Superhydrophobicity: Cavity growth and wetting transition
2015 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 448, 482-491 p.Article in journal (Refereed) Published
We show by using AFM colloidal probe microscopy (combinations of hydrophobic/superhydrophobic as probe/surface) that superhydrophobicity displays a set of specific events when compared with hydrophobicity. Both attraction (due to capillary and wetting forces) and repulsion (most likely due to repelling air/vapor layers or micro-/nanobubbles) occur upon approach and when surfaces are pulled apart both shorter range (50-100. nm or more) and longer range (several micrometers) attractive forces are displayed. The interaction is explained by forces generated through the formation of air and water vapor cavities, in the shorter-range (<50. nm) case maintaining a constant volume of the cavity, in agreement with calculation of capillary forces, and in the longer-range (<1. μm) case through access of air to the cavity, in agreement with thermodynamics of cavity growth. An added sodium dodecyl sulphate surfactant gave a partially reversible wetting transition and reduced the longer-range interaction to shorter-range, suggesting a transfer from the Cassie-Baxter to the Wenzel wetting regime. The findings would be of interest in development of practical applications, such as for anti-soiling, anti-icing, protection of electrical components and for extreme water-repellency in paper and textiles.
Place, publisher, year, edition, pages
2015. Vol. 448, 482-491 p.
Atomic force microscopy, Cavitation, Superhydrophobicity, Surface forces, Surfactant, Wetting, Hydrophobicity, Probes, Surface active agents, Thermodynamics, Attractive force, Electrical components, Longer-range interaction, Reversible wetting, Sodium dodecyl sulphate, Wetting transitions, dodecyl sulfate sodium, silica nanoparticle, Article, atmosphere, contact angle, geometry, hydrodynamics, microscopy, priority journal, scanning electron microscopy, water vapor
IdentifiersURN: urn:nbn:se:kth:diva-167704DOI: 10.1016/j.jcis.2015.02.054ISI: 000360592100058PubMedID: 25771290ScopusID: 2-s2.0-84924566069OAI: oai:DiVA.org:kth-167704DiVA: diva2:815933
QC 201506022015-06-022015-05-222015-10-05Bibliographically approved