Surface nanobubbles as a function of gas type

TL;DR

This study explores how different gases influence the formation and properties of surface nanobubbles on coated silicon, revealing gas-dependent nucleation behavior, an optimal temperature for formation, and the role of adsorbed gas molecules.

Contribution

It provides the first detailed experimental analysis of how gas type affects nanobubble nucleation, contact angle, and line tension on a specific substrate.

Findings

Nanobubble nucleation varies significantly with gas type.

Maximum nucleation occurs at around 35-40°C, weakly dependent on gas.

Line tension depends on gas type, averaging -0.8 nN.

Abstract

We experimentally investigate the nucleation of surface nanobubbles on PFDTS-coated silicon as a function of the specific gas dissolved in the water. In each case we restrict ourselves to equilibrium conditions ($c=100%$, $T_{liquid} = T_{substrate}$). Not only is nanobubble nucleation a strong function of gas type, but there also exists an optimal system temperature of $\sim 35-40\mathrm{^oC}$ where nucleation is maximized, which is weakly dependent on gas type. We also find that contact angle is a function of nanobubble radius of curvature for all gas types investigated. Fitting this data allows us to describe a line tension which is dependent on the type of gas, indicating that the nanobubbles are sat on top of adsorbed gas molecules. The average line tension was $\tau \sim -0.8 \mathrm{nN}$.