Evaporation kinetics and interfacial thermal transport of nanodroplets on hybrid wettability surfaces

• Evaporation modes and energy transport on hybrid wettability surfaces are identified. • Molecular-level validation of SRT and HKS for droplet evaporation is provided. • Optimal hydrophilic fraction minimizes thermal resistance and maximizes heat flux. Heterogeneous surfaces are widely employed to regulate droplet evaporation, however, the microscopic mechanisms of interfacial energy and mass transport remain unclear. Molecular dynamics (MD) simulations are conducted to further investigate the evaporation dynamics and interfacial heat and mass transfer of nanoscale droplets on hybrid-wettability surfaces, including functionally graded wettability (FGW) and patterned wettability. Results reveal that at the same wettability ratio, droplet evaporation on patterned surfaces proceeds through mixed, constant contact radius (CCR), and fragmentation–mixed modes, whereas FGW surfaces exhibit sequential CCR, alternating constant contact angle (CCA)–CCR. Patterned surfaces induce mixed to fragmentation evaporation modes and promote stronger local coupling between heat and mass transfer at the three-phase contact line, resulting in more efficient interfacial evaporation compared with FGW surfaces. The interfacial mass transfer rate on hybrid-wettability surfaces increases with temperature difference and hydrophilic fraction. Verification using the Hertz–Knudsen–Schrage equation and Statistical Rate Theory reveals that both models can accurately predict the evaporation mass flux under different temperature differences, elucidating the microscopic mechanism of interfacial mass transfer during evaporation on hybrid-wettability surfaces. From a heat transfer perspective, hybrid-wettability surfaces show the lowest interfacial thermal resistance and highest average heat flux at a hydrophilic fraction of 75%. At the same wettability ratio, the patterned surface can reduce the thermal resistance by up to 49.96% compared to the FGW surface, indicating that the periodic structure significantly enhances interfacial energy coupling and heat transfer efficiency. Moreover, increasing the hydrophilic fraction leads to a higher overlap in the vibrational density of states between the solid and near-surface atoms.