A composite thread with a structure inspired by nacre — the iridescent material found inside many seashells — is the strongest graphene-based fibre ever made.

Credit: ADV. MATER.

Such fibres are typically produced by spinning together nanometre-thick sheets of graphene oxide. But they often have poor tensile strength, probably owing to weak interactions between the nanosheets. To strengthen the threads, Qunfeng Cheng of Beihang University in Beijing and his colleagues added two more ingredients: calcium ions and a flexible carbon compound called PCDO. These help to bind the nanosheets together, mimicking the strong interactions in nacre. The team produced a fibre roughly 20 micrometres wide (pictured) that could be tied in a knot without fracturing and could support a 2-gram weight.

The fibres also conduct electricity, making them a promising material for flexible electrodes or artificial muscles.

Adv. Mater. http://doi.org/f3k23w (2016)