Mussel-Inspired Modification of Honeycomb Structured Films for Superhydrophobic Surfaces with Tunable Water Adhesion

In this paper, we report novel superhydrophobic surfaces with tunable water adhesion by combining mussel-inspired surface chemistry and bioinspired multiscale surface structures. Highly ordered honeycomb porous films were prepared from a diblock copolymer polystyrene-block-poly(N,N-dimethylaminoethyl methacrylate) by the breath figure method. Removing the top surface layer of the honeycomb films leads to pincushion-like surfaces. The films were coated with polydopamine after completely prewetting by ethanol, followed by the reaction with 1H,1H,2H,2H-perfluorodecanethiol for fluorination. As a result of the surface modification, both the honeycomb and the pincushion-like surfaces are superhydrophobic with a water contact angle higher than 150 degrees. Interestingly, the former is highly adhesive, on which water droplets are pinned at any tilted angles, whereas the latter is relatively low adhesive. Calculations indicate that the honeycomb films are in the Cassie state, whereas the pincushion-like surfaces are in the metastable Cassie state. On the basis of these superhydrophobic surfaces with different adhesive properties, no-loss transportation of water droplets has been demonstrated.