Light-Driven Actuator Using Superhydrophobic Polymer Composite Films for Biomimetics and Water-Droplet Manipulation.

Combining light-stimulated actuators with large deformation and high sensitivity with superhydrophobic surfaces has great applications in emerging fields, such as smart bionics, microfluidic devices, and droplet manipulation. Here, using self-assembly and spray methods, light-responsive superhydrophobic films driven by UV light were prepared. Due to the low surface energy of polydimethylsiloxane (PDMS) and micronanostructures of ZnO, the film surface exhibited excellent superhydrophobicity. With the incorporation of light-responsive azobenzene groups, the film achieved a transition of azobenzene molecules from linear trans structures to bent cis structures under UV light irradiation. This change endowed the film with excellent driving properties, allowing the film to achieve bending angles of up to 90° under UV light irradiation with a power density of 70 mW/cm. Additionally, the prepared light-responsive superhydrophobic films remained stable in bending tests, high temperatures, UV irradiation, and various organic solvent immersion tests. Based on the outstanding superhydrophobic and light-driven properties, light-responsive superhydrophobic films can be designed for applications in the fields of biomimetics and droplet manipulation.