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 (–), we discover that wettability influences condensation kinetics: reducing contact angles from to 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 () 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.