Surface hydrophobization of cotton via laccase‐mediated polydopamine deposition and dodecyl gallate grafting

Abstract

Natural fibers containing components with phenolic hydroxyl groups, such as jute, wool, and silk, can be directly modified by laccase‐catalyzed grafting. However, cellulosic fibers like cotton cannot be functionalized in this manner. In this work, we developed a facile two‐step method to graft polymers on cotton fabric via laccase catalysis. First, polydopamine (PDA) coating was deposited on the surface of the cotton fabrics via catalysis of laccase/2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) system. Then, the newly formed PDA coating acted as the secondary reaction platform for subsequent laccase‐mediated grafting of hydrophobic monomer dodecyl gallate (DG). The oxidation of dopamine (DA) catalyzed with the laccase/TEMPO system was investigated using UV–visible (UV–vis) spectroscopy. The scanning electron microscopy (SEM) and X‐ray photoelectron spectroscopy (XPS) results verified that the PDA was coated on the surface of cotton fibers. Fourier transform infrared (FTIR) spectra indicated that the PDA‐coated cotton was successfully grafted with DG (DG‐PDA‐cotton). According to the weighting method, the grafting percentage was about 1.06%. The hydrophobicity of the DG‐PDA‐cotton fabrics was greatly improved with a contact angle of 133°. Also, the grafted cotton fabrics show repellency of water‐soluble stains like coffee, milk, and tea. This study provides a new strategy for surface modification of cotton by laccase‐mediated grafting, which offers the references for the green fabrication of cotton fabrics with improved functionalization.