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-cleaningand anti-icing infrastructure areas under harsh service environmentssuch as very low temperature, strong wind, and sand impact. In thepresent study, an environment-friendly and self-adhesive superhydrophobicpolydopamine coating inspired by mussels had been successfully developedand its growth process was accurately regulated by formula and reactionratio optimization. The preparation characteristic and reaction mechanism,surface wetting behavior, multi-angle mechanical stability, anti-icing,and self-cleaning tests were systematically investigated. The resultsshowed that the superhydrophobic coating achieved an ideal staticcontact angle of 162.7 degrees and a roll-off angle of 5.5 degrees throughthe proposed self-assembly technique in an ethanol-water solvent.This was due to the coupling effect of constructing a hierarchicalroughness structure on the coating surface and reducing its surfaceenergy, which had been well documented by the surface morphology characteristicand chemical structure analysis. The as-prepared coating'sself-mechanical performances (tensile strength/shear holding power)and surface wear resistance (sand impact/sandpaper abrasion) behaviorswere tested, and results showed tight internal compactness and excellentmechanical robustness, respectively. Furthermore, the 180 degrees tape-peelingon 100 cycles and pull-off adhesion tests indicated that the abovecoating had significant mechanical stability and an increased percentage(57.4%) of interface bonding strength (27.4 MPa) with steel substratecompared to pure epoxy/steel. This was attributed to the metal chelatingcapacity between polydopamine catechol moieties and steel. Finally,the superhydrophobic coating had obvious self-cleaning propertiesby using graphite powder as a contaminant. Additionally, the coatinghad a higher supercool pressure and displayed much-reduced icing temperature,a longer icing delay time, and an extremely low and stable ice adhesionstrength (0.115 MPa) owing to the extreme water-repellence and mechanicaldurability.