Preparation and properties of colored silk fibers for wigs based on biomass polyphenols

Polyphenols are a group of natural organic compounds from nature that have been widely used in many fields. Silk, known for its excellent hand and bright luster, is composed of a substance similar to human hair - proteins in large quantities. This study utilized biomass polyphenols, including tea polyphenols (TP), gallic acid (GA), tannin acid (TA), and dopamine hydrochloride (DA), to dye silk fibers for application in wigs. We developed a dyeing method to achieve this goal, successfully producing silk in various colors, including yellow, brown, black, grey, and orange. Among these, samples dyed with polyphenols using Fe²⁺ and Ti⁴⁺ mordants, as well as those dyed with a combination of TP and zinc oxide, retained more than 80 % of their color depth after 20 washes, demonstrating good wash fastness. Moreover, DA-Fe²⁺, GA-Fe²⁺, TP-Fe²⁺ and DA dyed samples achieved a light fastness rating of 5, indicating excellent resistance to sunlight. Additionally, the characteristics and morphology of the silk before and after dyeing were analyzed using various spectroscopic and analytical techniques. Adsorption tests showed that most polyphenol dyes followed the Freundlich isotherm. However, TP self-polymerization and DA/GA with Fe²⁺ mordant dyeing aligned with first-order kinetics, while others followed second-order kinetics. The dyed silk fibers exhibited good anti-UV performance and had no significant change in tensile strength. Furthermore, using DA-Fe²⁺ to dye the back hair of mice did not result in adverse effects. This method is eco-friendly, mild, and cost-effective, making it highly promising for applications in the wig industry.