Many-body dissipative particle dynamics study of mesoscale liquid film dewetting: Formation of heteromorphic droplets

The dewetting behavior of nano-liquid films, strongly influenced by film thickness and substrate wettability, plays a key role in micro- and nano-device performance but remains inadequately described by traditional continuum models. In this study, a many-body dissipative particle dynamics (MDPD) framework is employed to construct a mesoscale liquid film dewetting model that bridges nanoscopic interactions and macroscopic statistical behavior. Dewetting kinetics are systematically investigated under varying film thicknesses and interfacial conditions, and five representative dewetting modes are identified: spinodal dewetting, nucleation dewetting, stable dewetting, heteromorphic-droplet dewetting, and stable films. Through energy and molecular force analysis, droplet pattern formation is found to comprise three stages: accelerated contraction, decelerated contraction, and droplet dissipation. In ultrathin films, the initial instability is mainly governed by thickness-dependent interfacial forces, whereas the later-stage retraction and droplet relaxation are influenced by curvature-dependent capillary effects. To rationalize multiple dewetting morphologies, the classical disjoining-pressure model is extended within the MDPD framework by introducing an exponential structural-force term, and the zero-crossings of the first derivative of the disjoining pressure are used as a semi-quantitative indicator for distinguishing dewetting regimes. Overall, nano-liquid film dewetting originates from the balance between internal molecular forces and substrate-induced interfacial forces. Based on this mechanism, a mesoscopic dewetting phase diagram is established, linking substrate wettability and film thickness to distinct dewetting morphologies. These findings provide insight into nano-film dewetting and guidance for wetting control and surface engineering in micro- and nano-device applications.