Mussel-Inspired Fabrication of an Environment-Friendly and Self-Adhesive Superhydrophobic Polydopamine Coating with Excellent Mechanical Durability, Anti-Icing and Self-Cleaning Performances

Superhydrophobic coatings play a crucial role in self-cleaning and anti-icing infrastructure areas under harsh service environments such as very low temperature, strong wind, and sand impact. In the present study, an environment-friendly and self-adhesive superhydrophobic polydopamine coating inspired by mussels had been successfully developed and its growth process was accurately regulated by formula and reaction ratio optimization. The preparation characteristic and reaction mechanism, surface wetting behavior, multi-angle mechanical stability, anti-icing, and self-cleaning tests were systematically investigated. The results showed that the superhydrophobic coating achieved an ideal static contact angle of 162.7° and a roll-off angle of 5.5° through the proposed self-assembly technique in an ethanol-water solvent. This was due to the coupling effect of constructing a hierarchical roughness structure on the coating surface and reducing its surface energy, which had been well documented by the surface morphology characteristic and chemical structure analysis. The as-prepared coating's self-mechanical performances (tensile strength/shear holding power) and surface wear resistance (sand impact/sandpaper abrasion) behaviors were tested, and results showed tight internal compactness and excellent mechanical robustness, respectively. Furthermore, the 180° tape-peeling on 100 cycles and pull-off adhesion tests indicated that the above coating had significant mechanical stability and an increased percentage (57.4%) of interface bonding strength (27.4 MPa) with steel substrate compared to pure epoxy/steel. This was attributed to the metal chelating capacity between polydopamine catechol moieties and steel. Finally, the superhydrophobic coating had obvious self-cleaning properties by using graphite powder as a contaminant. Additionally, the coating had a higher supercool pressure and displayed much-reduced icing temperature, a longer icing delay time, and an extremely low and stable ice adhesion strength (0.115 MPa) owing to the extreme water-repellence and mechanical durability.