Design And Fabrication Of High-Performance Biomimetic Structural Materials Based On Micro/Nanoscale Building Blocks

Natural structural materials,although composed of relatively fragile inorganic mineral components(such as calcium carbonate,calcium phosphate and silica)and a small amount of soft organic polymers(such as protein and polysaccharide),often exhibit amazing mechanical properties far beyond its own components due to their exquisite hierarchically ordered structure and interfacial design.These hierarchical structures and mechanical properties achieved by limited material composition under mild conditions,make natural biologically structural materials more and more model materials systems pursued by materials scientists and engineers.Researchers analyze the multiscale structure of natural materials and correlate the excellent properties,extract the biomimetic principle,use rich synthetic building blocks,develop biomimetic assembly strategies,and expect to design new-style high-performance biomimetic structural materials that replace the existing engineering materials.In recent years,great advances have been made in the design and preparation of biomimetic materials.However,it is still challenging to construct practical three-dimensional bulk biomimetic structural materials and simultaneously to accurately design and control their micro/nano structures or interfaces at the macroscopic scale.The application and further promotion of high-performance macroscopic three-dimensional bulk biomimetic structural materials face many key scientific and technical problems.The development of highly efficient,low-energy and environmentally friendly biomimetic assembly and interfacial design strategies will help accelerate the practical pace of the advancement of biomimetic structural materials and has attracted widespread attention.In this dissertation,we first analyze the fundamental building blocks,multiscale architectures and performance of natural biomaterials including fish scale(Arapaima gigas),dactyl club(Odontodactylus scyllarus),bone and nacre,and then review the progress of biomimetic structural materials in terms of building blocks and design strategy in recent years.Based on this,we further develop several universal and efficient biomimetic assembly and interfacial design strategies inspired by a variety of biologically structural materials,and carry out biomimetic assembly and majorization of one-dimensional and two-dimensional micro/nanoscale structural units at macroscale,in order to achieve controllable fabrication of high-performance biomimetic structural materials.The main achievements can be summarized as follows:1.Inspired by the micro/nanofiber-based twisted plywood structure and the strengthening/toughening mechanisms of natural Arapaima gigas fish scale,we developed a universal biomimetic assembly strategy that combines brushing and laminating,achieving flexible arrangement of one-dimensional micro/nanofibers on macroscale.Using hydroxyapatite mineral microfibers and sodium alginate biopolymer as fundamental constituents,we successfully replicated the multiscale plywood structure and mechanical mechanisms of natural materials to synthetic materials systems,and for the first time constructed macroscopic armor-like biomimetic structural materials with high damage tolerance.2.Inspired by the "brick-and-mortar" layered structure and strengthening/toughening mechanisms of natural nacre,we developed a scalable fabrication strategy for high-performance,three-dimensional large-sized and fine-structured biomimetic nacre-like composites based on two-dimensional micro/nanosheets building blocks.This multilevel biomimetic assembly strategy has the advantages of mildness,flexibility,high efficiency,scalability and universality,and lays a methodological foundation for the design and preparation of advanced biomimetic structural materials that are truly practical for applications.3.Inspired by the multi-level interfacial design and superior performance of natural nacre,we proposed a multiscale polymer-based soft-rigid dual-network interfacial design concept.Using this concept,we can manipulate the interface microenvironment of ultrathin nanosheets building blocks in a mild and efficient biomimetic assembly process to precisely control the overall performance of the assembled macroscopic three-dimensional biomimetic nanocomposites.The multiscale interfacially optimized biomimetic nanocomposite exhibits excellent interface enhancement efficiency,mechanical properties,moisture resistance and thermal stability.The proposed soft-rigid dual-network interfacial design strategy is mild and versatile,providing a novel approach to construct more high-performance biomimetic structural materials.