邊界效應對擴散泳行為的影響:圓柱形粒子在狹窄圓柱形孔道中

Abstract

本論文探討一個帶電的圓柱形粒子在充滿電解質溶液且不帶電的圓柱孔道中軸向擴散泳運動，來模擬粒子在有邊界的擴散泳行為。我們著重在化學泳的影響其包含兩種不同型態的電雙層極化以及來自陰陽離子擴散係數不同造成的電泳效應。由數值模擬的結果顯示出在有孔道邊界的出現對於粒子的擴散泳行為有顯著的影響。舉例來說，在低電解質濃度的情況下，粒子將朝向低濃度端泳動。在其它的幾何形狀中，比如說，球形粒子在球形空腔中。這個現象只有在表面電位超過150 mV才會出現，然而在本論文的幾何形狀中，我們在低表面電位(25 mV)就可觀察到此現象，這說明了邊界的存在以及粒子的形狀還有帶電狀況對於擴散泳行為都有顯著的影響。

The presence of a boundary on the diffusiophoretic behavior of a particle is modeled by considering the diffusiophoresis of a charged, finite cylindrical particle along the axis of an uncharged cylindrical pore filled with electrolyte solution. We focus on the effect of chemiphoresis including two types of double-layer polarization and that of electrophoresis coming from the difference in the diffusivity of cations and that of anions. The results of numerical simulation reveal that the presence of the pore can have a significant influence on the diffusiophoretic behavior of the particle. For instance, under the conditions of low electrolyte concentration, the particle tends to migrate to the low concentration side. In other geometry, example, sphere in a spherical cavity. This phenomenon occurs only if the surface potential exceeds ca. 150 mV, but it can be observed even at a low surface potential (ca. 25 mV) in the present geometry.