在宏觀系統，系統的特性通常取決於其整體的性質。但是當系統尺寸縮小到微米尺度時，界面性質（如：表面張力）會開始扮演角色。當進入奈米等級後，系統的特性將會被界面性質強烈地影響。也就是說，有些微米或奈米尺度的系統會展現宏觀系中統無法發現的特別行為。舉例來說，描述密閉管道之穿透動力學的Washburn方程某些條件下會失效（毛細現象）。此外，奈米液滴在某些具有部分潤濕性質的紋理表面時，會自發性的向外擴張（潤濕現象）。很明顯地，宏觀系統的理論已不足以用來解釋奈米系統的異常現象。正由於系統尺寸的縮小，機械裝置（如：閥門）已變的難以製造。期望開發一些方法來製造功能可以與宏觀系統中相同的納米機械裝置。為了探索上述在奈米系統下的潤濕與毛細現象，將採用多體耗散粒子動力學模擬方法。因此，利用理論模擬研究了流體在奈米管道的穿透動力學和奈米液滴在具有規律粗糙度之部分潤表面的異常擴張。此外，基於楊-拉普拉斯方程和邊緣效應，開發了一種新型的毛細奈米閥門。為了進一步了解這種新型閥門裝置，還研究了這種系統的相圖和形態學。;In macroscopic systems, the system characteristics depend mainly on their bulk properties. As the system size decreases to microscopic systems, however, the interfacial properties such as interfacial tensions come into play. Down to the nanosopic level, the system behavior is significantly affected by interfacial properties. That is, some micro- and nanoscale systems exhibit special phenomena which cannot be observed in macroscopic systems. For instance, Washburn’s equation describing the penetration dynamics in closed channels fails at some conditions (capillary phenomenon). Furthermore, the spontaneous spreading can take place as a nanodroplet is deposited on some textured surfaces with partially wetting characteristic (wetting phenomenon). Obviously, the theories for macroscopic systems are not sufficient to explain the abnormal behaviors in nanoscale systems. Owing to the reduction of system size, some mechanical devices such as valves are difficult to fabricate. It is desirable to develop some approach to manufacture mechanical nanodevice, whose function can be the same as that in macroscopic systems. In order to explore above wetting and capillary phenomena in nanoscale systems, the theoretical work based on “many-body dissipative particle dynamics” simulations are used. Consequently, the penetration dynamics through nanoscale capillaries and the abnormal spontaneous spreading of nanodroplet on partially wetting surfaces with regular roughness were theoretically studied. Moreover, a novel capillary nanovalve based on the Young-Laplace equation and edge effect was developed. To understand the mechanism of this the valving device further, the phase diagram and morphology of such systems were studied as well.
