Soft elastic superhydrophobic cotton: A new material for contact time reduction in droplet bouncing

Reducing the contact time while water droplets impact on solid surface has become a vital object concerned by many researchers in recent years. However, previous methods of preparing superhydrophobic surfaces for shortening the contact time, with low efficiency and high expense, are not suitable for large-area fabrication and some obtained surfaces cannot work unless droplets just impact on the specific textures which limits their application in the field of anti-icing from freezing rain. Moreover, the contact time reduction has been mostly observed on metals, but rarely on nonmetals. Here, a facile method of fabricating superhydrophobic cotton was first conducted to largely reduce the contact time between droplet and substrate surface, which obviously eliminated the previous weakness. The treated cotton showed an excellent self-cleaning property and water droplet could also easily roll off the surface. The subsequent impact experiments show that the contact time was shortened by similar to 36% compared with that on the regular hard superhydrophobic surface. Moreover, the influence of the impact velocity and droplet radius on the overall contact time or spreading time and recoiling time had been also observed. And the elasticity of soft elastic superhydrophobic material plays a significant role in making the droplet early bounce off the surface causing a large contact time reduction, which leads to a new way to understand the dynamics of bouncing droplets.