Designing robust, antimicrobial and UV-shielding poly(lactic acid) nanocomposites by multi-functional nanochitin via surface chemistry: Preparation and food packaging application

The development of mechanically robust, antimicrobial, and UV-shielding poly(lactic acid) (PLA) film is highly desired as food packaging materials. Herein, aldehyde-functionalized chitin nanocrystals (ChNCs-PVMA) with immobilized AgNPs (Ag@ChNCs-PVMA), were prepared and applied as multi-functional biomass-based nanofillers for PLA. The surface-grafted poly(vanillin methacrylate) (PVMA) chains not only effectively improve the interfacial interaction between the nanocrystal and PLA, but also act as reductant and stabilizer for the in situ synthesis of AgNPs by the abundant aldehyde groups. The incorporation of Ag@ChNCs-PVMA nanofillers into PLA matrix displays reinforcing, antimicrobial, and UV-shielding functions. The PLA/Ag@ChNCs-PVMA-5 film achieves complete absorption of UVC (200-275 nm) and UVB (275-320 nm), and ∼90% absorption at the region of UVA (320-400 nm), while maintaining good transparency. Furthermore, the PLA/Ag@ChNCs-PVMA-5 film exhibit excellent antimicrobial activity against E. coli and S. aureus . These interesting results support the composite films to be applied in food packaging, demonstrating prolonged preservation time of strawberries.