Molecular modelling of active oil droplet propulsion: Insights from dissipative particle dynamics simulation.

This study employed dissipative particle dynamics (DPD) simulations to investigate the self-propelled motion of oil droplets in water–oil–surfactant systems. It is the first attempt to replicate self-propulsion models of oil droplets at the molecular level, contrasting previous simulations focused on Brownian motion and hydrodynamic behaviour of colloidal particles. The DPD model reproduced droplet propulsion and visualised internal Marangoni flow, showing that larger droplet radii and greater interfacial tension differences increase propulsion speeds. Additionally, surfactants with stronger oil–oil repulsion enhanced propulsion speed, suggesting that surfactant-induced local structures are crucial for the self-propulsion mechanism. • DPD simulations reproduced self-propelled motion of oil droplets at the molecular level. • Larger oil droplet radii resulted in proportional increases in propulsion velocity. • A 2% interfacial tension difference significantly increased propulsion speed. • Surfactant structure impacted oil–oil interactions, influencing propulsion velocity. • The DPD approach explained molecular mechanisms in non-equilibrium active systems. [ABSTRACT FROM AUTHOR]