Reversible Control between Sliding and Pinning on Femtosecond Laser-Treated Nickel Foam Slippery Surfaces

Bioinspired slippery surfaces with excellent abilities, such as antifouling, anticorrosion, and drag reduction, have gained increasing attention due to their multifunction in chemistry, biology, and medicine. However, the present thermally responsive methods used for in situ paraffin-infused slippery surfaces (PISS) are usually based on a surface heat source or certain specific photothermal materials, which seriously hinders their practical applications. Herein, we present a kind of in situ PISS processed by femtosecond laser on nickel (Ni) foam with reversible droplet behavior between sliding and pinning controlled by a point heat source. By alternately loading and unloading the point heat source, switchable wettability for liquid droplets can be achieved. The reaction time of this smart surface to the temperature change is 4.47 +/- 1.14 s. The relationship between droplet volumes and inclined angles on four different surfaces is quantitatively investigated. Furthermore, the as-prepared PISS display an impressive self-healing ability. In addition, by flexibly changing the action path of the point heat source, the droplet can realize the movement of different curves. This functional surface and in situ control method will be a promising candidate for manipulating droplet directional sliding behavior and smart temperature-responsive surfaces.