吸管力對帶電膠體叢集於介面之影響; Interfacial Colloid-Clusters Driven by Capillary Forces

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題名:	吸管力對帶電膠體叢集於介面之影響;Interfacial Colloid-Clusters Driven by Capillary Forces
作者:	賴山強
貢獻者:	物理學系
關鍵詞:	物理類
日期:	2010-08-01
上傳時間:	2011-07-13 16:25:04 (UTC+8)
出版者:	行政院國家科學委員會
摘要:	帶電膠體於空氣/水介面形成膠體叢集的現象最近頗受實驗族群的注意。研究中發現這些膠體叢集之膠體-膠體平均距離都相當的長，大約有三微米，遠大於膠體-膠體於大體膠體溶液之距離。對於如何產生此尺觀結構之機制仍然是一個謎，但毫無疑問的，此膠體叢集之結構和長程吸引力非凡得瓦種類有關。為探討此詭異二維帶電膠體於空氣/水介面之行為，本計盡擬從理論出發，分析此類糸統之總能量的三項力源貢獻，亦即二極屏蔽靜電力、凡得瓦力以及毛細力。在這三項能量貢獻中，我們將致力於毛細力，考慮其為主要的長程吸引力。在實際操作上，我們則採用半徑大小相同約十微米之帶電膠體，並同時參考近期理論與實驗工作之相資料，估算其他和界面相關且符合物理量之合理值，如表面膠體電荷、底拜屏蔽長度等。在最佳化的問題上，本計晝擬用兩種發展中之科技的目前進步水準的方法，計算二維膠體叢集之最低能量。希望透過比較最佳化後的微米結構，瞭釋表面膠體叢集被局限在空氣水界面的現象。本計畫也擬探討二維膠體叢集之成長圖案並和實驗作比較。Recent experimental efforts on charged colloids trapped at the fluid/water interface have witnessed the formation of colloid-clusters. It was observed in these studies that the average inter-colloidal distance is surprisingly large on the order of approximately and often greater than 3 μm much farther than that in bulk colloidal dispersion. The mechanism giving rise to these mesoscopic structures remains an unclear puzzle unquestionably due to some kind of a long-range attractive force which is certainly not of van der Waals origin. In this project, we analyze theoretically the three main contributions, namely, the electrostatic (screened Yukawa and dipolar), van der Waals and capillary potentials, to the total energy of a two dimensional (2D) charged colloids spread on the fluid/water interface. Among them, we shall pay due attention to the capillary potential and consider it as a dominant source causing the long-range attraction. Realistically, we choose to study charged colloids possessing the same radius equal approximately to 10 μm and consult recent theoretical and experimental works for a reasonable estimation of other interfacial related quantities such as the charge of a surface colloid , Debye screening length,..etc which are indispensable in a colloid-cluster calculation. By appealing to two state-of-the-art optimization algorithms, we calculate the 2D colloid-clusters by searching their lowest energies. We shall investigate the optimized total energies and study the mesoscopic structures of surface colloid-clusters trappped at the fluid/water interface. We plan to deduce any regularity in the growth pattern of the 2D colloid-clusters and compare to any available experiment. 研究期間：9908 ~ 10007
關聯:	財團法人國家實驗研究院科技政策研究與資訊中心
顯示於類別:	[物理學系] 研究計畫

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