Molecular structure isoprene - basic block of natural rubber
Raimund14/Adobe Stock Molecular structure isoprene - basic block of natural rubber

A new type of rubber that can heal itself has been developed by researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). The study explains that while self-healing materials are not new, engineering these properties is more difficult in dry materials like rubber, a substance that is constructed from polymers held together by permanent covalent bonds that do not reconnect once broken and therefore cannot self-heal.

In the self-healing rubber, researchers reconnected these rubber bonds by mixing covalent and reversible bonds, and building a molecular rope—randomly branched polymers that allow two formerly unmixable bonds to mix—tying both kinds of bonds together so they can reform after being broken. The resulting transparent, hybrid rubber is as tough as natural rubber but instead of cracking under high stress, it forms crazes, or cracks connected by fibrous strands. These crazes redistribute the applied stress and are able to heal, allowing the rubber to return to its original form.

The rubber has the potential for a number of uses including tires, medical devices, and wearable technology. “Imagine that we could use this material as one of the components to make a rubber tire,” said Jinrong Wu, a collaborating professor from Sichuan University in China, in a news release by Harvard. “If you have a cut through the tire, this tire wouldn’t have to be replaced right away. Instead, it would self-heal while driving enough to give you leeway to avoid dramatic damage.”

A patent for the technology has been filed by Harvard’s Office of Technology Development, and the department is looking to commercialize the product.