邊界效應對擴散泳行為的影響： 球形粒子在球形或圓柱形孔洞中

Abstract

本論文利用有限元素法探討邊界效應對球形膠體粒子的擴散泳行為的影響。所考慮的系統包括單顆硬球在球形孔洞中任意位置的泳動、單顆軟球在球形孔洞中任意位置的泳動以及單顆硬球沿一長圓管軸心的泳動。吾人深入討論了擴散泳極化效應的情形，定義出兩種不同方向的極化電場，使擴散泳行為得以合理被解釋。並探討電解質溶液中離子與帶電粒子的靜電交互作用力對擴散泳行為的影響。 數值模擬的結果顯示粒子的特性、邊界的幾何形狀、粒子與邊界的距離、粒子表面電位、電雙層厚度及離子的擴散係數大小對擴散泳速度有顯著的影響。在不同的條件下，粒子會往不同方向移動，本論文所獲結果提供擴散泳設計與操作的參考資訊。

The boundary effect on the diffusiophoretic behavior of a particle is analyzed theoretically by considering the diffusiophoresis of a charged sphere under arbitrary surface potential and double-layer thickness at an arbitrary position in an uncharged spherical cavity or along the axis of a cylindrical pore. We show that the factors key to the present problem include two types of double-layer polarization, the repulsion between the particle and the coions accumulated immediately outside the double layer, the difference in ionic diffusivities, and the osmotic flow of solvent. The presence of a boundary can have a profound influence on the behavior of a particle.