- A material that is able to self-repair even when it is sliced in two has been invented by French researchers.
The as-yet-unnamed material - a form of artificial rubber - is made from vegetable oil and a component of urine.
The substance, described in the journal Nature, produces surfaces when cut that retain a strong chemical attraction to each other.
Pieces of the material join together again as if never parted without the need for glue or a special treatment.
This remarkable property comes from careful engineering of the molecules in the material.
The French researchers are already making kilogramme quantities in their Paris laboratories and say the process is almost completely green, and could be completely so with a few adjustments.
The secret of the substance lies in how the molecules are held together.
A piece of normal rubber, says Dr Ludwik Leibler, who headed the research, is actually a single molecule with billion upon billions of smaller units chemically welded together to form a giant tangled network.
The elasticity comes from the fact that the strands within the network are buckled like a concertina: pull on them and they straighten and elongate; let go and the buckles reappear.