Contact-angle hysteresis on super-hydrophobic surfaces

G. McHale, N. J. Shirtcliffe, M. I. Newton

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The relationship between perturbations to contact angles on a rough or textured surface and the superhydrophobic enhancement of the equilibrium contact angle is discussed theoretically. Two models are considered. In the first (Wenzel) case, the super-hydrophobic surface has a very high contact angle and the droplet completely contacts the surface upon which it rests. In the second (Cassie-Baxter) case, the super-hydrophobic surface has a very high contact angle, but the droplet bridges across surface protrusions. The theoretical treatment emphasizes the concept of contact-angle amplification or attenuation and distinguishes between the increases in contact angles due to roughening or texturing surfaces and perturbations to the resulting contact angles. The theory is applied to predicting contact-angle hysteresis on rough surfaces from the hysteresis observable on smooth surfaces and is therefore relevant to predicting roll-off angles for droplets on tilted surfaces. The theory quantitatively predicts a "sticky" surface for Wenzel-type surfaces and a "slippy" surface for Cassie-Baxter-type surfaces.
Original languageEnglish
Pages (from-to)10146-10149
Number of pages4
JournalLangmuir
Volume20
Issue number23
DOIs
Publication statusPublished - 1 Nov 2004

Keywords / Materials (for Non-textual outputs)

  • water repellent
  • Wenzel
  • Cassie
  • rough
  • contact angle
  • hysteresis

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