Researchers in the US have been successful in developing tough, hybrid rubber that doesn’t crack. This means that car tyres that are punctured can be automatically repaired.

This breakthrough technology was developed by researchers from the Harvard John A Paulson School of Engineering and Applied Sciences (SEAS) in the US who created self-healing hydrogels, which depend on water to incorporate reversible bonds that can trigger the healing process.

It was a challenging task for the researchers as rubber is made of polymers often connected by permanent, covalent bonds. Once broken, these incredibly strong bonds cannot be reconnected. Therefore, they decided to make the bonds connecting the polymers reversible so that they reform on breaking.

Li-Heng Cai, a postdoctoral fellow at SEAS said that it was pretty challenging to make something tough that can self-heal. He and his team came up with a hybrid rubber with both covalent and reversible bonds. Cai said that these two types of bonds are intrinsically immiscible, like oil and water.

The two types of bonds were secured by a molecular rope developed by the researchers. This rope called randomly branched polymers, allows two previously unmixable bonds to be mixed homogeneously on a molecular scale. The result was a transparent, tough, self-healing rubber.