Gulliver UMR CNRS 7083, ESPCI Paris, PSL Research University, 10 rue Vauquelin, 75005 Paris, France.
Physical and Theoretical Chemistry Laboratory, Department of Chemistry-University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom.
Phys Rev Lett. 2019 Aug 30;123(9):098001. doi: 10.1103/PhysRevLett.123.098001.
Switching on high activity in a relatively dense system of active Janus colloids, we observe fast clustering, followed by cluster aggregation towards full phase separation. The phase separation process is however interrupted when large enough clusters start breaking apart. Following the cluster size distribution as a function of time, we identify three successive dynamical regimes. Tracking both the particle positions and orientations, we characterize the structural ordering and alignment in the growing clusters and thereby unveil the mechanisms at play in these regimes. In particular, we identify how alignment between the neighboring particles is responsible for the interruption of the full phase separation. Our large scale quantification of the phase separation kinetics in active colloids points towards the new physics observed when both alignment and short-range repulsions are present.
在一个活跃的 Janus 胶体的相对密集系统中开启高活性，我们观察到快速聚集，随后是向完全相分离的聚集。然而，当足够大的簇开始分解时，相分离过程会中断。通过跟踪簇大小分布随时间的变化，我们确定了三个连续的动力学状态。跟踪粒子的位置和方向，我们描述了在生长簇中的结构有序性和排列，从而揭示了这些状态下的作用机制。特别是，我们确定了相邻粒子之间的对齐如何导致完全相分离的中断。我们对活性胶体中相分离动力学的大规模量化表明，当存在取向和短程排斥时，会出现新的物理现象。
