Evolution of the water cluster in pore condensation

Abstract

Pore condensation enables vapor-liquid transitions below saturation humidity, yet the microscopic dynamics of the embryo formation and cluster growth within the pore remain unresolved. Through molecular simulations on tunable-wettability surfaces (124°-90°), we discover that wettability influences condensation kinetics: reducing contact angles from 124° to 90° decreases the molecular displacement by ≈60% and the molecular potential energy by ≈10% for the condensed water molecules, increasing vapor capture tenfold. Pores enhance nucleation on hydrophobic surfaces (124°) by restricting molecular mobility, an effect attenuated with increasing wettability. Specifically, we identify four distinct cluster evolution modes: intra-pore (confined growth), on-plane, tumble (pore-to-pore migration), and bounce. Analysis of the above modes reveals that spatial confinement accelerates initial nucleation but suppresses later-stage coalescence. As a result, the cluster growth rate of the intra-pore mode can be initially higher than that of the flat reference but later drops below. This work establishes a microscopic mechanism for pore condensation.

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2026 The Author(s). Droplet published by Jilin University and John Wiley & Sons Australia, Ltd.