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KIT and Evonik researchers develop novel polymer network that self heals rapidly and repeatedly at relatively low temperatures

Scientists of the Karlsruhe Institute of Technology and Evonik Industries have developed a chemical cross-linking reaction that ensures good short-term healing properties of a polymer material under mild heating. The research results have been published in the journal Advanced Materials.

The KIT group headed by Christopher Barner-Kowollik uses the possibility of cross-linking functionalized fibers or small molecules by a reversible chemical reaction for the production of self-healing materials. These “switchable networks” can be decomposed into their initial constituents and reassembled again after the damage. The advantage is that the self-healing mechanism can be initiated any time by heat, light or by the addition of a chemical substance. The method requires no catalyst or additive, said Professor Barner-Kowollik, Chair for Preparative Macromolecular Chemistry at KIT.

It took about four years of research for the working group of Barner-Kowollik, together with the Project House Composites of Creavis, the strategic innovation unit of Evonik, to develop a novel polymer network.

Reducing the time needed for healing and optimizing the external conditions, under which the healing process takes place, are major challenges for self-healing materials. At comparably low temperatures from 50°C to 120°C, the network exhibits excellent healing properties within a few minutes.

The KIT researchers have found a large number of intermolecular compounds that close again within a very short term during cooling. Mechanical tests, such as tensile and viscosity tests, confirmed that the original properties of the material can be restored completely.

The self-healing properties can be transferred to a large range of known plastics. In addition to self-healing, flowability is enhanced at higher temperatures—i.e., the material can be molded well. A potential field of application lies in the production of fiber-reinforced plastics components for automotive and aircraft industries.

Resources

  • Oehlenschlaeger, K. K., Mueller, J. O., Brandt, J., Hilf, S., Lederer, A., Wilhelm, M., Graf, R., Coote, M. L., Schmidt, F. G. and Barner-Kowollik, C. (2014) “Adaptable Hetero Diels–Alder Networks for Fast Self-Healing under Mild Conditions,” Adv. Mater.. doi: 10.1002/adma.201306258

Comments

HarveyD

Interesting for molded self healing reinforced plastic future e-vehicles for junior?

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