How surface curvature shapes water nanodroplets in air

Liquid surface curvature profoundly influences physical, chemical, biological, and engineering processes by modulating surface mechanical and thermodynamic properties. Curved interfaces are more prevalent than ideal planar ones and exhibit distinct size-dependent behaviors, yet the molecular-level consequences for interfacial water have not been fully elucidated. Herein we systematically explore how surface curvature regulates the structure, dynamics, mechanics, and thermodynamics of water nanodroplets. We demonstrate that the interfacial width decreases logarithmically with decreasing droplet radius R, consistent with curvature-induced suppression of capillary waves. Instantaneous interfacial analysis uncovers enhanced orientational ordering of surface molecules under higher curvature. Such structural changes give rise to a radius-dependent surface tension:(R) is well described by the classical Tolman equation with positive Tolman length. We further demonstrate that short-time fluctuations at the water surface can reliably predict long-time dynamic propensities, thus providing a practical approach for estimating the long-time dynamics of interfacial liquids in theoretical and computational investigations. The findings on curvature-dependent variations in energetics, structure, dynamics, and forces hold significant implications for processes involving micro- and nano-scale water droplets across multiple scientific and technological fields.