Sustainability of superhydrophobicity under pressure

• Published in: Physics of fluids (1994) 2012-11, Vol.24 (11)
• Main Authors: SAMAHA, Mohamed A, VAHEDI TAFRESHI, Hooman, GAD-EL-HAK, Mohamed
• Format: Article
• Language: English
• Subjects: Chaotic flows; drag reduction; Coatings; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deformation; material flow; Drag reduction; Electrospinning; Exact sciences and technology; Hydrophobicity; Hydrostatic pressure; Longevity; Physics; Rheology; Solid-fluid interfaces; Submerged; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Sustainability; Wetting
• ISSN: 1070-6631; 1089-7666
• DOI: 10.1063/1.4766200

Prior studies have demonstrated that superhydrophobicity of submerged surfaces is influenced by hydrostatic pressure and other environmental effects. Sustainability of a superhydrophobic surface could be characterized by both how long it maintains the trapped air in its surface pores, so-called "longevity," and the pressure beyond which it undergoes a global wetting transition, so-called "terminal pressure." In this work, we investigate the effects of pressure on the performance of electrospun polystyrene fibrous coatings. The time-dependent hydrophobicity of the submerged coating in a pressure vessel is optically measured under elevated pressures. Rheological studies are also performed to determine the effects of pressure on drag reduction and slip length. The measurements indicate that surface longevity exponentially decays with increasing pressure in perfect agreement with the studies reported in the literature at lower pressures. It is found, however, that fibrous coatings could resist hydrostatic pressures significantly higher than those of previously reported surfaces. Our observations indicate that superhydrophobic fibrous coatings could potentially be used for underwater applications.