Preparation of lignin-silver nanoparticles in deep eutectic solvent systems for multifunctional polyvinyl alcohol composite films

Currently, packaging films made from polyvinyl alcohol (PVA) often suffer from issues such as poor water resistance, weak mechanical properties, and limited functionality. Herein, lignin, a renewable and abundant biomass constituent, was utilized as a dual-role agent, serving as both reductant and stabilizer, to synthesize core-shell lignin‑silver nanoparticles (AgLNPs) within deep eutectic solvent (DES) systems. The influence of various DES formulations on the physicochemical properties of AgLNPs was systematically studied, leading to the selection of particles exhibiting enhanced compatibility with PVA for composite films fabrication. Results indicate that alkaline DES systems enable the synthesis of AgLNPs with smaller particle sizes and improved uniformity. The mechanical properties and hydrophobicity of the PVA composite films are significantly enhanced due to the unique catechol groups and the distinctive micro-nano rough surface formed during film formation. Notably, the composite exhibited a tensile strength of 37.9 MPa, an increased static water contact angle of 104.2 o , alongside enhanced thermal stability, UV-blocking capacity, and antimicrobial efficacy. This approach offers a promising avenue for advancing PVA film performance and valorizing lignin in sustainable materials engineering.