本論文分為兩大部分，分別為非典型浸潤表面與微粒在彎曲液面之爬升行為。 第一部分-非典型浸潤表面 非典型液體浸潤表面(Atypical liquid-infused surface，ALIS)在製備上有簡易、快速的優勢，而且具有非常高的氣泡接觸角及液滴接觸角(> 160o)、極低的接觸角遲滯(< 2o)性質。將兩種多孔性基材：超親水奈米過濾膜與拉伸後的聚四氟乙烯(polytetrafluoroethylene，PTFE)膜，分別置於水中與正癸烷中，水浸潤之奈米過濾膜為水浸潤表面(water-infused surface)；正癸烷浸潤之聚四氟乙烯膜為液態烷類浸潤表面(alkane-infused surface)。體積2 L的微小液滴或氣泡在上述兩種僅傾斜2o的浸潤表面上即可平順移動，而且可以觀察到液滴在液態烷類浸潤表面上滾動的行為，與一般的超疏水表面相同。界面活性劑可以用來降低界面張力，一般來說會降低超疏水表面的接觸角，同時增加接觸角遲滯現象，但在非典型液體浸潤表面上，界面活性劑對潤濕行為的影響幾乎可以忽略。在界面活性劑的加入下，流體在表面上更容易滑移，但也會因為界面活性劑的表面再活化(surface remobilization)現象，造成流體終端速度在不同界面活性劑濃度下有不同的變化。此外，非典型液體浸潤表面還具備一定的自我修復的能力，於浸潤表面施加一定程度的物理刮痕後，依然保有流體在表面上低傾斜角即可滑移的特性，在浸潤液體中耐用程度相當高。 第二部分-微粒在彎曲液面爬升行為之研究 自然界中，一些水生昆蟲發展出一套利用表面張力的方式上岸，稱為彎月液面爬升，他們將身體固定成特殊姿勢使自己爬上彎月液面。本研究針對微粒形狀與彎月液面形態對爬升行為之影響進行分析。釐米級的片狀微粒使用塗黑之PET片剪製而成，形狀分別為三角形、正方形與長方形；而三種不同形態的彎月液面，包含：懸垂液滴(Pendant drop)、液橋(Liquid bridge)、座滴(Sessile drop)。結果顯示：因為重力的影響大過毛細力，使正方形與三角形之PET片傾向沿著液面滑落並停留於彎月液面底端；然而，長方形PET片卻可以藉由垂直方向的表面張力差爬上彎月液面且其爬升的末位置會在液面曲率接近零的地方，此時，向上的毛細力與重力可以達成平衡。最後，以更細微的片狀粉末置於彎月液面，可以觀察到隨著片狀粉末不斷補充，利用少量的片狀粉末即可迅速包覆整個彎月液面。 ;This study contains two topics: atypical liquid-infused surface and meniscus-induced motion of tiny objects. Part I - Atypical liquid-infused surface Atypical liquid-infused surfaces (ALIS) which demonstrate very high bubble/drop angles (> 160o) and ultra-low contact angle hysteresis (CAH < 2o) have been facilely fabricated. Porous hydrophilic nano-filtration membrane and hydrophobic stretched polytetrafluoroethylene film were submerged in water (water-infused surface) and in decane (alkane-infused surface), respectively. The air bubble/liquid drop (2 L) can move with ease on ALIS in submerged conditions at a low tilted angle of 2o. The rolling motion of a water drop is observed, similar to its motion on superhydrophobic surface. It is known that the addition of surfactants can reduce the interfacial tensions of water drop and intensifies CAH of water drop on superhydrophobic surfaces. But it has negligible effects on wetting properties of ALIS. In the presence of surfactant, the fluid particle moves readily on ALIS but its velocity exhibits a non-monotonic variation with surfactant concentrations due to surface remobilization. Mechanically damaged ALIS demonstrates the self-healing ability of its wetting properties and preserves the particle motion even at low inclination. Part II - Meniscus-induced motion of tiny objects In nature, some water-walking insects have developed the meniscus-climbing technique depended on surface tension. They ascended by fixing their body posture without moving their legs. In this work, the effects of floating particle shape and meniscus curvature on the meniscus-ascending behavior are explored. The flat particles with millimeter-size are made of polyethylene terephthalate (PET) sheets, and their shapes vary from triangle, square, to rectangle. Three types of menisci are considered, including pendant drop, liquid bridge, and sessile drop. For particles with triangular and square shapes, they tend to slide down and stay at the bottom of menisci because the gravitational force wins over the capillary force. However, the rectangular sheet is able to climb the meniscus surface due to uneven lateral capillary force. The meniscus curvature of its equilibrium position is close to zero, but the upward capillary force balances the particle weight. Next, we replace PET sheet with smaller flaky aluminium powder and put it on the surface of menisci. The result show the powder will spread and cover the meniscus rapidly.
