Year: 2026
Type: preprint
Abstract: Bulk nanobubbles have attracted considerable attention because of their reported long-term stability. Yet this apparent stability appears inconsistent with classical predictions based on the Young–Laplace equation, and despite extensive theoretical and experimental studies, the underlying molecular mechanisms responsible remain unresolved. In this work, molecular dynamics simulations are used to evaluate the pressure–radius relationship for bulk nanobubbles and to investigate origins for possible deviations from classical Young–Laplace behaviour. Methodological aspects, including appropriate treatment of short-range interactions and determination of bulk liquid pressure in nanobubble systems, are also examined and validated. Comparisons reveal that cutoff-based approaches for short-range interactions introduce significant errors in the system pressure, whereas the Particle–Mesh Ewald method provides an accurate and computationally efficient alternative. We confirm that the system-averaged virial pressure rigorously corresponds to the bulk-liquid pressure for nanobubble systems. Pressure–radius analyses of empty nanobubbles in water and cyclopentane systems using the equimolar radius yield a description consistent with Young–Laplace behaviour when curvature-dependent corrections to the surface tension (i.e. the Tolman length) are accounted for. In water, the pressure contribution due to interfacial dipole polarization was found to be small. Accounting for the pressure (or density) dependence of the surface tension was shown to dramatically impact estimates for the Tolman length in cyclopentane. These results establish a consistent molecular simulation framework for further investigations of nanobubble stability and provide new insights into the roles of curvature, interfacial polarization, and liquid properties in determining mechanical equilibrium in nanobubbles.
Source: ChemRxiv
Institution: University of Calgary
Language: English
Subfield: Filtration and Separation
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7208755049