Immobilizing quercetin to surface-activated PLA for durable golden yellow and ultraviolet protection using polyazidine crosslinker

Polylactic acid (PLA) is a promising biodegradable polymer, however conventional disperse dyeing departs it from eco-friendly conception; the limited compatibility with bio-based dyes also leads to the low durability of colour and functionality. This study presents an effective strategy for fabricating durably golden yellow and UV protective PLA integrating quercetin (Qc) and formaldehyde-free crosslinker (Trimethylolpropane tris-2-methyl-1-aziridinepropionate, TTMAP). Results show that a notable increase in the K/S of PLA from 5.83 to 14.97 takes place when the TTMAP concentration escalates from 0 to 5 g/L under the help of methyl cinnamate (MC) and deep eutectic solvent(DES). Under optimal condition, the fabricated PLA displays a shining golden appearance and UV shielding property, with colour fading rate of 6% and well maintained UPF50+ rating after five cycles of washing. The mechanism study reveals that the enhanced adhesion between Qc and PLA by TTMAP is a combining effect of chemical crosslinking and physical encapsulation. In all, the method developed in this research not only pushes forward the development of next generation bio-based PLA product approaching to the targets of sustainable textile industry and global carbon neutralization, but is also transferable to the surface modification of PLA material in other fields such as medical care, functional composite, packaging.