Contact Line Pinning on Microstructured Surfaces for Liquids in the Wenzel State

Pontus S. H. Forsberg, Craig Priest, Martin Brinkmann, Rossen Sedev, John Ralston

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104 Citations (Scopus)

Abstract

The wettability of surfaces microstructured with square pillars was studied, where the static advancing contact angle on the planar surface was 72°. We observed elevated advancing angles (up to 140°) on these structures for droplets in the Wenzel state. No air was trapped in the structured surfaces beneath the liquid, ruling out the well-known Lotus leaf effect. Instead, we show that the apparent hydrophobicity is related to contact line pinning at the pillar edges, giving a strong dependence of wetting hysteresis on the fraction of the contact line pinned on pillars. Simulating the contact line pinning on these surfaces showed similar behavior to our measurements, revealing both strong pinning at the edges of the pillars as well as mechanistic details.
Original languageEnglish
Pages (from-to)860-865
JournalLangmuir
Volume26
Issue number2
Early online date24 Aug 2009
DOIs
Publication statusPublished - 19 Jan 2010
Externally publishedYes

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