宏觀系統的特性往往取決於其內部整體的性質，亦即界面的貢獻可忽略不計。但當系統尺寸縮小到微米尺度時，表面張力和表面組成等界面性質產生貢獻並開始扮演角色。當系統尺寸變成奈米等級後，由於其表面積對體積的比值急遽上升，系統的特性將會被界面性質強烈地影響，導致有些微米或奈米尺度的系統會呈現出宏觀系中統未觀察到的特別行為。舉例而言，我們過去的研究顯示含界面活性劑的溶液與高分子薄膜，其系統性質如表面張力或臨界微胞濃度會呈現出依系統尺寸而變化的行為(界面現象)。此外，用來描述液體在微管道滲透動力學的Washburn方程在某些奈米尺度下會不精確(輸送現象)。很明顯地，宏觀系統的理論常不足以描述和解釋奈米系統的異常現象。 在此三年期計畫中，我們將從理論與實驗的角度分別探討在奈米系統所出現的異常界面與輸送現象。理論研究的部分將主要會採用多體耗散粒子動力學模擬方法進行探討；在實驗部分將會考慮奈米乳液及其玻璃態與微米液滴之自我運動特性。計畫第一至二年，我們將以理論模擬研究流體在開放奈米管道的滲透動力行為，並了解其相關的控制機制。在實驗部分，則利用高耗能超音波設備，嘗試製備穩定的奈米乳液玻璃，並分析分散相液滴大小對玻璃特性的影響。同時，將結合馬倫哥尼效應與低遲滯表面，找出可讓微液滴呈現自我運動的系統。計畫第二至三年，我們持續以理論模擬研究奈米液滴在粗糙表面的潤濕行為，將考慮表面粗糙之拓樸結構(連續與不連續)的影響。在實驗部分，我們則發展低耗能方法製備奈米乳液玻璃，並瞭解其形成機制；此外，我們將藉由控制表面的粗糙度或其他方式，操控可自我運動微液滴的運動方向。 ;In macroscopic systems, the system characteristics depend mainly on their bulk properties. As the system size decreases to the microscale, however, the interfacial properties such as interfacial tensions and surface excess come into play. Down to the nanoscale level, the system behavior is significantly influenced by interfacial properties due to dramatic increment of the surface-to-volume ratio. Consequently, some micro- and nano-scale systems display special phenomena which cannot be observed in macroscopic systems. For example, the surfactant solutions and polymer thin films show the size-dependent behavior such as surface tension and critical micelle concentration (interfacial phenomena). Moreover, Washburn’s equation describing the penetration dynamics in closed channels fails at some conditions (transport phenomena). Obviously, the theories for macroscopic systems are not sufficient to explain the abnormal behaviors in nanoscale systems. In this three-year project, both theoretical and experimental approaches will be employed to explore the abnormal behaviors emerged in nanoscale systems, particularly for interfacial and transport phenomena. The theoretical work will involve mainly “Many-body dissipative particle dynamics” simulations and underlying mechanisms, while the experimental work will be concerned with nano-emulsions and their glass states and directed self propulsion of microdroplets. In the 1st ~ 2nd years, the penetration dynamics through open nanocapillaries will be investigated by simulations. Moreover, the formation of a nanoemulsion glass will be explored via high-energy ultrasonic processor. The systems of microdroplets self-propelling on substrates will also be constructed. In the 2nd ~ 3rd years, abnormal wetting phenomena of nanodroplets on grooves will be explored by simulations, and the influence of surface roughness topology will be studied. Furthermore, the low-energy approach will be used to fabricate nanoemulsion glasses. The method to direct self-propelled microdroplets will be developed as well.
