Tunable Lotus Leaf\nEffect by Three-Dimensionally Printed\nStretchable Objects

Adjustable wettability is important for various fields,\nsuch as\ndroplet manipulation and controlled surface adhesion. Herein, we present\nhigh-resolution 3D stretchable structures with tunable superhydrophobicity,\nfabricated by a stereolithography-based printing process. The printing\ncompositions comprise nonfluorinated monomers based on silicone urethane\nwith dispersed hydrophobic silica particles. 3D lotus-like structures\nwere designed and printed, having microsize pillars located at the\nexternal surfaces, with controlled dimensions and interspacing. The\ndesign of the pillars and the presence of the hydrophobic silica particles\nresulted in superhydrophobicity due to the surface structuring and\nentrapment of air between the pillars. The best structures display\na contact angle of 153.3° ± 1.3° and rolling angle\nof 3.3° ± 0.5°, and their self-cleaning, water repellency,\nand buoyancy are demonstrated. The durability of the structure over\ntime, water immersion, and heat exposure were tested, confirming the\npreservation of superhydrophobicity under these conditions. Upon stretching\nthe surfaces, the interpillar distances change, thus enabling tuning\nthe wetting properties and achieving good control over the contact\nand rolling angles, while the stretching-induced superhydrophobicity\nis reversible. This approach can expand the potential applications\nof superhydrophobic soft materials to fields requiring control over\nthe wetting properties, including soft robotics, biomedical devices,\nand stretchable electronics.