液滴撞擊固體平板後之潤濕行為，近年來成為一項被學界討論的課題，並且廣泛運用在不同之領域；例如噴墨印表機的墨水噴塗於紙上，農藥噴灑於葉面上，高分子3D列印噴墨等行為。因液滴撞擊平板後的液滴變化情形甚為快速，故需仰賴高速攝影機觀察其變化行為。本研究利用每秒可拍攝6770張的高速攝影機拍攝各實驗側視與俯視影像。
本研究第一部分使用不同的砂紙製造出不同粗糙度的聚碳酸酯表面，再以直徑2.14mm純水液滴撞擊不同粗糙度的聚碳酸酯基材，探討在固定高度下，表面粗糙度對液滴撞擊的影響，數值化分析潤濕直徑，液滴的高度和動態接觸角的變化，測定表面粗糙度的特殊影響，並將相差極大粗糙度的表面，由通過原子力顯微鏡分析其表面形態。在慣性主導的液滴撞擊平板後初始階段，五種基材表現出類似的行為，預期的回縮反衝階段，表現出如釘栓般的pinning行為，這是由於當液滴處在Wenzel狀態下，在一個基材上隨機分布的缺陷，這些缺陷造成的摩擦力，實際上會抵抗三相線的移動，造成三相線的停止，不過當能量重新分配後使得向內移動的力量高於此摩擦力時，三相線便會向內移動。
本研究第二部分觀察不同濃度瓜爾豆膠水溶液(guar gum solution)撞擊疏水性parafilm之行為。瓜爾豆膠是一種高分子半乳甘露聚醣(galactomannan)溶液屬於剪切稀釋(shear thinning)非牛頓(non-Newtonian)流體。瓜爾豆膠分子會吸附於液-氣界面而降低溶液的表面張力。本實驗利用懸垂液滴法觀測液滴撞擊前溶液的動態表面張力，並控制撞擊時溶液的表面張力，探討不同濃度的瓜爾豆膠溶液液滴在不同高度與固定高度下撞擊parafilm之潤濕行為。進而比較短時間與長時間下瓜爾豆膠分子吸附行為，觀察表面張力與黏度的混合效應，並由瓜爾豆膠溶液的研究試圖了解吸附性高分子的液滴撞擊行為。實驗觀察發現在未吸附瓜爾豆膠分子時，較高濃度的瓜爾豆膠液滴其黏滯力會抑制液滴回縮，亦即隨黏度提高，液滴回縮時間拉長，且造成高黏度瓜爾豆膠液滴較純水液滴更不易發生部分反彈(partial rebound)。在液滴界面上佈滿瓜爾豆膠分子時，液滴的回縮時間變更慢，液滴與基材接觸的面積與時間變得比未吸附前更大更長。
本研究第三部分探討界面活性劑在液滴撞擊的表面積變化，並提出相應的假設，得到表面積濃度與時間的關係。假設均勻與非均勻的表面濃度，計算其表面濃度變化，並針對TX-100與SDS在液滴撞擊，提出可能的解釋。

Wetting behavior of a droplet impinging on solid surfaces was discussed widely in academic fields for the past decade, and was widely used in many industrial processes; such as ink-jet printers, pesticide spraying on the leaf surface, 3D inkjet printing. Due to the short time range for the droplet impact process, a high-speed camera is needed on investigating of the drop impact process. In this study, a CCD camera with a 6,770 fps was used for taking both the side-view and top-view images.
The first part of this work is a study on the water droplet with a constant drop size (2.14mm diameter) impinging on PC substrates with various roughness in order to study the effect of roughness on the drop impact process. The surface morphology of the PC substrates was characterized using AFM. Furthermore, the relaxations of wetting diameter, contact angle and drop height were analyzed immediately after the impact of water drop on PC. A pinning phenomenon was observed in this part of study due to the existence of a random default on the PC surface.
The second part of this work is the drop impact of aqueous guar gum solutions on parafilm substrates. Guar gum solution is a non-Newtonian fluid with a shear thinning property. Guar gum molecules may absorb onto air-water interface and decrease the surface tension of the solution. The effects of viscosity and surface tension of guar gum solution on the drop impact of guar gun solutions on parafilm substrates were studied by using guar gum solution with various concentrations.
The third part of this work is a study on the relaxation of surface area of an impinging drop of surfactant solutions. The change of surface area for the drop immediately after the impact was analyzed in detail. The surface tension and the surface concentration of surfactant were then estimated during the drop impact process. Nonionic surfactant TX-100 and ionic surfactant SDS were used in this part of study.

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