Wetting on the Microscale: Shape of a Liquid Drop on a Microstructured Surface at Different Length Scales

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• 作者：Periklis Papadopoulos ; Xu Deng ; Lena Mammen ; Dirk-Michael Drotlef ; Glauco Battagliarin ; Chen Li ; Klaus M眉llen ; Katharina Landfester ; Aranzazu del Campo ; Hans-J眉rgen Butt ; Doris Vollmer
• 刊名：Langmuir
• 出版年：2012
• 出版时间：June 5, 2012
• 年：2012
• 卷：28
• 期：22
• 页码：8392-8398
• 全文大小：422K
• 年卷期：v.28,no.22(June 5, 2012)
• ISSN：1520-5827

文摘

Describing wetting of a liquid on a rough or structured surface is a challenge because of the wide range of involved length scales. Nano- and micrometer-sized textures cause pinning of the contact line, reflected in a hysteresis of the contact angle. To investigate contact angles at different length scales, we imaged water drops on arrays of 5 渭m high poly(dimethylsiloxane) micropillars. The drops were imaged by laser scanning confocal microscopy (LSCM), which allowed us to quantitatively analyze the local and large-scale drop profile simultaneously. Deviations of the shape of drops from a sphere decay at two different length scales. Close to the pillars, the amplitude of deviations decays exponentially within 1鈥? 渭m. The drop profile approached a sphere at a length scale 1 order of magnitude larger than the pillars鈥?height. The height and position dependence of the contact angles can be understood from the interplay of pinning of the contact line, the principal curvatures set by the topography of the substrate, and the minimization of the air鈥搘ater interfaces.