Light-Switching Surface Wettability of Chiral Liquid Crystal Networks by Dynamic Change in Nanoscale Topography.

Nano- and microscale morphology endows surfaces that play conspicuous roles in natural or artificial objects with unique functions. Surfaces with dynamic regulating features capable of switching the structures, patterns, and even dimensions of their surface profiles can control friction and wettability, thus having potential applications in antibacterial, haptics, and fluid dynamics. Here, a freestanding film with light-switchable surface based on cholesteric liquid crystal networks is presented to translate 2D flat plane into a 3D nanometer-scale topography. The wettability of the interface can be controlled by hiding or revealing the geometrical features of the surfaces with light. This reversible dynamic actuation is obtained through the order parameter change of the periodic cholesteric organization under a photoalignment procedure and lithography-free mode. Complex tailored structures can be used to encrypt tactile information and improve wettability by predesigning the orientation distribution of liquid crystal director. This rapid switching nanoprecision smart surface provides a novel platform for artificial skin, optics, and functional coatings.