Dynamic equilibrium Mechanism for Surface Nanobubble Stabilization

TL;DR

This paper proposes a dynamic equilibrium mechanism that explains the stability of surface nanobubbles on hydrophobic surfaces by balancing gas influx and outflux, predicting their size and formation thresholds.

Contribution

It introduces a novel theory of nanobubble stabilization based on continuous gas influx balancing Laplace-driven outflux, extending understanding beyond classical dissolution models.

Findings

Predicts equilibrium nanobubble radius as a function of surface properties.

Identifies conditions for nanobubble formation based on hydrophobicity and gas concentration.

Provides a theoretical framework for nanobubble stability in non-equilibrium conditions.

Abstract

Recent experiments have convincingly demonstrated the existence of surface nanobubbles on submerged hydrophobic surfaces. However, classical theory dictates that small gaseous bubbles quickly dissolve because their large Laplace pressure causes a diffusive outflux of gas. Here we suggest that the bubbles are stabilized by a continuous influx of gas near the contact line, due to the gas attraction towards hydrophobic walls (Dammer & Lohse, PRL96, 206101 (2006); Zhang {\it et al.}, PRL98, 136101 (2007); Mezger {\it et al.}, J.\ Chem. Phys. 128, 244705 (2008)). This influx balances the outflux and allows for a meta-stable equilibrium, which however vanishes in thermodynamic equilibrium. Our theory predicts the equilibrium radius of the surface nanobubbles, as well as the threshold for surface nanobubble formation as a function of hydrophobicity and gas concentration.