https://scholars.lib.ntu.edu.tw/handle/123456789/62596
標題: | 親疏水性表面接觸角與線張力之研究 The Study of the Contact Angle and Line Tension at a Heterogeneous Surface Consisting of Alternating and Parallel Hydrophobic/Hydrophilic Stripes |
作者: | 梁孟堯 Liang, Meng-Yao |
關鍵字: | 微觸印刷;前進角;三相線;自聚性單分子膜;線張力;micro-contact printing;advancing contact angle;three-phase contact line;self-assembled monolayers;line tension | 公開日期: | 2006 | 摘要: | 藉由量測水滴在特定基材表面上的液滴直徑與前進角,代入modified Young’s equation導出的關係式,可求得此表面的線張力。本研究利用這個方法得到的線張力值為負號且大小都是10-6 J/m。本研究利用微觸印刷在基材表面製備親疏水性相間的自聚性單分子膜,探討當線寬變小時線張力對前進角造成的影響。當液滴三相線前進方向平行於親疏水相間直條紋時,三相線不扭曲,可以用Cassie equation (θC)來描述;當液滴三相線前進方向垂直於親疏水相間直條紋時,三相線會產生扭曲,可以用modified Cassie equation (θMC)來描述。矽烷分子在矽基材上形成親疏水性表面時,其前進角都偏大且隨著線寬變小時並沒有呈現明顯趨勢。這是因為矽烷分子在微觸印刷過程中容易堆積成多層分子膜。使用硫醇分子在金基材上形成親疏水性表面,我們求得的負的線張力值會讓在相同線寬下,θMC<θC。而隨著線寬變小前進角會跟著下降,θMC:79°(2μm) →62°(0.6μm) →54°(0.4μm)。金基材較大的表面粗糙度使得本研究的前進角實驗值都偏小。而使用光學顯微鏡可觀察到三相線的扭曲現象,但並非modified Cassie equation中假設的扭曲成半圓形。 Measuring the droplet diameter and advancing contact angle of water on the substrate, we can calculate the line tension of this surface by using the relation derived from modified Young’s equaton. The values of line tension in this experiment were all negative and of the order of 10-6 J/m. When a droplet laid on a specific surface consisting of alternating and parallel hydrophobic and hydrophilic stripes, while the three-phase contact line is parallel to the stripe, the line will be smooth and can be portrayed by Cassie equation(θC); while the three-phase contact line is normal to the stripe, the line will be contorted and can be described by modified Cassie equation(θMC). We prepared the alternating and parallel hydrophobic and hydrophilic self-assembled monolayers on the substrate by using the micro-contact printing. In case of silane on silicon substrate, advancing contact angle values were larger and had no tendency with decreasing line width. Because we found that silane are easy to pile up in course of micro-contact printing. In case of thiol on gold substrate, the negative line tension value would let θMC<θC, and advancing contact angle decreases with decreasing line width, θMC:79°(2μm) →62°(0.6μm) →54°(0.4μm). Gold substrate with larger surface roughness let advancing contact angle values were smaller in this experiment. We observed the contortion of the three-phase contact line with optical microscope, the situation was not agreed with the semi-circle assumed in the modified Cassie equation. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/52327 | 其他識別: | zh-TW |
顯示於: | 化學工程學系 |
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ntu-95-R93524004-1.pdf | 23.53 kB | Adobe PDF | 檢視/開啟 |
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