Increased Stability and Size of a Bubble on a Superhydrophobic Surface

Abstract

Computational and theoretical models of millimeter-sized bubbles placed on upright hydrophobic and superhydrophobic surfaces are compared with experimental data here. Although the experimental data for a hydrophobic surface corroborated the computational and theoretical data, the case of a superhydrophobic surface showed the bubbles to be able to contain significantly larger volumes than predicted. This is attributed to the greater ability of the bubble contact line to advance compared with its tendency to detach from the surface because of buoyancy. We surmise that a static model therefore describes only an unstable equilibrium for these bubbles, which unless heavily isolated from external influences are more likely to assume a larger stable size.

Superwettability of Gas Bubbles and Its Application: From Bioinspiration to Advanced Materials

“…Air pockets captured in the nanostructure of the lotus leaf could easily coalesce with the air bubble, and the microstructure could provide enough space to form gas bridges for air-bubble spreading. [24] In fact, several insects hiding or hunting underwater exploit the property of superaerophilicity. [25][26][27][28][29] Water spiders…”

“…Thus, air is retained in their nano/microstructures. [24,35,36] Here, CAH is defined as the difference between the cosine of the maximum and minimum static contact angles on the uphill (θ max ) and downhill (θ min ) sides upon tilting the substrate at a particular angle. As gas bubbles come into contact with these superhydrophobic interfaces, air pockets captured in the microstructure could easily coalesce with the air bubbles and then lead to air-bubble spreading.…”

Glycerol–water sessile drop elongation on PTFE inclines in relation to biochemical applications

“…When immersed in water, SH surfaces have been shown to develop a stable thin film of air called a plastron [22,23]. Plastrons are also believed to be responsible for the ability of sessile bubbles to exist on the SH surfaces at volumes much larger than anticipated [24]. On non-SH PTFE, it is conceivable that regions of non-visible surface air entrapment may continue to exist even when the larger bubbles dissipate through diffusion [17].…”

Recent Progress in Fabricating Superaerophobic and Superaerophilic Surfaces

“…The derivation of bubble contact angle (θ b ) from Young's equation is possible by interchanging solid–liquid (γ sl ) and solid–vapor (γ sv ) surface tensions, followed by applying trigonometric relations. It is apparent from Equation that θ w and θ b are complementary to each other …”