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Anyone who has ever smashed their iPhone's screen or depleted a battery knows that devices are destined to deteriorate and eventually die. But
what if they could one day heal themselves? That's the vision
Chao Wang, a polymer researcher and assistant professor in the chemistry department at the University of California, Riverside has for the future — and he helped invent a super-stretchy, self-healing polymer that could one day make it possible.
Together with colleagues at Stanford University, Nanjing University in China, and other institutions, Wang helped create a synthetic polymer that acts in some astonishing ways. In
a recently published article in Nature Chemistry, they describe a
material that can stretch to 100 times its own length — then make its way back to its original state. And when cut or punctured, it puts itself back together again.Those qualities sound futuristic, but Wang says they're simply inspired by nature. "Our human muscles are healable," he says. "Scientists have been trying to introduce these properties to manmade materials."
Polymers that mend themselves using microcapsules filled with healing agents already exist, points out Wang,
but once those microcapsules are punctured, more repairs can't be performed — and the material can't stretch to its limits again.To achieve a substance that could heal itself again and again, Wang and his colleagues relied on
crosslinking, a chemical process that links long and short chains of molecules together in a kind of fishnet pattern. As the polymer stretches, its dynamic, relatively weak, and short hydrogen bonds break but don't destroy the longer, stronger bonds. When the stress ends, the atoms in the short chains reorganize and reform the dynamic, weaker bonds, thus "healing" the material. Nanoscale nickel added to the polymer adds even more strength and allows the polymer to conduct electricity.
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