Polydopamine-induced growth of mineralized γ-FeOOH nanorods for construction of silk fabric with excellent superhydrophobicity, flame retardancy and UV resistance

Due to the increasing pollution produced by the textile industry, environmentally friendly methods are becoming extremely important. In this work, silk fabrics (SFs) were modified with a series of natural polyphenols under the catalysis of laccase and then reacted with a ferrous solution to construct fabric surfaces with a micro-nano structure. Among the modified SFs, dopamine-Fe-modified silk fabric (PDA-Fe-SF) had an outstanding hydrophobicity and was screened as a research model. The preparation process was simple and eco-friendly, as it did not use toxic organic solvents, fluorine-containing substances, or halogen-containing and phosphorus-containing flame retardants. The structure and properties of the modified silk fabrics were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), a vertical combustion test and so on. The results showed the surface of the PDA-Fe-SF was coated with dense and uniform needle-like γ-FeOOH nanorods and had a high contact angle (CA) of up to 165° and good self-cleaning performance. The damaged carbon length of the burned fabric was only 10.5 cm in the vertical combustion test, and the UPF value of the PDA-Fe-SF can reach 72, which classifies this material in the Excellent UV protection level. The modified silk fabrics had good mechanical properties and durability. Through the electrostatic potential analyses of polyphenols and their oligomers, the FeOOH formation mechanism of the surface morphology could reveal that the differences in the polymerization types, structures and water solubilities of the polyphenol polymers would affect the way in which the polymers deposit and the amount of deposition that occurs, and the number of coordination sites for Fe2+ and the resulting various surface morphologies on the silk fabric could be determined.