邊界的幾何形狀與粒子表面的非均勻帶電對其電泳行為之影響

Abstract

本論文在考慮電雙層極化影響下，以有限元素法研究表面非均勻帶電之球型粒子以及帶固定電荷密度之粒子在一狹窄管道中之電泳行為。粒子表面帶電的非均勻度、電雙層厚度、邊界的形狀以及帶電情況是主要的探討變因。 從數值模擬的結果發現許多有趣的現象，舉例而言，對平均電位相同的膠體粒子而言，非均勻度越大，粒子的電泳速度越慢。另外，粒子經過非帶電之狹窄管道時會加速通過，而此現象也和實驗觀察吻合；在帶電之管道中，粒子的電泳現象更為複雜，和電雙層厚度有密切關係。這些觀察與發現在膠體粒子的電動力學上有相當大之應用潛力。

The electrophoretic behavior of a spherical particle with nonuniform surface potential and that with constant surface charge density along a narrow converging-diverging cylindrical pore were investigated by the finite element method. The effect of double layer polarization was also considered in this study. The key factors we concerned include: the degree of nonuniformity, the double layer thickness, the shape and the charged condition of the boundary. Several interesting results are observed. For instance, we show that the mobility of nonuniform particle is smaller than that of uniform ones. Also, the increase of mobility around the converging-diverging section is also observed in experiment. These phenomena are both fundamental and practical in electrokinetic of colloid.