Nondestructive removal of superhydrophobic coatings by an electric switch.

Extensive efforts have been made to enhance the durability of superhydrophobic coatings by adhesives, yet it raises a challenge to nondestructively remove the failed coatings. Here, we propose a nondestructively removable superhydrophobic (NRS) coating by an electrical switch, inspired by the nondestructive ecdysis of snakes. To achieve this, we sequentially spray i-layer and e-layer using electro-responsively epoxy-based ionic adhesive and superhydrophobic CNT coating, respectively. Its adhesion energy to stainless steel sheets significantly declines from 2.46 kJ m-2 to 0.01 kJ m-2 (about 99.6% of removal efficiency), through the disordered-ordered switching of free ions, only applying 90 V DC voltage for 3 min. This enables it to be nondestructively removed from the substrates even after 10 recoating cycles. This work offers a common strategy to sustainably protect the metal substrates and facilitates their recycling, showing great potential in green manufacturing and surface protection for large-scale equipment.