Construction of the Stable Lubricant Film on One-Dimensional Cone-Structured Surfaces for Directional Liquid Transport

Directional liquid transport along one-dimensional structures finds vast applications in fog harvest, liquid separation, sensing, chemical synthesis, and numerous other scenarios. Dynamically, the liquid transport speed is boosted by the driving force and retarded by the hysteresis from the liquid/substrate interface. A capillary force-relied lubricant film or a covalently attached polymer brush on the surface could increase liquid mobility temporarily by reducing the interfacial hysteresis. However, the easy depletion of the lubricant film and the stringent restriction of the substrate severely hamper droplet's directional transport in a long run. Herein, we report a feasible and durable hysteresis reduction design with the polymer-brush stabilized lubricating surface (PBSLS). The PBSLS is achieved through incorporating liquid-like polydimethylsiloxane brushes (b-PDMS) and the liquid PDMS oligomer (o-PDMS). The covalent attached b-PDMS "locks" the lubricant oil o-PDMS to the cone surface via strong intermolecular van der Waals force in between. The PBSLS on the cone surface can be sustained under constant shearing force from liquid transport for at least 6 h. A cone with such PBSLS shows increased ability of droplet transport and enhanced fog collection performance in the long run. This design supplies an effective way toward regulating macro-level interfacial performance through surface design on the molecular level.