Atomic Layer Deposition of Al₂O₃/TiO₂ Multilayer Films on Silk for High-Efficiency UV Shielding Properties

Silk fiber, as a luxurious textile raw material, is widely used in the textile industry due to its excellent mechanical properties and wearing comfort. However, the poor (ultraviolet, UV) light stability of silk affects its further application in high-end textiles, fashionable apparel, and smart materials. Although surface modification can endow the excellent UV resistance of silk fibers, it often reduces its comfort property. Herein, a laminated ultrathin Al₂O₃/TiO₂ coating with a total thickness of 120 nm is fabricated on the surface of silk fiber via a modified atomic layer deposition (ALD) technique. The tenacity of ALD-coated silk can maintain 61.1% of its original value after exposure to intense UV light (640 mW/cm²) under high temperature (>200 °C) for 6 h, which is far superior to other work that has been reported. This can be attributed to the synergistic effect of the reflection of UV light by the multilayer film barrier, the strong oxidizing free radicals by the Al₂O₃ layer in the innermost layer, and thermal shield of laminated ultrathin Al₂O₃/TiO₂ film. ALD-coated silk fabrics can also demonstrate a multicycle laundering durability, thermal and chemical stabilities, and flame retardancy. More importantly, the wearing comfort of the modified silk has no obvious change. This method provides principle and technical guidance in high-performance and multifunctional fibers and devices.