The Synergistic Effect and Mechanism of CNF/TiO ₂ /Tannic Acid Self-Assembly in Enhancing the Anti-Ultraviolet Property of Silk Fabrics

Silk fabrics were treated with self-assembly system of titanium dioxide (TiO[Formula: see text], nanocellulose (CNF) and tannic acid for UV protection. The anti-UV finishing agent and finishing solution were characterized and analyzed by ultraviolet (UV) absorption spectroscopy, and the UV absorption properties of TiO 2 , CNF and tannic acid were investigated. The results revealed differences in the T(UVA) and T(UVB) parameters among the three anti-UV finishing agents. Scanning electron microscopy (SEM) was used to observe the morphology of freeze-dried samples of the anti-UV finishing agent dispersion and its composite finishing solution. It was found that the anti-UV finishing agent dispersion and its self-assembly system were porous three-dimensional microstructure after freeze-drying. The UV transmittance and UPF value of the finished silk fabric were tested. The UV transmittance of the finished silk fabric was significantly reduced and the UPF value was significantly increased. Although the UPF value of the finished silk fabric remained above 50 after 50 times of washing, the reason is that tannic acid can react with lysine or arginine residues of silk protein to form a covalent cross-linking network, which can improve the washing resistance of self-assembly system on the surface of silk fabric. In addition, according to the detection of anti-UV performance of silk fabric by UV sensor card, only weak UV rays pass through the finished silk fabric, causing relatively little harm to human body. In conclusion, the nano-scale multilayer structure formed by the self-assembly of CNF/TiO 2 /tannic acid significantly enhanced the UV shielding efficiency of silk fabrics.