What is it about?

In this paper, we studied mechanical properties of atomistically thin inorganic layers with tandem repeat proteins through fine control of their molecular weight. Mechanical properties are tunable and exceed state state-of-the-art composites, which cannot be explained by an existing theoretical model. This finding opens a perspective on failure mechanism for composites, which depends on interfacial rather than bulk properties. Controlling interfacial strength ultimately engender new design rules for nature-inspired composites.

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Why is it important?

Various life forms on Earth sequester carbon (e.g., shell-building marine animals) by combining proteins and inorganic layered composites. As the carbon dioxide dissolve in the sea as carbonate ions, exoskeleton creatures (such as Coccoliths or mother of pearl) build their shells by converting carbonate to calcite (preferred) or aragonite (kinetically limited). Biology does this 1000 times faster than natural calcite transformation. Normally this calcite conversion reaction takes place over 10,000 years in rocks and rivers (albeit it is thermodynamically preferred). Natural organisms do not live that long, and inevitably they have to do it 1000 times faster. These shells become insensitive to mechanical flaws as soon as its size reaches a critical length scale.

Perspectives

Nature creates layered materials like bone and mother-of-pearl that become less sensitive to defects as they grow. Now researchers have created, using biomimetic proteins patterned on squid ring teeth, composite layered 2D materials that are resistant to breaking and extremely stretchable.

melik demirel
Pennsylvania State University

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This page is a summary of: Bioinspired stretchable molecular composites of 2D-layered materials and tandem repeat proteins, Proceedings of the National Academy of Sciences, July 2022, Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.2120021119.
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