Contact angles on heterogeneous surfaces; a new look at Cassie's and Wenzel's laws

P. S. Swain; Reinhard Lipowsky

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arXiv · cond-mat/9809089

Contact angles on heterogeneous surfaces; a new look at Cassie's and Wenzel's laws

P. S. Swain·Reinhard Lipowsky

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Abstract

We consider a three dimensional liquid drop sitting on a rough and chemically heterogeneous substrate. Using a novel minimization technique on the free energy of this system, a generalized Young's equation for the contact angle is found. In certain limits, the Cassie and Wenzel laws, and a new equivalent rule, applicable in general, are derived. We also propose an equation in the same spirit as these results but valid on a more `microscopic' level. Throughout we work under the presence of gravity and keep account of line tension terms.

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P. S. Swain, Reinhard Lipowsky. 1998-12-21. Contact angles on heterogeneous surfaces; a new look at Cassie's and Wenzel's laws. https://arxiv.org/abs/cond-mat/9809089

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