New composites that can regenerate when damaged

When a cell phone cracks or furniture breaks, these must be repaired or some parts replaced. But the possibility of putting materials that can regenerate themselves to replace the damaged or missing parts has become closer, with promises to reduce costly repairs and extend product lifetime.  

Such potential is now possible according to researchers at the University of Pittsburgh Swanson School of Engineering, who were able to develop computational models to design a new polymer gel that would enable complex materials to regenerate themselves.

Principal investigator is Anna C. Balazs, PhD, the Swanson School's Distinguished Robert v. d. Luft Professor of chemical and petroleum engineering, and co-authors are Xin Yong, PhD, postdoctoral associate, who is the article's lead author; Olga Kuksenok, PhD, research associate professor; and Krzysztof Matyjaszewski, PhD, J.C. Warner University Professor of Natural Sciences, department of chemistry at Carnegie Mellon University.

"This is one of the holy grails of materials science," noted Dr. Balazs. "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 research team was inspired by biological processes in species such as amphibians, which can regenerate severed limbs. This type of tissue regeneration is guided by three critical instruction sets -- initiation, propagation, and termination -- which Dr. Balazs describes as a "beautiful dynamic cascade" of biological events.

"When we looked at the biological processes behind tissue regeneration in amphibians, we considered how we would replicate that dynamic cascade within a synthetic material," Dr. Balazs said. "We needed to develop a system that first would sense the removal of material and initiate regrowth, then propagate that growth until the material reached the desired size and then, self-terminate the process."

"Our biggest challenge was to address the transport issue within a synthetic material," Dr. Balazs said. Biological organisms have circulatory systems to achieve mass transport of materials like blood cells, nutrients and genetic material. Synthetic materials don't inherently possess such a system, so we needed something that acted like a sensor to initiate and control the process.

The team developed a hybrid material of nanorods embedded in a polymer gel, which is surrounded by a solution containing monomers and cross-linkers (molecules that link one polymer chain to another) in order to replicate the dynamic cascade. When part of the gel is severed, the nanorods near the cut act as sensors and migrate to the new interface. The functionalizNike Womens Shoes