Advanced microscopic characterisation of multi-scale high-resolution mechanical behaviour of a nacre-inspired composite

A nacre-inspired composite with a lamellar architecture of polymethyl methacrylate (soft and tough phase) and alumina (stiff phase) was fabricated using a bidirectional freezing casting technique. The bulk fracture mechanics of the nacre-inspired composite has been reported along with detailed microstructural analysis. The mechanistic connection between microstructure and mechanical properties at the micro- and macro-scale was not fully understood. Herein we addressed this issue by quantifying phase-specific hardness, modulus, and residual stress at the micro-scale level and compared with the bulk mechanical response. A shear-lag model was applied to provide a quantitative understanding of the softening effects resulting from residual stress and the microstructure. Our findings demonstrated the potential of bioinspired synthetic architectures in providing a tuneable model system to investigate the underlying design principles of more complex hierarchical biological materials.