Shen Meng, Li Honghao, Olvera de la Cruz Monica
Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
Department of Applied Physics, Northwestern University, Evanston, Illinois 60208, USA.
Phys Rev Lett. 2017 Sep 29;119(13):138002. doi: 10.1103/PhysRevLett.119.138002. Epub 2017 Sep 28.
Surface polarization in ion-containing heterogeneous dielectric media such as cell media and emulsions is determined by and determines the positions of the ions. We compute the surface polarization self-consistently as the ions move and analyze their effects on the interactions between electro-neutral, ion-containing droplets using coarse-grained molecular dynamics simulations based on the true energy functional. For water droplets immersed in oil, the interdroplet interaction is attractive, and the surface polarization makes the major contribution. By contrast, for oil droplets in water, the ion-surface induced charge interaction is repulsive and counteracts the attraction between the ions, leading to a small attractive interaction between the droplets. This research improves our understanding of self-assembly in mixed phases such as metal extraction for recovering rare earth elements and nuclear waste as well as water purification.
在诸如细胞培养基和乳液等含离子的非均匀介电介质中，表面极化由离子的位置决定，同时也决定离子的位置。我们在离子移动时自洽地计算表面极化，并使用基于真实能量泛函的粗粒化分子动力学模拟来分析其对电中性含离子液滴间相互作用的影响。对于浸没在油中的水滴，液滴间的相互作用是吸引性的，并主要由表面极化作用导致。相比之下，对于水中的油滴，离子 - 表面感应电荷相互作用是排斥性的，抵消了离子间的吸引力，导致液滴间存在微弱的吸引性相互作用。这项研究增进了我们对混合相自组装的理解，例如用于回收稀土元素和核废料的金属萃取以及水净化过程。
