Engineering Mechanically Strong and Bioactive Gelatin-Based Supramolecular Plastics via Hydrogen Bonding and Coordination Interactions for Food Packaging

Developing high-performance biopackaging is crucial for mitigating plastic pollution and advancing a sustainable circular economy. Guided by a supramolecular design strategy, this work presented a novel, mechanically strong, and bioactive gelatin-based composite plastic film constructed by sequentially incorporating carboxylated cellulose nanofibers (CCNF), gallic acid (GA), and Al3+, forming a multicross-linked network. The rigid CCNF phase drastically enhanced surface hydrophobicity (water contact angle: 113.9°). GA incorporation achieved near-complete DPPH/ABTS+ free radical scavenging (∼100%), validated by practical blueberry preservation, and increased elongation at break by 384%, indicating a brittle-to-ductile transition. Subsequent Al3+ coordination further strengthened the composite film, yielding a tensile strength of 28.7 MPa and a Young's modulus of 828 MPa. The final multicross-linked film (GCGAF) exhibited excellent thermal stability, robust gas barrier properties, notable antibacterial activity, and favorable biodegradability. This work provides an effective strategy for fabricating high-performance gelatin-based supramolecular plastics with balanced and superior properties for practical packaging applications.