In keeping with nature - self-healing materials

Even broken bones grow back together. But in the case of steel, concrete and plastics, damage worsens over time and then requires laborious repair work. Currently only a few materials exist that can repair small defects by themselves, but this could change. Since 2011, a team headed by Dr. Andreas Wischnewski and Dr. Wim Pyckhout- Hintzen at the Jülich Centre for Neutron Science (JCNS) has been working with researchers from Germany and the Netherlands in the DFG’s priority programme “Design and Generic Principles of Self-healing Materials” in order to understand self-healing processes in materials and to develop them for practical applications. Their colleague Dr. Ana Bras is working at Jülich mainly on self-healing plastics. These consist of long molecular chains, or polymers, which are composed of smaller structural units. When the bonds between these molecules are optimally configured, small defects close as if by themselves. Using neutron scattering experiments, the Jülich researchers have ascertained the role that hydrogen bonds play in this process. They have shown that the chain-like molecules are loosely connected to each other via multiple hydrogen bonds. “These bonds can be broken and re established,” explains Bras. “They form a mesh. When it breaks, it can remesh itself anew.” This capability represents a decisive advantage over self-healing products that already exist, such as bicycle tyres that release a viscous substance when punctured and seal a hole. This feature of the tyre only works once in a particular spot. Jülich researchers are aiming to design materials that can grow back together repeatedly so that one day we’ll be able to say: A scratch in the paintwork? A crack in the seal? No need to worry – it’ll heal in no time!

Forschungszentrum Jülich/red.