A multiscale strategy to fabricate tough and highly flame-retardant bamboo-based cellulose bioplastics

Bamboo cellulose exhibits excellent biocompatibility and renewability, making it a promising alternative to conventional non-renewable petroleum-based resources. However, the inherent trade-off between strength and toughness, together with the flammability of cellulose, poses significant challenges for the development of bamboo cellulose-based films that simultaneously exhibit high strength, high toughness, and flame retardancy. In this study, a multiscale strategy involving deep eutectic solvent treatment is employed to deconstruct, modify, and reconstruct the bamboo cellulose network, thereby transforming it into a high-performance bioplastic. First, phosphorylated cellulose fibers with different size scales were prepared using a reactive ternary deep eutectic solvent. Subsequently, a film was successfully constructed via a micro/nano scale design strategy involving the physical entanglement of cellulose microfibrils and the physical filling of cellulose nanocrystals. The resulting film exhibits high strength (82.32 MPa), high toughness (20.05 MJ m^-3), excellent flame retardancy (LOI = 62.17%), as well as outstanding thermal stability, biodegradability, and recyclability, outperforming most reported cellulose-based flame-retardant films. This study demonstrates the significant promise of bamboo biomass as a sustainable substitute for petroleum-derived materials, thereby advancing the transition toward high-value applications of bamboo cellulose.