Expanding under pressure
Usual materials tend to contraction when compressed and to expand when under tensile stress: they display positive compressibility. A group of researchers at DIMA ICI has shown, both theoretically and experimentally, how to obtain systems with the opposite behaviour, i.e., with negative compressibility. The proposed strategy exploits the use of bubbles dispersed inside elastic materials in order to pre-compress them while their destruction allows to relax the materials. The authors found reversible negative compressibility in nanoporous materials and even in some proteins, inspiring the realisation of metamaterials with the same characteristics.
This surprising behaviour open the way to realization of artificial muscles, acoustic cloaks and to compensate for the expansion of other materials.
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