Wettability-switchable surface controlled by near-infrared light for droplet manipulation

Surface wettability switching is of great importance in both theoretical studies and practical applications. The surface wettability switching of thermally responsive shape memory polymer (SMP) by altering temperature has been widely discussed. However, meeting diverse application requirements by selectively switching the local wettability of thermally responsive SMP surfaces remains a significant challenge. Here, we prepared a photocontrolled wettability-switchable SMP surface by doping graphene oxide into a thermally responsive SMP, utilizing a template method. By leveraging the excellent photothermal conversion properties of graphene oxide and the thermal-responsive shape memory properties of SMP, the surface can reversibly change the surface morphology through loading deformation and near-infrared light irradiation. This enables achieving reversible switching of wettability between a superhydrophobic low-adhesion state and a hydrophobic high-adhesion state. The flexibility of near-infrared light irradiation allows for localized wettability switching on the surface by varying the position of light irradiation. Furthermore, we demonstrate the application of this photocontrolled SMP surface for droplet capture and remote, contactless selective release. This showcases the versatility of this surface for various application needs and highlights its immense potential in droplet-based microreactions, bioassays, chemical synthesis, and other applications.