本實驗對於接觸角的遲滯現象進行深入的研究，使用傾斜板法來記錄液珠滑落前之前端與後端(下方與上方) 接觸角，其差異值即為此材質的遲滯角度。第一部分我們採用兩種材料(壓克力與銅片)來進行傾斜板的實驗，在相同的液珠體積之下製造兩種不同起始接觸角(前進角時與後退角)的液珠，並記錄下隨著傾斜角度而改變的液珠下方角度與上方角度；同樣的，將兩種材質浸泡在水中，在相同的氣泡體積之下製造兩種不同起始接觸角(前進角時與後退角)的氣泡。將壓克力與銅片傾斜時，可觀察到兩種不同的現象，分別是Advancing pinning與Receding pinning的潤濕行為。第二部份繼續使用傾斜板法，此時我們在一個壓克力上製造一個低遲滯的超疏水表面，並在此超疏水表面上製造一個較親水的缺陷，觀察此缺陷對於水珠的黏滯力與重力抗衡的情形。探討將液珠體積、缺陷的大小與形狀進行改變時，其臨界傾斜角(液珠的滑動角)的相對變化。在改變缺陷的大小發現，只有與重力滑落方向垂直之長度增加時，才會對於臨界傾斜角會有改變；進一步利用三角形的缺陷可加以驗證。Our experiment is to study the phenomenon of contact angle hysteresis by the inclined plate method. Two substrates (PMMA slice and cooper disc) are used. The front (downhill) and rear (uphill) contact angle of the droplet on the inclined substrate is recorded before the critical inclined angle is achieved where the droplet starts to slide down.At part 1, the droplets with different initial states (advancing angle and receding angle) are inclined until it slides away. We also immerse the substrated into water and two initial states of bubbles (advancing angle and receding angle) are operated similarly to the droplets. We can find out that the behavior of droplets and bubbles are alike and the advancing pinning and receding pinning phenomena can be generated based on “induced defect.”At part 2, we use PMMA to make a localized hydrophilic defect on a low hysteresis superhydrophobic surface in order to observe the behavior of adhesion pinning force against gravity force. The variation of droplet volume or defect size with the sliding angle is studied. When droplet slides, the uphill angle of the drop reduces to the receding angle of the defect. The magnitude of sliding angle grows approximately linearly with the pinning length, which is the contact line length on the defect and perpendicular to the sliding direction.
