Rational design of polymer film morphology via structure-performance linkage for enhanced condensation performance.

Dropwise condensation is essential for heat transfer in power generation, thermal management, and water harvesting, yet remains limited by surface modifications that often fail to maximize the advantages of dropwise mode. Here, we develop a morphology-based design strategy using conformal, pinhole-free fluoropolymer films deposited by initiated chemical vapor deposition. By controlling film thickness and thermal annealing, we identify a structure-performance relationship linking nanoscale aggregate morphology, wettability, and condensation dynamics. Thin films (≤ 100 nm) contain smaller, more densely distributed aggregates and lower roughness than 500 nm films, resulting in higher nucleation densities. Thermal annealing increases crystalline ordering while reducing contact angle hysteresis, enabling droplet removal at smaller diameters. These coupled effects increase surface renewal by combining rapid droplet nucleation with frequent sweeping. Under pure-vapor conditions, the morphology-controlled films improve heat transfer by ~50% compared with hydrophobic self-assembled monolayers, providing design principles for polymer coatings in condensation-based thermal systems.