A review of nacre-inspired materials: Chemistry, strengthening-deformation mechanism, synthesis, and applications

Biomimetic material development takes inspiration from biological materials and organisms that possess extraordinary properties or appearance, such as excellent mechanical strength and toughness, self-cleaning, self-healing, brilliant colours, etc., to develop materials and products with advanced capabilities. One such remarkable inspiring source is nacre which forms the inner layer of shells and is commonly known as the mother of pearls. Nacre consists of 95 vol% brittle inorganic minerals (CaCO3), and 5% organic polymers as the brick-and-mortar structure, yet exhibits a work of fracture that is ca. 3000 times higher than that of pure constituent minerals. Mimicking nacre, an ideal combination of high strength, and high fracture toughness, paves the way for the production of alternative, sustainable high performance, structural and functional materials. Recent research advances have led to the fabrication of nacre-inspired hierarchical structured fibres, films, and bulk composite materials. This review discusses the chemistry of nacre formation, the details of brick-and-mortar structure, and the strengthening and deformation mechanism. Furthermore, we present a broad overview of recent trends and developments in synthesis processes and applications of nacre-inspired materials. We put emphasis on hierarchical composites with a brief discussion on artificial carbonates synthesized by mimicking the natural formation of nacre.