Effect of Micropillar Spacing and Temperature of Substrate on Contact Angle Dynamics
Effect of Micropillar Spacing and Temperature of Substrate on Contact Angle Dynamics
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微柱间距和基底温度对接触角动力学的影响
DOI：
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
K. Sefiane
中科院分区：
文献类型：
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作者：
Coinneach Mackenzie;G. Duursma;J. Christy;J. Terry;K. Sefiane
本文研究了沉积在结构化表面上的液滴的接触角动力学，并考察了基底微结构和温度对液滴接触角的影响。微结构由均匀尺寸的，不同的柱间距的立方体微柱构成的微制造。将液滴（体积为数十微升的数量级）沉积在这些表面上，并使用各种技术观察动态接触角。使用倾斜表面或通过注射器从水平液滴注射和抽吸流体来测量前进和后退接触角。这些表面上的液滴似乎主要处于Wenzel状态。接触角滞后作为柱间距或等效地表面粗糙度的函数而获得。推导了脱钉力与最大三相接触线之间的关系，发现在一定的微柱间距下，倾斜液滴沉积表面和均匀增加和减少液滴体积的方法都能得到相同的接触角滞后。然后使用加热的倾斜板评估温度的影响。发现接触角滞后随温度增加而增加。进一步的工作，以阐明这种依赖性的机制将进行。
ABSTRACT Contact angle dynamics of droplets deposited on a structured surface were studied in this work and the effects of substrate microstructure and temperature were investigated. Microstructures consisting of uniformly-sized, cubic micropillars with varying pillar spacings were constructed by microfabrication. Droplets (of the order of tens of microlitres in volume) were deposited on these surfaces and dynamic contact angles were observed using various techniques. Advancing and receding contact angles were measured using tilting of the surfaces or by injection and aspiration of fluid from a horizontal droplet by syringe. Droplets on these surfaces appeared to be mainly in the Wenzel state. Contact angle hysteresis was obtained as a function of pillar spacing or, equivalently, surface roughness. Depinning force was deduced and a linear dependence on maximal three phase contact line was found. The techniques of tilting the surface on which the droplet was deposited and uniformly increasing and reducing the volume of the droplet via the syringe both gave the same contact angle hysteresis for a given micropillar spacing. The effect of temperature was then assessed using a heated tilting plate. Contact angle hysteresis was found to increase with temperature. Further work to elucidate mechanisms governing this dependence will be undertaken.