Meijer Janne-Mieke, Meester Vera, Hagemans Fabian, Lekkerkerker H N W, Philipse Albert P, Petukhov Andrei V
Van 't Hoff Laboratory for Physical and Colloid Chemistry , Debye Institute for Nanomaterials Science, Utrecht University , Padualaan 8 , 3584 CH Utrecht , The Netherlands.
Department of Physics , University of Konstanz , Universitätstrasse 10 , D-78457 Konstanz , Germany.
Langmuir. 2019 Apr 9;35(14):4946-4955. doi: 10.1021/acs.langmuir.8b04330. Epub 2019 Mar 28.
We employ a system of cubic colloids with rounded corners to study the close-packed monolayers that form via convective assembly. We show that by controlled solvent evaporation large densely packed monolayers of colloidal cubes are obtained. Using scanning electron microscopy and particle-tracking algorithms, we investigate the local order in detail and show that the obtained monolayers possess their predicted close-packed optimal packings, the Λ-lattice and the Λ-lattice, as well as the simple square-lattice and disordered packings. We further show that shape details of the cube corners are important for the final packing symmetry, where the frequency of the Λ-lattice increases with decreasing roundness of the corners, whereas the frequency of the Λ-lattice is unaffected. The formation of both optimal packings is found to be a consequence of the out-of-equilibrium formation process, which leads to small shifts in rows of cubes, thereby transforming the Λ-lattice into the Λ-lattice.
我们采用一种带有圆角的立方胶体系统来研究通过对流组装形成的密堆积单层。我们表明，通过控制溶剂蒸发，可以获得大量密集堆积的胶体立方体单层。利用扫描电子显微镜和粒子追踪算法，我们详细研究了局部有序性，并表明所获得的单层具有其预测的密堆积最优堆积结构，即Λ晶格和Λ晶格，以及简单的正方形晶格和无序堆积结构。我们进一步表明，立方体角的形状细节对于最终的堆积对称性很重要，其中Λ晶格的频率随着角的圆度降低而增加，而Λ晶格的频率不受影响。发现这两种最优堆积结构的形成是不平衡形成过程的结果，该过程导致立方体行发生小的位移，从而将Λ晶格转变为Λ晶格。
