3 years ago

Octagonal Wetting Interface Evolution of Evaporating Saline Droplets on a Micropyramid Patterned Surface

Octagonal Wetting Interface Evolution of Evaporating Saline Droplets on a Micropyramid Patterned Surface
Fei Duan, Junheng Ren, Xin Zhong, Kian-Soo Ong, Mingfeng Lin, Karen Siew Ling Chong
Textured surfaces have been extensively employed to investigate the dynamics, wetting phenomena, and shape of liquid droplets. Droplet shape can be controlled via the manipulation of topographic or chemical heterogeneity of a solid surface by anchoring the three-phase line at specific sites. In this study, we demonstrate that droplet shape on a topographically patterned surface can be modified by varying the concentration of salt potassium chloride (KCl) in the droplet solution. It is found that at the beginning of evaporation the octagonal shape of the solid–liquid interface is changed to a rectangle with corners cut upon increasing the salt concentration. Such a variation in the solid–liquid interface versus the salt concentration is explained by the analysis of free energy difference. It indicates that the increases in solid–liquid and liquid–vapor surface tensions by raising the salt concentration result in a favored extension of the three-phase line intersecting the micropyramid bottom sides than the counterpart intersecting the micropyramid diagonal edges. The saline droplets experience a pinning stage at first and a depinning one afterward. The onset of depinning is delayed, and at which the instantaneous contact angle is larger upon raising the salt concentration. The three-phase line which intersects the micropyramid diagonal edges recedes ahead of the one along the micropyramid bottom sides, making the octagonal wetting interface evolve toward a circle. A close view at the droplet edge indicates that the three-phase line repeats “slow slip–rapid slip” across row by row of micropyramids during the depinning stage.

Publisher URL: http://dx.doi.org/10.1021/acsami.7b07533

DOI: 10.1021/acsami.7b07533

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.