Contact Line Dynamics in Nanoparticle-Laden Droplets: Insights from Molecular Dynamics Simulations

Nanoparticle-laden droplets are central to advanced materials processing, including directed self-assembly and thin film fabrication. Control of deposition patterns requires understanding the liquid/solid/vapor three-phase contact line dynamics during droplet spreading and evaporation. Here, molecular dynamics simulations are used to investigate particle-induced spreading kinetics in nanosuspension droplets on solid substrates. We quantify the effects of nanoparticle size and concentration on spreading kinetics and transient droplet morphology, with emphasis on force distributions near the contact line. Results show that nanoparticles promote self-pinning through local structural jamming and enhanced resistance to motion, while depinning occurs when capillary forces exceed particle–substrate adhesion. By tuning the interaction strength between entrained particles and the substrate, wetting behavior transitions from rapid spreading to complete arrest. These results provide molecular-level insight into dynamic wetting in complex fluids and establish design guidelines for controlling nanoparticle deposition in surface engineering applications.