In Situ Coloring and Antibacterial Finishing of Silk Fabrics Through Fenton-Induced Deposition of Caffeic Acid and Silver Nanoparticles

Due to the weak interaction between dye molecule and silk fiber, traditional acid dyeing of silk fabrics has some shortcomings such as high energy consumption and poor dyeing fastness. In the present work, in situ coloring of silk fabric was carried out via graft polymerization of caffeic acid (CA) by using a Fenton system consisting of FeCl 2 and H 2 O 2 . Subsequently, silver ions were reduced to silver nanoparticles (AgNPs) by poly(caffeic acid) (PCA) grafted in silk fibroin and deposited on the fiber surfaces, aiming at improving the antibacterial property of silk fabric. The results indicate that it is feasible to achieve in situ dyeing of silk fabrics under low temperature condition through graft polymerization of CA, and the color depth (K/S value) increases to 4.8. Meanwhile, the iron ions might further form coordination bonds with PCA and tyrosine residues in silk fibers, which can improve the washable resistance and wet rubbing fastness of the dyed fabrics, reaching the grade of 4–5. In addition, PAC grafted on silk fibers exhibits high reductivity, which can reduce silver ions and guide the AgNP deposition on the surface of silk fibers. This allows silk fabrics to achieve efficient and durable antibacterial effects, and the antibacterial rate remains above 98% even after cyclic washings. The present work provides a novel approach for in situ coloring and functionalization of silk fabrics without additional synthetic dyes or antibacterial agents.