Scientists from Singapore's Nanyang Technological University and the California Institute of Technology (Caltech) in the US have developed a new type of ‘chainmail’ fabric that is flexible like cloth but can stiffen on demand. The lightweight fabric is 3D-printed from nylon plastic polymers and comprises hollow octahedrons that interlock with each other.

When encased in a plastic envelope and vacuum-packed, it becomes 25 times more rigid and can hold up over 50 times its own weight. In specific physics terms, its capabilities are enabled by what's known as a jamming transition, the same principle that causes vacuum-sealed rice or beans to stiffen when packed up tight, leaving the particles with little room to move.

When manipulated into a flat table-like structure, the fabric was capable of holding loads of 1.5 kg.

In another test, a small steel ball was dropped onto the fabric when it was relaxed, which saw it deform by up to 26 mm; and then dropped again when it was rigid, which only deformed it by 3 mm.

The scientists then 3D printed a version of the material using aluminum, which they found to have the same pliability and softness of the nylon version. But when "jammed" together, the material proved much stiffer, owing to the hardier attributes of aluminum compared to nylon.

Where a plastic envelope was used to encapsulate the nylon version, the team imagines this metallic version could be encapsulated with Kevlar to form a protective fabric for bulletproof vests. Other potential applications for either version include exoskeletons, adaptive casts that change stiffness as the patient heals, or even bridges that can be rolled out and stiffened on demand.

The team is now working to improve the performance of the material, and is investigating new ways it might be stiffened, with magnetism, temperature and electricity among the possibilities. This research was published in the journal Nature.