Tunable Lotus Leaf Effect by 3D-printed stretchable objects

Adjustable wettability is important for various fields, such as droplets manipulation and controlled surface adhesion. Herein, we present 3D stretchable structures with tunable superhydrophobicity fabricated by stereolithography-based printing at high resolution. The printing formulations comprise commonly available, non-fluorinated monomers with dispersed hydrophobic silica particles. 3D Lotus-like structures were printed, having micro-size pillars located at the external surfaces, with controlled dimensions and inter-spacings. The pillars design and the presence of the hydrophobic silica particles resulted in superhydrophobicity due to the surface structuring and entrapment of air in between the pillars. The best structures display a contact angle of 153.3°±1.3°and a rolling angle of 3.3°±0.5°, and their self-cleaning, water repellency, and buoyancy are demonstrated. Upon stretching the surfaces, the inter-pillar distances change, thus enabling tuning the wetting properties and achieving good control over the contact and rolling angles, while the stretching-induced superhydrophobicity is reversible. This approach can expand the potential applications of superhydrophobicity of soft materials to fields requiring control over the wetting properties, including soft robotics, biomedical devices, and stretchable electronics.