Phase-Variant Lubricant-Infused Surfaces with Thermoresponsive Wettability Switching

Lubricant-infused surfaces (LISs) have recently emerged as highly effective solutions for reducing droplet pinning and enhancing droplet mobility. However, the lubricants commonly used in LISs are typically phase-invariant, remaining in the liquid phase across typical condensation working temperatures. In this work, we develop a phase-variant lubricant-infused surface (PV-LIS) by incorporating environmentally friendly, food-grade cold-pressed coconut oil as a lubricant. Surface characterization of this PV-LIS revealed a morphological transitions induced switchable wettability, enabling the surface to transition from hydrophilic in the solid phase to near-hydrophobic in the liquid phase of the infused coconut oil. This dynamic wettability further enables switchable condensation modes, where vapor condensation on PV-LIS transitions from filmwise in the solid phase to dropwise in the liquid phase. This temperature-dependent switch in condensation driven by the surface’s inherent wettability switching, makes PV-LIS beneficial for atmospheric vapor condensation, ambient-centric thermal management devices, and thermoresponsive droplet manipulation in microfluidic devices.