Nucleation processes of nanobubbles at a solid/water interface

Abstract

Experimental investigations of hydrophobic/water interfaces often return controversial results, possibly due to the unknown role of gas accumulation at the interfaces. Here, during advanced atomic force microscopy of the initial evolution of gas-containing structures at a highly ordered pyrolytic graphite/water interface, a fluid phase first appeared as a circular wetting layer ~0.3 nm in thickness and was later transformed into a cap-shaped nanostructure (an interfacial nanobubble). Two-dimensional ordered domains were nucleated and grew over time outside or at the perimeter of the fluid regions, eventually confining growth of the fluid regions to the vertical direction. We determined that interfacial nanobubbles and fluid layers have very similar mechanical properties, suggesting low interfacial tension with water and a liquid-like nature, explaining their high stability and their roles in boundary slip and bubble nucleation. These ordered domains may be the interfacial hydrophilic gas hydrates and/or the long-sought chemical surface heterogeneities responsible for contact line pinning and contact angle hysteresis. The gradual nucleation and growth of hydrophilic ordered domains renders the original homogeneous hydrophobic/water interface more heterogeneous over time, which would have great consequence for interfacial properties that affect diverse phenomena, including interactions in water, chemical reactions, and the self-assembly and function of biological molecules.

Initial growth dynamics of 10 nm nanobubbles in the graphene liquid cell

“…Chan et al used total internal reflection fluorescence microscopy to measure the growth of the height of pinned nanobubble which is initiated by the coalescence of the two nanobubbles (Chan et al 2015). The atomic force microscopic study also obtained the successive height profiles of growing nanobubble and resolved the existence of the circular wetting layer which initiates the growth of nanobubble (Fang et al 2016). These nanobubbles can be stabilized by the surface pinning of three phase contact line Zhang 2013, 2014;Tan et al 2017;Weijs and Lohse 2013;Lohse and Zhang 2015a, b).…”

On the mechanism of automated fizzy extraction

“…6). These microbubbles further grow due to absorption of dissolved gas (Fang et al, 2016), and coalesce with other (micro)bubbles (Chaudhari & Hofmann, 1994). Previously, we showed that increasing carbon dioxide pressure (0-150 kPa) during saturation leads to increased analyte peak areas during FE (Chang & Urban, 2016).…”

Nanobubbles Form at Active Hydrophobic Spots on the Luminal Aspect of Blood Vessels: Consequences for Decompression Illness in Diving and Possible Implications for Autoimmune Disease—An Overview

“…Bulavin et al ( 2014 ) suggested that a vapor–liquid phase transition occurs at low temperatures, due to repulsive forces which increase the chemical potential of the molecules in the liquid phase near the hydrophobic surface. Fang et al ( 2016 ) presented the time scale of nanobubble formation with intricate interplay among gas molecules, water, and hydrophobic solids. Whatever the mechanism underlying the nucleation and stabilization of nanobubbles, final doubts regarding an artifact of the atomic force microscopy were removed with optical confirmation (Karpitschka et al, 2012 ).…”

“…One of the commonly suggested explanations for the relief obtained using these methods is elimination or dislodgment of some of the gas micronuclei from the surface of blood vessels. According to Fang et al ( 2016 ), it takes somewhat more than 2 h for nanobubbles to reappear. Thus, pretreatment was carried out within the time scale required to preempt the renewal of nanobubbles, and consequently the development of gas micronuclei.…”