PARIS - A chemistry professor in Paris has come up with a kind of rubber that can "heal'' itself.
Ludwik Leibler says his rubber can be stuck back together if it is torn, then used over and over.
The self-healing rubber was concocted in his lab at the Industrial Physics and Chemistry Higher Educational Institution and details of his research are found in the science journal Nature.
Leibler and his colleagues built up their rubber from simple starting materials including vegetable oil and urea, a component of urine. The resulting material is a cross between silly putty and a rubber ball with applications ranging from adhesives to bicycle tires.
Leibler's team explained how their compound differs from regular rubber. Regular rubber is made of a single, continuous, stretchy molecule, held together with strong chemical links called covalent bonds. Once these bonds are cut by a break in the material, the rubber can't be reassembled.
Leibler's approach was to use small molecular groups instead, as in the fatty acids from vegetable oil. Reacting these molecules with urea in a two-step process stuck nitrogen-containing chemical groups onto the ends of the fatty acids. The fatty acids link to each other using a hydrogen bond. That is a strong attractive force between hydrogen and another atom, and the bond responsible for holding water molecules to each other.
The resulting molecular system is very non-uniform, meaning some acids have three protruding groups and some have two. This means that the compound can't crystallize into a hard, shatterable material.
Leibler has struck a deal with a French chemical company to develop and commercialize the material and said he would like to see the rubber used in toys.
"Children like to break things -- if you could heal them it would be very nice,'' he said.
