Grafting of Poly(tyrosine) by Laccase Improves the Tensile Strength and Anti-shrinkage of Wool

The laccase-assisted grafting of poly(tyrosine) is performed aiming to impart shrink-resistant properties to the wool materials. Laccase is able to catalyze the oxidation of tyrosine into dityrosine efficiently. When the reaction is performed using poly(ethylene glycol) (PEG) as the template, the tyrosine oxidation gives rise to differentiated oxidation products, including di-, tri-, and tetra-tyrosine, promoting a higher grafting onto the wool fibers. The characterization of the grafted wool fibers and fabrics reveals some loss of crystallinity (about 4% of crystallization index) and thermal resistance (decreasing from 232°C to 224°C) resulting from the grafting process. However, the new bonds established between the new oxidation products and the amino groups of the wool promote an improvement, not only of the shrinkage properties (1.87% of area shrinkage) but also of their mechanical behavior (increasing by 45.28%). The strategy herein presented demonstrates the potentiality to be applied as a “green” process for wool anti-shrinkage without compromising the fibers’ performance.