Abstract
Bio-based plastics offer the advantage of biodegradability over traditional petroleum-based plastics, enabling natural reintegration into the environment and positioning them as a more sustainable alternative. DNA, as a natural biopolymer, exhibits excellent biocompatibility and degradability. However, the mechanical strength of currently biomass DNA-based materials is inferior to that of other bio-based and petroleum-based plastics. In this work, DNA plastics with a ″brick-and-mortar" structure were fabricated using DNA extracted from onions through bidirectional freezing, water vapor annealing, and compression densification. This biomimetic design significantly enhances the fracture toughness (∼1.5 MPa·m(1/2)) while possessing a high elastic modulus (∼560 MPa) of DNA plastic, making it superior or comparable to existing bio-based plastics and petroleum-based plastics, and thus positioning it as a potential structural material. Analysis of crack propagation behavior in DNA plastics reveals that their high toughness stems from a hierarchical ″brick-and-mortar″ structure operating across multiple length scales, facilitating a multiscale fracture process from macroscopic to molecular levels. Furthermore, these DNA plastics can be efficiently recycled in aqueous environments and fully biodegraded by enzymes, demonstrating strong environmental friendliness and significant potential for sustainable development.