Tough, Bio-Inspired Hybrid Materials

Abstract

The notion of mimicking natural structures in the synthesis of new structural materials has generated enormous interest but has yielded few practical advances. Natural composites achieve strength and toughness through complex hierarchical designs extremely difficult to replicate synthetically. Here we emulate Nature's toughening mechanisms through the combination of two ordinary compounds, aluminum oxide and polymethylmethacrylate, into ice-templated structures whose toughness can be over 300 times (in energy terms) that of their constituents. The final product is a bulk hybrid ceramic material whose high yield strength and fracture toughness (~200 MPa and ~30 MPa√m) provide specific properties comparable to aluminum alloys. These model materials can be used to identify the key microstructural features that should guide the synthesis of bio-inspired ceramic-based composites with unique strength and toughness.With the quest for more efficient energy-related technologies, there is an imperative to develop lightweight, high-performance structural materials that possess both exceptional strength and toughness. Unfortunately, these two properties tend to be mutually exclusive and the attainment of optimal mechanical performance is invariably a compromise often achieved through the empirical design of microstructures. Nature has long developed the ability to combine brittle minerals and organic molecules into hybrid composites with exceptional fracture resistance and structural capabilities (1-3); indeed, many natural materials like bone, wood and nacre (abalone shell) have highly sophisticated structures with complex hierarchical designs whose properties are far in excess what could be expected from a simple mixture of their components (2,4). Biological mineralized composites, in particular bone, dentin and nacre (5-7), can generate fracture toughness (i.e., resistance to the initiation and growth of a crack) primarily by extrinsic toughening mechanisms (8) that "shield" any crack from the applied loads. These mechanisms, which are quite different to those that toughen metals for

Structure and mechanical properties of selected protective systems in marine organisms

“…While these materials are simple, they are combined in a significant level of complexity. This can often allow for mechanical performance which exceeds that of the individual constituents [9]. Focusing on marine organisms, the mechanical properties of biological material constituents (Table 1) and a variety of biological materials (Table 2) are highlighted.…”

“…Given its presence in the bones and teeth of humans, it has garnered a significant amount of research in the biomedical field, producing a number of bioinspired designs with a focus on biomedical materials and implants [9,[57][58][59][60][61]. Biogenic hydroxyapatite often forms around a collagen scaffold that directs growth (Fig.…”

“…Of additional importance, the cases of abalone and conch both show an increase in strength of~50% at high strain rates that are more representative of the crushing bites of predators [102,104]. Given the success of this system in the natural world, it has led to bioinspired designs of ceramics with toughness that surpasses that of their monolithic equivalents [9,108].…”

“…2 shows some examples) offer an amazing array of traits and properties due to the design of their complex biological materials. The lessons learned from the structural biological materials of marine organisms have stimulated a number of bioinspired designs including high toughness materials inspired by abalone nacre [9], fiber optic wires inspired by sea sponge spicules [10,11] and body armor inspired by fish scales [12,13]. Given the complex structures that have already been discovered and the immense number of organisms that have yet to be investigated, the study of structural biological materials of marine organisms offers much interest to the scientific community.…”

3D Printing of Lotus Root‐Like Biomimetic Materials for Cell Delivery and Tissue Regeneration

“…By imitating the specific hierarchical structures and synthetic process of the corresponding organisms from nanoscale to microscale, scientists have synthesized various materials with special structures and novel properties,1, 2, 3, 4, 5 such as ultrastrong and stiff layered composites inspired by nacre,6, 7, 8, 9, 10, 11, 12 high adhesion materials,13, 14 and other special biomimetic materials 15, 16, 17, 18, 19, 20, 21. Taking advantage of the wisdom of natural organisms, smart materials with improved properties have been prepared and used in many fields.…”