Stürmer Julian, Seyrich Maximilian, Stark Holger
Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany.
J Chem Phys. 2019 Jun 7;150(21):214901. doi: 10.1063/1.5080543.
Mixtures of active and passive colloids show an intriguing dynamics of self-assembling, which is driven by the active component. Self-phoretic active colloids generate sinks in a chemical concentration field that cause passive colloids to drift toward active colloids by diffusiophoresis. The strength of this effective attraction is governed by the diffusiophoretic parameter, which determines the drift velocity. Simulating the Langevin dynamics of the colloids, we determine the state diagram for increasing diffusiophoretic strength and fixed active velocity. Three main states are distinguished. For weak attraction, passive particles are first scattered in the simulation box and then form a colloidal cloud around its center. Increasing the diffusiophoretic parameter further, passive particles oscillate between the cloud and a compact cluster, which embeds active colloids. Ultimately, in the third state, all particles collapse into a single stable cluster. In the collapse regime, the clustering dynamics of the largest cluster follows a logistic function and the mean cluster velocity vs cluster size decays with a power law. Throughout this article, we discuss our simulation results with regard to the experiments of Singh et al., Adv. Mater. 29(32), 1701328 (2017).
活性胶体与被动胶体的混合物展现出一种由活性成分驱动的、引人入胜的自组装动力学。自泳活性胶体在化学浓度场中产生汇，这会导致被动胶体通过扩散泳向活性胶体漂移。这种有效吸引力的强度由扩散泳参数决定，该参数决定了漂移速度。通过模拟胶体的朗之万动力学，我们确定了扩散泳强度增加且活性速度固定时的状态图。区分出三种主要状态。对于弱吸引力，被动粒子首先散布在模拟盒中，然后在其中心周围形成胶体云。进一步增加扩散泳参数，被动粒子会在云与嵌入活性胶体的紧密团簇之间振荡。最终，在第三种状态下，所有粒子坍缩成一个单一的稳定团簇。在坍缩区域，最大团簇的聚集动力学遵循逻辑函数，且平均团簇速度与团簇大小随幂律衰减。在本文中，我们将结合辛格等人发表于《先进材料》2017年第29卷第32期，第1701328页的实验来讨论我们的模拟结果。
