Department of Mechanical Engineering and Institute for Complex Molecular Systems , Eindhoven University of Technology, 5612 AZ, Eindhoven, The Netherlands.
Proc Natl Acad Sci U S A. 2014 May 6;111(18):6554-9. doi: 10.1073/pnas.1322857111. Epub 2014 Apr 18.
Interactions between surfaces and particles in aqueous suspension are usually limited to distances smaller than 1 μm. However, in a range of studies from different disciplines, repulsion of particles has been observed over distances of up to hundreds of micrometers, in the absence of any additional external fields. Although a range of hypotheses have been suggested to account for such behavior, the physical mechanisms responsible for the phenomenon still remain unclear. To identify and isolate these mechanisms, we perform detailed experiments on a well-defined experimental system, using a setup that minimizes the effects of gravity and convection. Our experiments clearly indicate that the observed long-range repulsion is driven by a combination of ion exchange, ion diffusion, and diffusiophoresis. We develop a simple model that accounts for our data; this description is expected to be directly applicable to a wide range of systems exhibiting similar long-range forces.
悬浮在水中的表面和颗粒之间的相互作用通常局限于小于 1μm 的距离。然而，在来自不同学科的一系列研究中，在没有任何额外外部场的情况下，已经观察到颗粒在长达数百微米的距离上产生排斥。尽管已经提出了一系列假设来解释这种行为，但负责这种现象的物理机制仍然不清楚。为了识别和分离这些机制，我们在一个定义明确的实验系统上进行了详细的实验，使用了一种最小化重力和对流影响的设置。我们的实验清楚地表明，观察到的长程排斥是由离子交换、离子扩散和扩散泳动的组合驱动的。我们开发了一个简单的模型来解释我们的数据；这种描述预计将直接适用于表现出类似长程力的广泛系统。
