Bioinspired Fiberboard-and-Mortar Structural Nanocomposite Based on Ultralong Hydroxyapatite Nanowires with High Mechanical Performance

Abstract Natural materials have enlightened us to assemble brittle building blocks into specific architectures with both high strength and toughness. As the main inorganic component of the bone and tooth, hydroxyapatite (HAP) materials have a high biocompatibility, but usually have a high brittleness. It is still a big challenge to artificially prepare biomaterials with the combination of high strength and high toughness, similar to natural materials constructed with brittle HAP building blocks. In this work, considering that enamel and nacre are typical examples of natural biomaterials with high strength and high toughness, respectively, we combine the structural merits of both enamel (highly ordered bundles) and nacre (brick-and-mortar structure) to construct a new kind of highly ordered ultralong HAP nanowire fiberboard-and-mortar alignment hierarchical structure (HFMAS) by the multiscale and multilevel assemblies of ultralong HAP nanowires from the nanoscale to microscale to macroscale and from one-dimensional (1-D) to 2-D to 3-D levels. The as-prepared hierarchical HFMAS nanocomposite can achieve a confluence of strengthening and toughening mechanisms of enamel and nacre, and exhibits superior mechanical properties such as high strength (308 MPa), Young's modulus (34.7 GPa), and toughness (4.77 MPa·m1/2), which are far better than those of many synthetic HAP-organic composites and other materials reported in the literature. Moreover, the as-prepared HFMAS nanocomposite exhibits a low density (1.8 g cm–3), good resistance to great impact, good damping capacity and durability. The as-prepared HFMAS nanocomposite is promising for various applications such as the protective armor, mechanical damping, and building materials.