Protein crystals stretch knowledge of exotic materials

It may seem like a bit of a stretch, but scientists in the US have designed a protein crystal sheet that thickens when it is stretched and shrinks when compressed.

From elastic bands to pizza dough, most man-made materials tend to thin as they are stretched. The opposite is true when they are under compression, with material flowing away from the source of pressure and expanding in the opposite direction. Scientists describe this effect using Poisson’s ratio, a term that compares the strain in the plane of an applied force to the transverse strain. In the case of elastic bands, dough and a whole host of other materials, the ratio is positive. But there are cases when this ratio is negative and a material will shrink as it’s compressed – a peculiar property known as auxeticity.

Now, Tezcan and his colleagues have made such an auxetic material at the molecular scale.

This article links to coverage by Chemistry World.