“This is one of the holy grails of materials science,” said Anna C. Balazs, PhD, principal investigator on the project. “While others have developed materials that can mend small defects, there is no published research regarding systems that can regenerate bulk sections of a severed material. This has a tremendous impact on sustainability because you could potentially extend the lifetime of a material by giving it the ability to regrow when damaged.”
The team studied amphibians' ability to regrow limbs that had been severed and found that in order for a synthetic material to do the same, three processes had to occur: initiation -- where the material senses the loss of material and the need to regrow it, propagation -- where the material actually regrows, and termination -- where the process self-terminates when the correct size and shape has been reached.
The team developed a hybrid material made of nanorods embedded in polymer gel. The nanorods act as sensors in the gel so when it's cut, the nanorods migrate to that site which sets off a polymerization reaction with an outer solution that starts the repair and forms the replacement gel.
Next up is to strengthen the bonds between the old and newly formed gels, and they're taking notes from the giant sequoia tree. “One sequoia tree will have a shallow root system, but when they grow in numbers, the root systems intertwine to provide support and contribute to their tremendous growth,” Dr. Balazs explains.
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