亲/疏水表面上液滴接触角滞后的研究---Ⅱ.液滴移动推动力及前进角/后退角计算式
首发时间:2012-02-08
摘要:表面上液滴欲移动时所表现出的滞后现象尚未在理论上得到完全解决,其中液滴所受到的推动力的分析和计算是定量描述此滞后现象的关键问题之一。本文根据理论推导和Wilhelmy法所测得的实验数据,分析得到了液滴在前进角和后退角状态时所受到的推动力。由液滴在临界状态时的受力平衡,分别推导出了亲/疏水表面上前进角和后退角的理论表达式,并结合实验数据对理论表达式进行了验证。结果表明:接触角滞后与表面结构参数和界面性质有关,当且仅当平衡接触角是0 或180 时接触角滞后才不存在。由理论公式可以预测出表面上液滴的前进角和后退角,对于制备低接触角滞后的亲/疏水表面具有指导作用。
关键词: 推动力 前进角 后退角 接触角滞后 Wilhelmy法
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Research on contact angle hysteresis of droplet on hydrophilic and hydrophobic surface---Ⅱ. Driving force of moving droplet and theoretical formulas of advancing and receding contact angle
Abstract: The hysteresis phenomenon of droplet moving on surface has not yet been fully solved in theory, and the analysis and calculation of the driving force of a droplet is one of the key points to quantitatively describe the hysteresis phenomenon. According to the theoretical derivation and Wilhelmy experiment data, the driving force of a droplet on the state of advancing contact angle (ACA) and receding contact angle (RCA) were analyzed. And based on the force balance of the droplet in critical condition, the theoretical formulas of ACA and RCA were derived for hydrophilic and hydrophobic surfaces. The calculation results of ACA and RCA are consistent in general with experimental data. It is indicated that contact angle hysteresis (CAH) depends on both surface topography and interface chemical property, CAH does not exist only when equilibrium contact angle is 0 or 180 . The theoretical formulas can be used to predict both ACA and RCA and have instructive effect on designing hydrophilic and hydrophobic surfaces with low CAH .
Keywords: driving force advancing contact angle receding contact angle contact angle hysteresis Wilhelmy method
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亲/疏水表面上液滴接触角滞后的研究---Ⅱ.液滴移动推动力及前进角/后退角计算式
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