Nanobubbles and the hydrophobic attraction

Force measurements with the atomic force microscope: Technique, interpretation and applications

“…Neutron [547] and X-ray [548] reflectivity experiments confirmed the observed reduced density of water at the interface, while experiments with an ellipsometer excluded nanobubbles on silanated silica [549]. There is now strong evidence, that bridging bubbles contribute to the long-range hydrophobic attraction in many experiments [495] but the whole hypothesis and the effect of nanobubbles are still being debated [550].…”

“…Hydrophobic surfaces in water attract each other [494,495]. This attraction is called hydrophobic interaction.…”

Interaction forces between particles stabilized by a hydrophobically modified inulin surfactant

“…On withdrawal, a very strong attraction is observed followed by a jump out to 150 nm from the surface. Figure 3 also The origin of such interaction are not entirely clear, but some authors attributed these forces to the presence of small air bubbles nucleated on the hydrophobic surface [30], which, when it comes in contact with another hydrophobic surface caused a bridging of the nanobubbles, drawing the two surfaces together .…”

Colloidal crystals and water: Perspectives on liquid–solid nanoscale phenomena in wet particulate media

“…Annuli are also observed between hydrophobic polystyrene spheres (Figure 8c; see Figure 13b also), which indicates close −at least, closer− contact when dealing with hydrophobic surfaces. The formation of annuli (with a wide central aperture) rather than necks with vanishing thickness at the center suggests the occurrence of an air meniscus (a bubble), instead of a water one, formed at the hydrophobic surface [125]. The set-up (capillary evaporation) and characteristics of such nanobubbles are enigmatic [126], and they have been long proposed to elucidate the origin of long-range hydrophobic forces [125].…”

“…The formation of annuli (with a wide central aperture) rather than necks with vanishing thickness at the center suggests the occurrence of an air meniscus (a bubble), instead of a water one, formed at the hydrophobic surface [125]. The set-up (capillary evaporation) and characteristics of such nanobubbles are enigmatic [126], and they have been long proposed to elucidate the origin of long-range hydrophobic forces [125]. Hence, the simple one-pulse CVD technique would provide an easy approach to investigate this important surface science topic which remains incompletely resolved.…”