Auxetic polymer networks

Towards materials with auxetic behavior at the molecular scale

Project leader: A. Kilbinger

Team: C. Weder, K. Fromm

Auxetic materials expand perpendicular to the direction in which they are stretched and vice versa. In Nature, this phenomenon is observed in certain metals or crystals such as twinned iron pyrite or a-cristobalite, and in the last years several synthetic materials with auxeticety have been reported on the microscopic and macroscopic scales. These include polymeric foams and microporous polymers which can lower their overall (apparent) density via gas exchange with the surrounding atmosphere, and molecular auxetics that are typically based on a change in the packing efficiency of the constituting material, i.e. the creation of voids in order to expand perpendicularly upon stretching. However, no intrinsic (molecular) auxetic behavior has so far been achieved with synthetic polymeric materials. From this standpoint, the goal of this project is the development of intriscically auxetic materials using covalent polymer networks.

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Involved people