Abstract: Natural materials outperform traditional synthetic composites due to their elaborate and multiscale hierarchical architecture, resulting in improved mechanical performance. However, the manufacture of artificial natural structures remains challenging due to the limited process accuracy, multiscale of phase materials and high design complexity. Herein, we fabricate bioinspired graphene scaffolds with multiscale hierarchical structures using a stretching ink-induced three-dimensional (3D) printing strategy. This programmable design strategy enables precise control of the graphene nanosheet orientation within the continuous fibers. Further spatial arrangements of fibers construct various biomimetic structures, including bio-inspired brick-and-mortar, Bouligand and branch-lamellar architectures. Remarkable toughness and strength have been observed from the fabricated architectures, attributed to the prevention of crack initiation and propagation by graphene nanosheets. Furthermore, contrary to the previous mechanical anisotropy in natural composites like nacre-mimetic structure, our composites exhibit isotropic mechanical properties in all directions due to the multiscale hierarchical structures. This study provides a promising path for developing high-performance nanocomposites and designing unprecedented architectures.

Key words: 3D printing, Bioinspiration, Graphene-epoxy composites, Hierarchical structure, Mechanical properties