Prominent Journals Feature Self-Healing Advances

2014-01-28

Aerospace Engineering at Illinois Prof. Scott R. White
Aerospace Engineering at Illinois Prof. Scott R. White
Recent advances Aerospace Engineering at Illinois Prof. Scott White’s group has developed in self-healing materials have led to cover features in two prestigious journals.

The research discussed in the January 15 issue and highlighted on the cover of Advanced Materials features White’s group investigation into increasing the efficiency of self-healing in polymers that are cured at high temperatures, from 121 to 177 degrees Celsius. Such materials are desired in consumer products requiring high strength and stiffness, low weight and environmental stability.

The materials that White’s group has developed mimic biological systems in promoting self-healing. The polymers are embedded with microcapsules that break and release reactants when a crack or fracture occurs. Reactants flow into the crack, fill it, and repair it. However, high temperatures increase the risk of premature reaction of the healing chemistry, undesirable side reactions, or degradation of the catalytic reactants.

White’s group has resolved the issue by isolating epoxy and amine reactants in separate polymeric microcapsules with excellent thermal stability. “Not only do you get increased efficiency,” White maintained, “prior to this work there was no self-healing system that could autonomically heal at room temperature after being subjected to high temperature curing cycles typical in advanced composites. This was a major advancement for us.”  

Contributing to this research have been White, alumnus Henghua Jin, MS 08 (Mechanical Sciences and Engineering), PhD 12 (AE); alumnus Chris L. Mangun, BS 90 (Ceramic Engineering), PhD 97 (Materials Science & Engineering), now at Champaign, IL-based CU Aerospace, LLC; Anthony S. Griffin, MatSE graduate student; Jeffrey S. Moore, Illinois chemistry professor, and Nancy R. Sottos, Illinois MatSE professor and AE affiliate.

The January 28 issue of Soft Matter shows how the scientists once again turn to biology to solve structural issues in microvascular networks for self-healing materials. The article and cover feature, “Structural Reinforcement of Microvascular Networks Using Electrostatic Layer-by-layer Assembly with Halloysite Nanotubes,” describes how White and his group seek to mitigate premature failure in unreinforced microchannels by inserting nanoscale skeleton-like structures into the materials.

“The skeleton provides a seamless way to integrate reinforcement into vascular materials so that you don't degrade their inherent mechanical properties during the process of vascularization,” White said. “In short, they are stronger and more robust materials with the method we show.”

In addition to White and Sottos, contributing to this project were Solar C. Olugebefola, formerly a postdoctoral research associate at the Beckman Institute for Advanced Science and Technology at the University of Illinois; alumnus Andrew R. Hamilton, MS 07, PhD 11, both Theoretical and Applied Mechanics, and currently a faculty member at Queen’s College in Belfast, Ireland; and Daniel J. Fairfield, a Northwestern University graduate student.