending these experiments to a tridisperse system, we demonstrate that at low concentrations the smallest particle does not change the underlying crystal structures of the bidisperse system; however, it can assist in the formation of crystallite structures that were not stable in a bidisperse system. Additionally, we discovered that the smallest particle mimics the role of the ferrofluid, by shifting the locations in phase space where the bidisperse crystal structures can be experimentally obtained. Finally, we demonstrate that 3-particle crystal structures can be tuned by varying the strength of the external field, which is not possible in a 2-particle system.
我们展示了一种磁技术，可将双分散和三分散胶体粒子流体组装成各种复杂结构，其维数从 0-D（环）到 1-D（链）到 2-D（平铺）。与以前在尺寸上一致的双分散颗粒的研究相比，我们在这里探索了不同尺寸颗粒的组装，并且我们表明，由于包装限制，可以通过实验实现新的颗粒结构。将这些实验扩展到三分散系统，我们证明，在低浓度下，最小的颗粒不会改变双分散系统的基础晶体结构；但是，它可以帮助形成在双分散系统中不稳定的微晶结构。此外，我们发现最小的颗粒通过在外相空间中改变可以通过实验获得双分散晶体结构的位置来模拟铁磁流体的作用。最后，我们证明可以通过改变外部磁场的强度来调整 3 颗粒晶体结构，这在 2 颗粒系统中是不可能的。
