Effect of Three-Phase Contact Line Topology on Dynamic Contact Angles on Heterogeneous Surfaces

Cassie−Baxter theory has traditionally been used to study liquid drops in contact with microstructured surfaces. The Cassie−Baxter theory arises from a minimization of the global Gibbs free energy of the system but does not account for the topology of the three-phase contact line. We experimentally...

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Bibliographic Details
Published in:Langmuir 2007-11, Vol.23 (23), p.11673-11676
Main Authors: Anantharaju, Neeharika, Panchagnula, Mahesh V, Vedantam, Srikanth, Neti, Sudhakar, Tatic-Lucic, Svetlana
Format: Article
Language:English
Subjects:
Chemistry
Colloidal state and disperse state
Exact sciences and technology
General and physical chemistry
Surface physical chemistry
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Summary:Cassie−Baxter theory has traditionally been used to study liquid drops in contact with microstructured surfaces. The Cassie−Baxter theory arises from a minimization of the global Gibbs free energy of the system but does not account for the topology of the three-phase contact line. We experimentally compare two situations differing only in the microstructure of the roughness, which causes differences in contact line topology. We report that the contact angle is independent of area void fraction for surfaces with microcavities, which correspond to situations when the advancing contact line is continuous. This result is in contrast with Cassie−Baxter theory, which uses area void fraction as the determining parameter, regardless of the type of roughness.
ISSN:0743-7463
1520-5827
DOI:10.1021/la702023e