Scientists create self-healing material

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A transparent, self-healing, stretchable, conductive material has been developed by scientists at the University of California, Riverside and the University of Colorado, Boulder. The material can be activated electrically to power artificial muscles and could be used to improve batteries, electronic devices and robots.

The researchers claim the findings represent the first time scientists have created an ionic conductor that is transparent, mechanically stretchable, and self-healing.

"Creating a material with all these properties has been a puzzle for years," said Chao Wang, an adjunct assistant professor of chemistry at Riverside.

According to the scientists, the key difficulty in self-healing is the identification of bonds that are stable and reversible under electrochemical conditions. Conventionally, self-healing polymers make use of non-covalent bonds, which are affected by electrochemical reactions that degrade the performance of the materials.

The team solved the problem by using a mechanism called ion-dipole interactions, which are forces between charged ions and polar molecules that are stable under electrochemical conditions. They attained this by combining a polar, stretchable polymer with a mobile, high-ionic-strength salt.

The low cost, rubber-like material can stretch to 50 times its original length. After being cut, it is said to completely re-attach in 24 hours at room temperature.

The material could be used to power an artificial muscle. After parts of the artificial muscle were cut into two separate pieces, the material is said to have healed without relying on external stimuli and to have returned to the same level of performance as before being cut.

The material could allow robots to self-heal after mechanical failure; extend the lifetime of lithium ion batteries used in electronics and electric cars; and improve biosensors used in the medical field and environmental monitoring.