Bio-inspired nacre-like composites via simple, fast, and versatile techniques such as doctor-blading

Theoretical and experimental studies show that the high performance of biological composites such as nacre and bone originates from a sophisticated microstructure, where hard and stiff inclusions form a staggered, brick wall-like structure within a softer and more deformable matrix. This morphology results in outstanding combinations of stiffness, strength and toughness, and therefore it is very attractive to duplicate it in engineering composites. Here, we demonstrate how simple, fast and versatile techniques such as doctor-blading can be used to make such bio-inspired composites. We fabricated and characterized composites made of micron-sized alumina tablets embedded in epoxy matrices. Scanning Electron Microscopy (SEM) images show that the tablets are well dispersed, aligned, and staggered through the polymer matrix resulting in a nacre-like material. The tensile behavior of these composites shows a good combination of stiffness, strength and energy dissipation. We also developed finite element models of the staggered microstructure, which properly capture the interactions between inclusions and the effects of mineral concentration. These models can be used to optimize the microstructure and fully harness the nacre-like structure and mechanisms, in new materials with applications in aerospace, defense or biomedical engineering.