Tuning Water Transport in Subnanometer-Sized Artificial Water Channels

Water transport through nanochannels is not only essential for biological functions but also holds promise for the development of advanced flow sensors and membranes. In this study, a series of artificial water channels with subnanometer-sized pores and tunable hydrophilicity were designed by mimicking the architecture of natural water channels. Experimental measurements and molecular dynamics (MD) simulations reveal that water transport can be modulated by pore hydrophilicity and electric field. Increasing pore hydrophilicity is associated with enhanced water permeability, consistent with continuous wetting and more uniform dipole alignment within the single-file water wires. In contrast, a hydrophobic backbone impedes water transport due to dewetting effects and broader dipole orientation distributions. In addition, a static electric field significantly facilitates water transport and leads to a membrane polarization-dependent water transport behavior by promoting more ordered water dipole configurations. These findings provide molecular-level and external-field-based strategies to regulate water transport in subnanometer channels and may guide the design of energy-efficient desalination membranes.