Reverse gear makes metamaterial stand out

Engineers have made a metamaterial that can change its shape and properties, then fully return to its original configuration on demand.

Metamaterials have properties that do not occur in natural materials. However, these properties are typically fixed.

Now, Howen Lee from the State University of New Jersey, US, and his colleagues have used 3D printing to make a shape memory polymer lattice out of acrylic acid crosslinked with bisphenol A ethoxylate dimethacrylate that is both geometrically reconfigurable and mechanically tunable.

The material can be squashed to fit into tiny spaces, yet regains its original shape when heated, a property that would be useful in implantable medical devices.

Adaptive wing designs in aeronautics could also benefit from the material’s ability to switch between a rigid protective mode and a compliant shock-absorbing mode. Furthermore, it supports 300 times its own weight with minor deformation and can then be distorted into a new configuration by being bent or twisted at high temperature. The new shape can withstand the same load and be completely returned to its original configuration upon heating. Creating a material with properties such as these, which are also reversible, is unprecedented.