Structure-dependent nanobubble dynamics in multi-nanoparticle systems

The spatial distribution of nanoparticles is hypothesized to be a critical, tunable parameter governing nanobubble dynamics and interfacial heat transfer. We propose that multi-nanoparticle systems, unlike isolated particles that were the focus of prior studies, can leverage collective effects to lower the energy barrier for nucleation, modulate nanobubble growth, and delay structural failure, thereby offering a pathway to optimize thermal processes in nanomedicine and nanoscale energy transfer.

Molecular dynamics simulations were employed to investigate this hypothesis, using liquid argon as the working medium. We systematically studied four gold nanoparticle configurations: a single particle, a linear particle pair, a planar triangular cluster of three particles, and a tetrahedral cluster of four particles, under three distinct heating conditions: constant total heating power, constant per-particle power, and variable power. A grid-based density method was developed to quantify nanobubble volume in these asymmetric systems accurately.

Multi-nanoparticle systems generate larger nanobubbles and significantly delay melting compared to a single particle, due to spatial energy dispersion and cooperative heating effects. Under identical per-particle heating, clusters reduce the effective spinodal temperature, promoting nucleation. The presence of a nanobubble drastically increases the interfacial thermal resistance, creating a thermal feedback loop that accelerates nanoparticle heating. This study establishes nanoparticle architecture as a fundamental design parameter for controlling vapor generation and heat transfer in colloidal system, which is of high importance for optimizing nanoparticle related heating systems.