Contact-angle hysteresis on super-hydrophobic surfaces

McHale, Glen, Shirtcliffe, Neil and Newton, Michael (2004) Contact-angle hysteresis on super-hydrophobic surfaces. Langmuir, 20 (23). pp. 10146-10149. ISSN 0743-7463

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Abstract

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.

Item Type:	Article
Uncontrolled Keywords:	water repellent, Wenzel, Cassie, rough, contact angle, hysteresis
Subjects:	F100 Chemistry F200 Materials Science F300 Physics
Department:	Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User:	Glen McHale
Date Deposited:	23 Aug 2012 13:59
Last Modified:	12 Oct 2019 19:06
URI:	http://nrl.northumbria.ac.uk/id/eprint/8337

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