Lipase-Assisted Covalent Bioincorporation of Chitosan Nanoparticles on the Surface of Polyester Fabric

Poly(ethylene terephthalate) (PES) is a commonly used synthetic fiber due to its excellent physical properties, resistance, and low cost. However, some undesirable characteristics, including hydrophobicity and flammability, limit its broader application. Surface modification is an efficient way to enhance or introduce new technological properties to textiles. Biocatalysis processes, particularly those using lipases, can be employed to hydrolyze ester groups on PES’ surface, generating COOH and OH groups. These reactive groups enable the uncommon covalent incorporation of nucleophilic nanoparticles. Chitosan nanoparticles (CNPs) are promising candidates for combination with PES, as they are biocompatible and biodegradable and can impart new properties, including UV protection and flame-retardant properties. In this work, the surface hydrolysis of PES using 18 commercial lipases was investigated, along with an optimization that varied pH, time, temperature, and enzyme amount. The subsequent covalent bonding of CNPs to the fiber was studied using various strategies. PES hydrolysis was efficiently achieved with lipase A from Aspergillus niger under mild conditions (30 mg enzyme, pH 7, 40 °C, 90 min), confirmed by titration and dyeing assays. The covalent incorporation was feasible, and the best methodology applied ultraviolet (UV) exposure for a 4 h reaction. The modified PES retained its dyeability for dispersing dyes and demonstrated improved performance with an acid dye (Orange Triacet RN), making it a more environmentally friendly option. Additionally, the treatment provided flame-retardant and anti-drip properties, as well as increased UV blocking.