Coaxially printed biomimetic BSPC with high strength and toughness

The trade-off between strength and toughness in traditional silicate-based materials presents a notable challenge in engineering infrastructure. The limited range of suitable components means that chemical modification does not fully address inherent brittleness. This study introduces a novel coaxial 3D printing method to create tooth enamel biomimetic composites using stiff silicate and flexible polyvinyl alcohol (PVA) as strengthening and toughening agents, respectively. Unlike standard silicate composites, this method produces an interpenetrated microstructure in which silicate and PVA maintain geometric continuity. This biomimetic structure, regulated internal stress, and crack propagation inhibition contribute to the silicate–PVA composites considerably enhanced mechanical properties, including flexural strength (10.3 MPa), ductility (4.68 %), and fracture energy (1.5±0.9×10⁴N/m), beyond the inherent brittleness of pure silicate blocks. In situ characterization and multiscale simulation of stress distribution and deformation behavior further validated multiple toughening mechanisms. These mechanisms include silicate bridge fracture, interface detachment, and PVA rupture, along with complex cracking patterns. The significantly strengthened and toughened biomimetic silicate–PVA composite suggests promising potential for use as a structural material in engineering resilient structures.