Superamphiphobic coatings with antifouling and nonflammable properties using functionalized hydroxyapatite

Abstract

Functional superamphiphobic coatings have attracted much attention due to their promising application prospects in oil transportation and anti-contamination, which call for the requirements of flame retardancy. Herein, a novel superamphiphobic F–HAP–SiO₂ hybrid coating with excellent flame retardant properties was fabricated by in situ growing SiO₂ particles on hydroxyapatite. For the prepared superamphiphobic hydroxyapatite (Ca₁₀(OH)₂(PO₄)₆) coating, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, energy dispersive spectroscopy (EDS), thermogravimetric analysis and three-dimensional topography were performed. The superamphiphobic hydroxyapatite (Ca₁₀(OH)₂(PO₄)₆) coating features high contact angles and low sliding angles for various liquids, including n-decane with low surface tension (23.3 mN m⁻¹). Different liquid droplets can retain a perfectly quasispherical shape on the coating surface. Most interestingly, liquid marbles wrapped up by this superamphiphobic powder can “stand” on various substrates without any collapse. Moreover, it is noted that the intrinsic fire-resistant nature of the coating enables its application onto various substrates and reduces the risk of fire due to the excellent oleophobic and oil resistant properties of the coating, exhibiting its great substrate independence. In addition, the coating shows a good repellency for liquids (HCl, NaOH, milk, honey, and coffee) after the mechanical damage tests. In summary, the fluorinated hydroxyapatite (Ca₁₀(OH)₂(PO₄)₆) coatings with superior superamphiphobicity, flame-retardancy, substrate independence nature and mechanical stability show promising potential in water/oil/fire-proof, self-cleaning, and antifouling coating applications.