Self-Propulsion Mechanism of Active Janus Particles in Near-Critical Binary Mixtures.
Self-Propulsion Mechanism of Active Janus Particles in Near-Critical Binary Mixtures.
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DOI：
10.1103/physrevlett.115.188305
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发表时间：
2015-06
影响因子：
8.6
通讯作者：
S. Samin;R. van Roij
中科院分区：
文献类型：
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作者：
S. Samin;R. van Roij
浸在近临界二元混合物中的金冠Janus粒子可以使用照明来推进。我们采用非等温扩散界面方法研究了单胶体的自推进机制。我们把这种运动归因于围绕粒子成核的微米级液滴边缘的体积力。因此，常用的表面速度概念不能解释自推进。颗粒的游动速度与液滴的形状和尺寸有关，这由所谓的临界等温线决定。存在两种不同的游动状态，取决于液滴是否部分或完全覆盖颗粒。有趣的是，游泳速度对温度的依赖性是非单调的，在这两个制度。
Gold-capped Janus particles immersed in a near-critical binary mixture can be propelled using illumination. We employ a nonisothermal diffuse interface approach to investigate the self-propulsion mechanism of a single colloid. We attribute the motion to body forces at the edges of a micronsized droplet that nucleates around the particle. Thus, the often-used concept of a surface velocity cannot account for the self-propulsion. The particle's swimming velocity is related to the droplet shape and size, which is determined by a so-called critical isotherm. Two distinct swimming regimes exist, depending on whether the droplet partially or completely covers the particle. Interestingly, the dependence of the swimming velocity on temperature is nonmonotonic in both regimes.