Large-area, high-strength cellulose nanocomposites enhanced by confined polymer nanocrystallization in Bouligand structures

Sustainable and biodegradable materials derived from biomass are appealing candidates to replace fossil-based materials. However, the mechanical performance of biomass is insufficient for practical applications. Here, inspired by fish scales, we report a strategy to construct large-area, high-strength cellulose nanocrystal (CNC) nanocomposites with confined polymer nanocrystallization in Bouligand structures. By regulating the electrostatic repulsion of CNCs, the spacing of nanorods was reduced from 8.8 ± 0.4 to 5.0 ± 0.3 nm, and the crystallinity of the interphase extended polymer chains was regulated within such a confined space. The resulting nanocomposite films exhibited a tensile strength of 456.6 ± 18.6 MPa. Moreover, the nanocomposite films could be laminated to bulk materials, which exhibit excellent fracture toughness of 7.1 ± 0.2 MPa m^1/2 and hardness of 6.1 ± 0.6 GPa while being light in weight. This efficient cellulose utilization strategy offered a promising pathway for the production of robust, biodegradable, and sustainable cellulosic bioplastics.