Radical Repairing Rubber

Daniel Fulton, Gennady Malyshev, Emily Peck, Corey Zehfus

Rubber is one of the most useful substances produced in the modern world. Its high elasticity and relative ease of molding make it an ideal substance for a number of applications. Over 56 percent of the world’s rubber is used in tires and tubes, but a number of other products — such as adhesives, elastics in textiles, erasers, belts, gaskets, and construction materials for sealing doors and windows — are all heavily utilized rubber products.The elasticity of rubber comes from its chemical bonds. Rubber is made up of long chains of hydrocarbons. When rubber is stretched, chemical bonds are pulled out of their minimum energy states, and energy is stored in the material thermally and electrostatically. When the stress on the material is removed, the energy is released, and the bonds quickly return to their lower energy states, macroscopically resulting in a return of the material to its original shape. In nonelastic materials, bonds are simply broken by this stress, and the material separates into pieces.

In a recent edition of the journal Nature, a team of scientists in Paris writes that they have created a new rubber-like elastic material. In addition to having nearly the same elasticity as rubber, it has one new interesting property: the ability to “heal” itself. Instead of long hydrocarbon chains — single molecules — this new material is made up of much shorter chains, held together only by hydrogen bonds. As a consequence, when the material is broken, it can be held together and the hydrogen bonds will reform. After an extended time the cut or broken ends of the material will form bonds with itself, but the substance can be healed to itself any time in 15 days after being broken, and the process occurs at room temperature.

This interesting new material may prove very handy for any number of new applications.