Green Synthesis of Mechanical Robust Superhydrophobic CNT@PU Coatings with High Flexibility for Extensive Applications

Superhydrophobic coatings with high flexibility and mechanical durability can well address many practical application problems. To this end, we proposed and fabricated a kind of bio-based superhydrophobic (multi-walled carbon nanotubes) CNT@PU (polyurethane) coatings. It was demonstrated that the CNT@PU coatings with 64% soft segment content possessed the preferable bonding strength (5B) with metal substrates. The multi-walled carbon nanotubes, as additive materials, were used to construct the microscopic structures of the coating surfaces, which made polyurethane surface superhydrophobic (water contact angle being 156.9°, and water sliding angle being 4.3°). Furthermore, the high bonding strength between CNT and coating matrix led to robust mechanical durability of superhydrophobic CNT@PU coatings, and the coatings remained superhydrophobicity after 10 cycles of abrasion under 100 g load pressure. Also, the superhydrophobic coatings could well resist 5 cycles of tape-peeling action, and presented outstanding flexibility. The superhydrophobic CNT@PU coatings with high flexibility and mechanical durability could be applied to various substrates suggesting their big potential in future real-world application.