Unravelling the Effect of Dynamic Loading on the Infiltration of Water into Hydrophobic Nanopores.

Understanding the liquid infiltration subjected to external loadings with various rates is of critical importance to the design of nanofluidics-based anti-impact systems. In the present work, nonequilibrium molecular dynamics were used to probe water intrusion into hydrophobic nanopores under varied loading rates. A comprehensive parametric study reveals that the infiltration time depends on the nanopore rate and size, and a power-law scaling can be established, which reveals distinct quasi-equilibrium and kinetically limited regimes. The effective infiltration ratio, which reflects the completeness of the infiltration, negatively depends on the infiltration rate and the size of the nanopore. With loading rates close to the quasi-static regime, infiltration allows rearrangement of intermolecular structure and hydrogen-bond networks, whereas at high loading rates the process becomes kinetically constrained, resulting in delayed or partial infiltration. These understandings were explained through a detailed analysis of the structural and dynamic properties of the confined water molecules. Cylindrical radial density profile and the potential of mean force contours reveal that a larger loading rate suppresses configurational diversity, indicating a transition from dynamically relaxed to nonequilibrium constrained regimes. This study offers molecular-level insights into liquid infiltration subjected to various loading rates, which is critical to the design and development of nanofluidics-based anti-impact materials and systems.