Nanobubble Dynamics in Aqueous Surfactant Solutions Studied by Liquid-Phase Transmission Electron Microscopy

Abstract

Nanobubbles have attracted considerable attention in various industrial applications due to their exceptionally long lifetime and their potential as carriers at the nanoscale. The stability and physiochemical properties of nanobubbles are highly sensitive to the presence of surfactants that can lower their surface tension or improve their electrostatic stabilization. Herein, we report real-time observations of the dynamic behaviors of nanobubbles in the presence of soluble surfactants. Using liquid-phase transmission electron microscopy (TEM) with multi-chamber graphene liquid cells, bulk nanobubbles and surface nanobubbles were observed in the same imaging condition. Our direct observations of nanobubbles indicate that stable gas transport frequently occurs without interfaces merging, while a narrow distance is maintained between the interfaces of interacting surfactant-laden nanobubbles. Our results also elucidate that the interface curvature of nanobubbles is an important factor that determines their interfacial stability.