Olarte-Plata Juan D, Bresme Fernando
Department of Chemistry, Imperial College London White City Campus, W12 0BZ London, United Kingdom.
J Chem Phys. 2020 May 29;152(20):204902. doi: 10.1063/5.0008237.
Janus particles (JPs) are a special kind of colloids that incorporate two hemispheres with distinct physical properties. These particles feature a complex phase behavior, and they can be propelled with light by heating them anisotropically when one of the hemispheres is metallic. It has been shown that JPs can be oriented by a homogeneous thermal field. We show using multiscale simulations and theory that the internal mass gradient of the JPs can enhance and even reverse the relative orientation of the particle with the thermal field. This effect is due to a coupling of the internal anisotropy of the particle with the heat flux. Our results help rationalize previous experimental observations and open a route to control the behavior of JPs by exploiting the synergy of particle-fluid interactions and particle internal mass composition.
双面粒子（JPs）是一种特殊的胶体，由具有不同物理性质的两个半球组成。这些粒子具有复杂的相行为，当其中一个半球为金属时，通过对其进行非均匀加热，它们可以被光驱动。研究表明，JPs可以被均匀热场定向。我们通过多尺度模拟和理论表明，JPs的内部质量梯度可以增强甚至反转粒子与热场的相对取向。这种效应是由于粒子的内部各向异性与热流的耦合。我们的结果有助于合理解释先前的实验观察结果，并开辟了一条通过利用粒子-流体相互作用和粒子内部质量组成的协同作用来控制JPs行为的途径。
