Plasticized poly(lactic acid) reinforced with antioxidant covalent organic frameworks (COFs) as novel nanofillers designed for non-migrating active packaging applications

A 2D Covalent Organic Framework (named [HC≡C]0.5-TPB-DMTP-COF) was synthesized and post synthetically functionalized with dopamine via Copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction (COFDOPA) to obtain 2D nanoparticles with antioxidant activity. COFDOPA nanoparticles were exfoliated into nanosheets (COFDOPA-e) and incorporated into plasticized poly(lactic acid) (PLA) matrix with 15 wt% of acetyl trybutyl citrate (ATBC) to develop non-migratory sustainable packaging. The effect of COFDOPA and exfoliated COFDOPA-e (in 0.5, 1 and 3 wt%) on the structural, thermal and mechanical properties of PLA-ATBC was studied. The bionanocomposites loaded with low amounts of COFDOPA-e (0.5 wt% and 1 wt%) resulted optically transparent and showed good interfacial adhesion, increased crystallinity, thermal and mechanical performance. Moreover, the overall migration level assayed in a fatty food simulant was below the migration limits required for food packaging materials and showed effective antioxidant activity. Thus, these bionanocomposites show great potential as non-migration antioxidant materials with interest in the sustainable food packaging field.