Fabrication of UV-resistant and superhydrophobic surface on cotton fabric by functionalized polyethyleneimine/SiO₂ via layer-by-layer assembly and dip-coating

In this research, a water-soluble ultraviolet (UV) absorber (PEI-H) was synthesized by grafting polyethyleneimine (PEI) with 2,4-dihydroxybenzophenone (UV-0). UV-resistant and superhydrophobic coating was fabricated upon cotton fabric by sequentially depositing PEI-H, silica sol (SiO₂) and hexadecyltrimethoxysilane via layer-by-layer assembly and dip-coating. The surface morphology, chemical composition, water-repellence, UV resistance property, durability against washing and abrasion test, air permeability as well as safety of the obtained fabric were investigated. It found that the obtained cotton fabric exhibited superior UV-resistant property with UPF value more than 800 which was attributed to the synergistic effect between organic UV absorber (UV-0) and inorganic UV shielding agent (SiO₂). Meanwhile, it also possessed superhydrophobicity, self-cleaning and anti-fouling properties with water contact angle of 154°. In addition, the multifunctional fabric after 20 washing times or 300 abrasion times remained excellent hydrophobicity and the corresponding UPF values were still 400+, showing an outstanding durability. Importantly, the obtained fabric was absolutely safe for human body.