雙性聚電解質的擴散泳:溫度與形狀的效應

Diffusiophoresis of Zwitterionic Polyelectrolytes: Effects of Temperature and Shape

許彥瑞(Yen-Jui Hsu)

指導教授 ： 徐治平

國立臺灣大學/工學院/化學工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201600754

摘要

延伸先前關於剛體球及軟球的研究，本論文討論了在物體為非剛體的情況下，以聚電解質來做為擴散泳的運動物體。在第一個主題裡，主要討論的是電荷可調解的聚電解質粒子在多離子容易中的擴散泳行為，在調節溫度、電解質濃度及電解質離子種類時，使其更接近真實情況時，運動行為會受到怎麼樣的影響。在結果中可以看到pH值及溫度明顯的影響了球的帶電情況，而黏度及擴散系數等參數也受到影響的情況下產生了更複雜及有趣的運動行為變化。在第二個問題中，我們第一次探討了在物體形狀為超環時的擴散泳行為，使用了KCl溶液來觀察在不同的電雙層厚度、不同的超環大小、不同的軟硬程度及電荷密度的行為。我們可以觀察到不管是定性及定量上都與球體行為非常的不同，這歸因於流力及電力競爭下的結果，所以可以看到形狀及環境的不同可以造成不同的擴散泳行為，製造出更有趣及複雜的結果。

關鍵字

擴散泳 ； 聚電解質 ； 溫度效應 ； 超環聚電解質 ； 多離子溶液

並列摘要

Extending previous analyses on rigid particles to non-rigid ones, we model the diffusiophoresis of a polyelectrolyte (PE) in a solution. Two types of problem are considered in this thesis. In the first problem, the effects of temperature, pH, type of ionic species and bulk concentration are taken into account, and therefore, the conditions considered are more comprehensive and closer to reality than those of the available results in the literature. We show that temperature and pH influence appreciably the charged conditions of a PE, the ionic diffusivities, and the fluid viscosity, yielding complicated and interesting behaviors that are informative to device design. In the second problem, we model the diffusiophoresis of an isolated toroidal polyelectrolyte (PE) for the first time. Choosing an aqueous KCl solution for illustration, its behavior under various conditions is simulated by varying the double layer thickness, the size of toroid, and its softness and fixed charge density. We show that the behavior of the present PE can be different both quantitatively and qualitatively from that of the corresponding spherical PE. This arises from the competition of the hydrodynamic force and the electric force acting on a PE. The geometry and the nature of a PE can also influence appreciably its behavior, yielding complicated and interesting results.

並列關鍵字

Diffusiophoresis ； Polyelectrolytes ； Effect of temperature ； Toroidal polyeletrolyte ； Multiple ion

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