Does the contact angle hysteresis control the droplet shapes on cylindrical fibers?
Does the contact angle hysteresis control the droplet shapes on cylindrical fibers?
复制标题
接触角滞后是否控制圆柱形纤维上的液滴形状？
DOI：
10.1016/j.colsurfa.2023.131435
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Kornev, Konstantin G.
中科院分区：
文献类型：
--
作者：
Sun, Yueming;Kornev, Konstantin G.
假设圆柱形纤维上的平衡液滴分为两类：桶形液滴和蛤壳形液滴。在桶形液滴中，液体完全包覆纤维，液滴形成两条边界接触线。在蛤壳状液滴中，液体下方的部分纤维表面保持干燥，只有一条边界接触线。到目前为止，从一种形状到另一种形状的过渡是通过忽略接触角滞后来预测的。采用按需滴加技术进行了一系列新的实验，以分析液滴的形状。现有的理论无法解释所获得的数据。我们假设，形态蛤壳桶过渡液滴显着依赖于液滴形成的方法，并在很大程度上控制的接触角滞后。实验为了验证这一假设，我们研究了两种液滴形成的情况。在第一种情况下，十六烷液滴是通过在纤维上印刷较小的液滴而在纤维上生长的。在第二种情况下，由于Plateau-Rayleigh不稳定性，液滴是由甘油涂层膜自发形成的。为了获得一系列的接触角，一组不同的硅烷吸附在纤维表面上。结果-结果表明，对于小接触角（< 40°）和小接触角滞后，这两种方法的液滴形成导致相同的理论上可解释的条件蛤壳桶过渡。随着接触角的增加和滞后现象变得明显，蛤壳-桶形转变的条件变得显著依赖于液滴形成的方法。我们发现，对于大于60°的接触角，不存在桶形液滴。实验结果记录在一组描述蛤壳桶过渡的图表中。这些图表可用于不同的工程应用。
Hypothesis Equilibrium droplets on cylindrical fibers are divided into two classes: barreled and clamshell droplets. In the barreled droplet, the liquid body fully envelops the fiber, and the drop forms two boundary contact lines. In the clamshell droplets, some fiber surface under the liquid body remains dry and only one boundary contact line exists. So far, the transition from one shape to the other was predicted by ignoring the contact angle hysteresis. A new series of experiments using drop-on-demand technology were conducted to analyze the shape of droplets. The existing theory cannot explain the obtained data. We hypothesized that the morphological clamshell-barrel transition of droplets significantly depends on the method of drop formation and is largely controlled by the contact angle hysteresis. Experiment To test this hypothesis, we investigated two scenarios of drop formation. In the first scenario, the hexadecane drop was growing on the fiber by printing smaller drops on it. In the second scenario, the drop was formed spontaneously from a coating glycerol film due to the Plateau-Rayleigh instability. To obtain a range of contact angles, a set of different silanes were adsorbed on the fiber surfaces. Findings The results showed that for small contact angles (< 40°) and small contact angle hysteresis, both methods of drop formation led to the same theoretically explainable conditions for clamshell-barrel transition. As the contact angle increases and hysteresis becomes appreciable, the conditions for clamshell-barrel transition become significantly dependent on the method of drop formation. We discovered that no barreled droplets exist for contact angles greater than 60°. The experimental results were documented in a set of diagrams describing the clamshell-barrel transitions. These diagrams can be used in different engineering applications.