A Soy Protein-Based Composite Film with a Hierarchical Structure Inspired by Nacre

Soy protein-based composite film is a potential replacement for petroleum-based film with multipurpose applications and cleaner production. It is difficult to improve both the tensile strength and toughness of a protein-based film without sacrificing its elongation. In this study, inspired by the hierarchical structure of nacre, a facile yet delicate strategy was developed to fabricate a novel bio-based film with excellent toughness and high strength. Triglycidylamine (TGA) crosslinked soy protein (SPI) as hard phase and thermoplastic polyurethane elastomer (TPU) as soft phase comprise an alternative lay-up hierarchical structure. The interface of these two phases is enhanced using triglycidylamine (TGA) surface-modified TPU (MTPU). The tensile strength of SPI/MTPU/TGA films increases by 392% to 7.78 MPa and their toughness increases by 391% to 8.50 MJ/m3 compared to soy protein/glycerol film. The proposed hierarchical structure can also be extended to other high-performance materials and polymers.