Cardanol-induced surface rearrangement of fluorine in polyurethane acrylic coatings to achieve self-cleaning and anti-graffiti properties

In this paper, a UV-curable solvent-free biomass polyurethane acrylic material was prepared by a two-step method, including the synthesis of cardanol-based polymerizable monomer and cardanol-based resins. This resin could form excellent self-cleaning and anti-fingerprint coatings after suffering from UV curing. It was found that the cardanol alkyl chain broke the hydrogen-fluorine (H⋅⋅⋅F) bond between the F atom of perfluoroalkyl acrylate and H-N of polyurethane in the coating. And cardanol alkyl chain synergistically induced the directional arrangement of F atoms to the surface, which improved the hydrophobic properties of the coating. This coating has good resistance to common pollutants such as water, ethanol, milk, coffee, dust, and fingerprints, and is suitable for various substrates such as sheet iron, and PET sheet. Due to the high degree of crosslinking in the coating, it can effectively prevent the penetration of acidic and alkaline substances, maintaining good self-cleaning performance even after immersion in a solution of strong acids or alkalis (pH 1–13) for 72 h. The use of cardanol-induced coating fluorine atom surface rearrangement technology can significantly reduce the amount of fluorine and also provide new ideas for the design of self-cleaning and anti-graffiti materials.