Nacre-inspired composites with different macroscopic dimensions: strategies for improved mechanical performance and applications

To develop next-generation lightweight, high-strength, and tough materials, new materials design strategies must be established. Nacre, consisting of 95 vol.% inorganic plates (CaCO 3 ) and 5 vol.% organic matrix (protein) in layered arrangements, is famous for its significant increase (three orders of magnitude higher) in toughness compared to monolithic aragonite and has always been the model for the synthesis of high mechanical performance artificial materials. In this review, we primarily introduce the recent studies on the synthesis of nacre-inspired composites with exceptional mechanical properties, including 1D fibers, 2D films, and 3D bulk materials. In addition, design strategies for performance enhancement are summarized based on these studies, and applications of high-performance nacre-inspired composites are also discussed. Finally, a critical outlook of the future direction of developing next-generation high mechanical performance nacre-inspired composites is provided. Biomaterials: Coming out of their shell Sea shells provide the inspiration for super strong but lightweight materials. Lin Guo and colleagues from the Beihang University, China, review the various approaches for creating nacre-inspired composites. Nacre is formed of layers of calcium carbonate plates held together by an elastic biopolymer; like bricks held together by mortar. This structure makes it three orders of magnitude tougher than bulk calcium carbonate. Nature has harnessed these impressive mechanical properties to create mollusc shells. Fabricating nacre artificially on a large scale would offer a lighter alternative to alloys, plastics and ceramics. Guo and colleagues give an overview of the methods for fabricating one-dimensional nacre fibers, two-dimensional nacre films and three-dimensional nacre as well as strategies for enhancing their performance. They highlight the importance of promoting interface reactions and controlling the material’s microstructure. In this review, we overview the recent achievements in synthesis of high performance nacre-inspired macroscopic composites and divide them into different groups by standards of different dimensions, such as 1D nacre-inspired fibers, 2D nacre-inspired films and 3D nacre-inspired bulk composites. The methods to produce different dimensional nacre-inspired composites are also introduced and performance enhanced strategies for different dimensional nacre-inspired composites are summarized and explained in detail. Ap