Why do pigeon feathers repel water? Hydrophobicity of pennae, Cassie-Baxter wetting hypothesis and Cassie-Wenzel capillarity-induced wetting transition

Edward Bormashenko, Yelena Bormashenko, Tamir Stein, Gene Whyman, Ester Bormashenko

Research output: Contribution to journalArticlepeer-review

203 Scopus citations

Abstract

Wetting of pigeon feathers has been studied. It was demonstrated that the Cassie-Baxter wetting regime is inherent for pigeon pennae. The water drop, supported by network formed by barbs and barbules, sits partially on air pockets. Small static apparent angle hysteresis justifies the Cassie-Baxter wetting hypothesis. A twofold structure of a feather favors large contact angles and provides its water repellency. Cassie-Wenzel transition has been observed under drop evaporation, when drop radius becomes small enough for capillarity-induced water penetration into the protrusions, formed by barbules.

Original languageEnglish
Pages (from-to)212-216
Number of pages5
JournalJournal of Colloid and Interface Science
Volume311
Issue number1
DOIs
StatePublished - 1 Jul 2007

Keywords

  • Apparent contact angle
  • Barbs
  • Barbules
  • Cassie-Baxter wetting regime
  • Cassie-Wenzel wetting transition
  • Contact angle hysteresis
  • Pigeon feather

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