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The suspension of nanoporous particles in a nonwetting liquid provides a unique solution to the crux of superfluid, sensing, and energy conversion, yet is challenged by the incomplete outflow of intruded liquid out of nanopores for the system reusability. We report that a continuous and spontaneous liquid outflow from hydrophobic nanopores with high and stable efficiency can be achieved by regulating the confinement of solid–liquid interactions with functionalized nanopores or/and liquids. Full-scale molecular-dynamics simulations reveal that the grafted silyl chains on nanopore wall surfaces will promote the hydrophobic confinement of liquid molecules and facilitate the molecular outflow; by contrast, the introduction of ions in the liquid weakens the hydrophobic confinement and congests the molecular outflow. Both one-step and multistep well-designed quasistatic compression experiments on a series of nanopores/nonwetting liquid material systems have been performed, and the results confirm the outflow mechanism in remarkable agreement with simulations. This study offers a fundamental understanding of the outflow of confined liquid from hydrophobic nanopores, potentially useful for devising emerging nanoporous-liquid functional systems with reliable and robust reusability.

 

Understanding the invasion of a liquid into porous structures is the foundation of the characterization of the porosity-related properties of materials and is also of fundamental importance in the design of porous solid–liquid enabled energy protection systems, yet whether solid pores deform has been unclear so far. Here, we present a competition mechanism between liquid infiltration and cell wall buckling deformation by investigating a liquid nanofoam (LN) system subjected to quasi-static compression. The critical buckling stress of the cell wall and the infiltration pressure of liquid invasion into nanopores are studied and correlated through numerical simulation and experimental validation to reveal the quantitative relationship between nanopore deformation and liquid invasion. The analysis shows that liquid infiltration occurs, independent of the axial buckling stress of the cell wall; in contrast, the nanopore collapses radially when the radial collapse pressure is lower than the pressure of liquid infiltration, preventing the liquid invasion. Comprehensive molecular dynamics (MD) simulations are performed and demonstrate the deformation behavior of nanopores and cell wall–liquid interactions in a broad range. Pressure-induced compression experiments on a silica-based LN system are carried out and validate these theoretical and MD results.