Geometric Interpretation of Surface Tension Equilibrium in Superhydrophobic Systems

Entropy

Michael Nosonovsky¹  Rahul Ramachandran² 

[1] Department of Mechanical Engineering, University of Wisconsin-Milwaukee, 3200 N Cramer St, Milwaukee, WI 53211, USA; E-Mail

关键词: surface tension;    entropic force;    superhydrophobicity;    Neumann’s triangle;    Antonoff’s rule;    hysteresis;   

DOI  :  10.3390/e17074684

来源: mdpi

【 摘 要 】

Surface tension and surface energy are closely related, although not identical concepts. Surface tension is a generalized force; unlike a conventional mechanical force, it is not applied to any particular body or point. Using this notion, we suggest a simple geometric interpretation of the Young, Wenzel, Cassie, Antonoff and Girifalco–Good equations for the equilibrium during wetting. This approach extends the traditional concept of Neumann’s triangle. Substances are presented as points, while tensions are vectors connecting the points, and the equations and inequalities of wetting equilibrium obtain simple geometric meaning with the surface roughness effect interpreted as stretching of corresponding vectors; surface heterogeneity is their linear combination, and contact angle hysteresis is rotation. We discuss energy dissipation mechanisms during wetting due to contact angle hysteresis, the superhydrophobicity and the possible entropic nature of the surface tension.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland