UKMMN Metamaterial Picture Competition 2022

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Image credit: Shruti Mandhani

One way to define a metamaterial is a material that exhibits properties not found in nature. This image represents a structure inspired by a natural metamaterial – Cellulose Ib. Cellulose Ib, specifically from Norway spruce aka a Christmas tree, is auxetic at the molecular level. In the X-Y projection shown, the beams along X represent cellobiose chains, whereas the connecting spacers along Y represent hydrogen bonds that connect neighbouring chains to form a sheet. This model is deformed along Y, and the colours represent displacements with blue being the least and red representing the highest displacement. The shaded/grey model in the background shows the un-deformed version of this system, thus showing its auxetic behaviour as expansion is observed along both X and Y directions. This model is part of a series of models developed to ultimately form a nature-inspired auxetic structure that derives its auxeticity from the molecular level. This would allow for chemical tuneability of such a material, thus finding applications in a wide range of sectors including automotive, biomedical, and aerospace.

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