Decoupling droplet transport from the nucleation interface via wire-guided sliding condensation

In classical dropwise condensation, droplet transport is restricted by substrate-controlled pinning forces, which enforce a growth-to-detachment pathway. We hypothesize that externally guided sliding interfaces can decouple droplet motion from the nucleation surface and create a new interfacial dynamic regime governed by wettability-directed energy release rather than size-limited detachment.

To test this hypothesis, we fabricated Ti/TiO₂/PTFE hydrophobic tubes and wrapped them with superhydrophilic or hydrophobic stainless-steel wires to form heterogeneous sliding interfaces. High-speed imaging, droplet statistical analysis, and heat-flux measurements (ΔT_lmtd = 8-76 K) were combined with purely two-dimensional phase-field simulations (without vapor condensation) to resolve film-wise wicking, coalescence-driven acceleration, and contact-line depinning along wire-guided pathways.

The sliding interfaces create a distinct interfacial state where droplet motion is dominated by wetting asymmetry and surface-energy conversion. This mechanism enables early-stage detachment that does not depend on classical critical-size constraints. Hydrophobic sliding channels provide strong decoupling, ensure continuous surface renewal, and achieve a 38.1% enhancement in heat flux, reaching 749 kW m^-2 at ΔT_lmtd ≈ 76 K. This study introduces an externally guided and structurally decoupled droplet transport mechanism that broadens the fundamental understanding of capillarity-driven dynamics and supports scalable, high-performance condensation interfaces.