Polybutylene succinate/fractionated nano lignin@Ag composite films with tunable functions for active food packaging.

The development of eco-friendly and multifunctional food packaging materials is a major focus of contemporary research. This study presents tunable polybutylene succinate/fractionated nano lignin@Ag (PBS/NLs@Ag) composite films for active food packaging. The structural differences in fractionated lignin allowed functional tuning of the derived nanomaterials, leading to distinct performance advantages in the composite films. Low molecular-weight lignin-derived NLs@Ag endowed the composite with superior antibacterial efficacy (97.5 % inhibition of E. coli, 96.2 % inhibition of S. aureus) and antioxidant activity (DPPH clearance rate 49.8 %). Conversely, high molecular-weight lignin-derived NLs@Ag imparted exceptional photothermal conversion performance (reaching 70.4 °C under 0.9 W/cm2 NIR irradiation), enabling on-demand photothermal sterilization. Through reasonable design, these composite films extended shelf-life of grapes by 100 % via dual-mode antibacterial action. Furthermore, silver migration of all composites was below 0.9 mg/dm2, and cell viability exceeded 90 %, confirming biological safety. This work provides design strategies for customizable, high-performance packaging aligned with sustainability goals.