Highly compressible and stretchable superhydrophobic coating inspired by bio-adhesion of marine mussels

Mechanical durability is an important concern for the fabrication and application of superhydrophobic coatings but rare studies have reported that such a coating could withstand both large-strain compression and stretching. In this study, a highly compressible and stretchable superhydrophobic coating was constructed on the surface of commercial polyurethane (PU) sponges, inspired by the bio-adhesion of marine mussels. The coating consisted of sandwich-like multilayers constructed through layer-by-layer deposition of polydopamine (PDA) films and Ag nanoparticles. Under large strain conditions, the resulting coating could withstand 6000-cycle compressions, as well as 2000-cycle tensile measurements without losing its superhydrophobicity, exhibiting outstanding mechanical robustness among its existing counterparts. This high compressibility and stretchability is believed to arise from strong interactions between silver nanoparticles, PDA interlayers and sponge skeletons. In addition, the coating also exhibited excellent anti-icing property at -15 degrees C. Because of a simple synthesis process and almost nonselective adhesion of PDA, these results might provide a facile and versatile route for fabricating mechanically robust coatings on elastic substrates for various technological applications.