Formation of surface nanobubbles and universality of their contact angles: A molecular dynamics approach

TL;DR

This study uses molecular dynamics simulations to explore the formation and contact angles of surface nanobubbles, revealing their dependence on gas solubility and solid attraction, and suggesting stabilization mechanisms.

Contribution

It introduces a molecular dynamics model for nanobubbles, demonstrating how gas-solid interactions influence their formation and contact angle universality.

Findings

Nanobubbles form at low gas solubility levels.

Gas layer formation explains contact angle universality.

Nanobubbles dissolve quickly under equilibrium conditions.

Abstract

We study surface nanobubbles using molecular dynamics simulation of ternary (gas, liquid, solid) systems of Lennard-Jones fluids. They form for sufficiently low gas solubility in the liquid, i.e., for large relative gas concentration. For strong enough gas-solid attraction, the surface nanobubble is sitting on a gas layer, which forms in between the liquid and the solid. This gas layer is the reason for the universality of the contact angle, which we calculate from the microscopic parameters. Under the present equilibrium conditions the nanobubbles dissolve within less of a microsecond, consistent with the view that the experimentally found nanobubbles are stabilized by a nonequilibrium mechanism.