Photothermal responsive slippery surfaces based on laser-structured graphene@PVDF composites.

Photothermal responsive slippery surfaces with switchable superwettability are promising in the fields of biomedicine, self-cleaning, anti-corrosion, and lab-on-a-chip systems. However, the development of a light switchable slippery surface that combines high-performance photothermal materials with hierarchical microstructures of special orientation remains challenging, which limits the applications in anisotropic droplet manipulation. Herein, we demonstrate a photothermal responsive slippery surface based on laser-structured graphene and polyvinylidene difluoride composites (L-G@PVDF) for controllable droplet manipulation. The L-G@PVDF film exhibits high light absorption (∼95.4%) in the visible and NIR region. After lubricating with paraffin, the resultant surface shows excellent self-healing ability and light-responsive wettability change due to the photothermal effect of L-G@PVDF and the hot melting effect of paraffin. Additionally, by introducing anisotropic grooved structures, the paraffin-infused L-G@PVDF surface displays anisotropic wettability that further affects droplet manipulation under light irradiation. Also, the photothermal responsive slippery property endows the paraffin-infused L-G@PVDF surface with excellent anti-frosting and de-icing capability. Moreover, the smart paraffin-infused L-G@PVDF surface can be combined with a microfluidics chip for light-driven automatic sampling. This study offers insight into the rational design of photothermal responsive slippery surfaces for controllable droplet manipulation.