Topography-Free Dual-Lubricant Patterned Slippery Surfaces for Programmable Droplet Control and High-Performance Water Harvesting

Abstract

Passive droplet control is critical for next-generation water harvesting, fluidic logic, and adaptive wetting surfaces. Here, we report a scalable, topography-free slippery liquid-infused porous surface (SLIPS) based on poly[1-phenyl-2-[p-(trimethylsilyl)phenyl]acetylene] (PTMSDPA). By selectively chemically fluorinating specific regions of the porous PTMSDPA film, followed by sequential infusion of two immiscible hydrophobic lubricants into their respective affinity-matched polymer matrices, this approach enables interfacial energy contrasts that direct droplet motion. The heterogeneous oil-infused porous surface (HOIPS) has a unique intrinsic fluorescence enabling real-time, dye-free visualization of infiltrated lubricant domains. Owing to its ultrathin (similar to 200 nm) and flexible polymer structure, the HOIPS enables controllable droplet motion on flat, flexible, and curved substrates without reliance on surface topography, physical confinement, or asymmetric geometries. Sub-millimeter-scale HOIPS line patterns enable controlled droplet coalescence, shedding diameter, and release timing during condensation, and optimized patterns exhibit up to 2.5x higher water-harvesting performance compared to fluorinated-oil-based SLIPS, providing a material-efficient strategy for liquid-repellent surfaces. Taken together, these results establish PTMSDPA-based HOIPS as a versatile platform for controlled droplet manipulation and condensation management.