PITTSBURGHConventional rules of survival tend to favor the strongest, but University of Pittsburgh-based researchers recently found that in the emerging world of self-healing materials, it is the somewhat frail that survive.
The team presents in the journal Langmuir a new model laying out the inner workings of self-healing materials made of nanoscale gel particles that can regenerate after taking damage and are being pursued as a coating or composite material. Moreover, the researchers discovered that an ideal amount of weak bonds actually make for an overall stronger material that can withstand more stress.
Although self-healing nanogel materials have already been realized in the lab, the exact mechanical nature and ideal structure had remained unknown, explained Anna Balazs, corresponding author and Distinguished Professor of Chemical Engineering in Pitt's Swanson School of Engineering. The team's findings not only reveal how self-healing nanogel materials work, but also provide a blueprint for creating more resilient designs, she said. Balazs worked with lead author and Pitt postdoctoral researcher Isaac Salib; Chet Gnegy, a Pitt chemical and petroleum engineering sophomore; German Kolmakov, a postdoctoral researcher in Balazs' lab; and Krzysztof Matyjaszewski, a chemistry professor at Carnegie Mellon University with a special appointment in Pitt's Department of Chemical and Petroleum Engineering.
The team worked from a computational model Gnegy, Kolmakov, and Salib created based on a self-healing material Matyjaszewski developed known as nanogel, a composition of spongy, microscopic polymer particles linked to one another by several tentacle-like bonds. The nanogel particles consist of stable bondswhich provide overall strengthand labile bonds, highly reactive bonds that can break and easily reform, that act as shock absorbers.
The computer model allowed the researchers to test the performance of various bond arran
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