Nancy Sottos was one of the lucky ones. Right after she received her Ph.D. in mechanical engineering in 1991 from the University of Delaware, she was asked to teach at the University of Illinois, and shortly after, began pursuing research at the Beckman Institute. Nowadays, a career in research and teaching is difficult to do without a postdoctoral fellowship, but Sottos’ passion for and excellence in collaborative research, Beckman’s staple requirement, was evident.
For her graduate studies, she worked with a team in a center for composite materials at the University of Delaware, so “it’s not a surprise I wound up in a collaborative team. That’s initially how I was trained to do research,” Sottos said.
It wasn’t long after she arrived at U of I that she started talking with Scott White about combining their efforts to work with autonomous materials. They quickly recruited Jeff Moore, and together, they created the Autonomous Materials Systems Group in 2001, one of the longest-standing groups at Beckman, which Sottos says sits at the intersection of materials, chemistry, and mechanics.
“In this group we’re focused around some central themes,” Sottos said. “We’re inspired by biological systems and all the functions of it, in either plants or animals, and we’re trying to reproduce these functions synthetically. We’re trying to develop materials systems capable of self-healing, self-sensing, and self-cooling responses.”
One application of self-cooling and self-healing concepts is through batteries, an integral part of many ubiquitous gadgets, such as laptops, cell phones, and battery-powered cars.
“Batteries have significant reliability and safety issues,” explained Sottos. “Nobody wants a heavy battery or one that’s too large, especially in cell phones or electric cars. The way to make them smaller is to increase the density and capacity of the battery in order to store more energy. But as the energy density increases, they become unreliable and have greater potential for mechanical failures. A more serious issue is when they overheat, which is called ‘thermal runaway.’”
Thermal runaway has become a rather infamous problem in airplane mechanical issues. In planes, the lithium-ion batteries overheat, causing irreversible damage and requiring planes to make emergency landings.
Sottos’ group is looking at materials to shut down this problem of thermal runaway autonomously. One way is through an approach that creates a microcapsule of polymers that are triggered to melt when a battery reaches a specific temperature. When the polymers melt, they block the flow of ions, and the process that is causing the battery to “run away thermally” is shut down autonomously.
More recently, the group has been working on cooling concepts for the casing of a battery in order to keep the battery cool all the time, so shutting down the battery isn’t necessary. This would maintain optimal battery performance, instead of waiting for the battery to malfunction.
“We’ve also been trying to solve the issue of losing capacity in batteries,” Sottos said. “For example, after two years or so, laptop battery capacity fades, which especially makes an impact in an electric car. If the battery capacity fades in a car, it can’t go as many miles. So we’re working on autonomous materials to influence the chemistry and the mechanical reliability throughout the life of the battery. Self-contained components will release additives or try to restore conductivity where it’s been lost as the battery goes through its charge and discharge cycles.”
Sottos is able to conduct this complex research in labs she shares with White and Moore. Moore’s group works with the chemical side of the research, she says, like synthesizing polymers and healing chemistries. White’s group focuses on the processing of polymers and composites with the healing chemistries. In Sottos’ group, they specialize in the characterization of the various functions of polymers with capsules and vascular networks, as well as molecularly changing the architecture of the polymer or composite to enhance the healing or cooling response.
Her lab has facilitated her research, but she knows it’s been a team effort with White and Moore. Their successful and long-lasting collaboration has been integral in jointly contributing to the advancement of autonomous materials.
“Not only are the lab facilities unique to Beckman, but the proximity to my collaborators and my student researchers is really important,” said Sottos. “Our research program has also received great support from Beckman for grants. Finally, having access to the Microscopy Suite and the Visualization Lab has been huge. We use these capabilities all the time and the staff are incredibly helpful.”
With all of these capabilities, Sottos and her group are looking even further into autonomous materials—one day, she hopes to find the technology to not only repair, but regenerate new materials.
“Right now, things are good. Our group is growing, we have new grant support and many new ideas for autonomous materials,” Sottos said. “In the next five to 10 years I hope to be developing (in collaboration with Jeff and Scott) synthetic materials that are capable of regeneration (i.e., able to grow new material or remodel old material). I also hope to keep working on autonomous concepts to create more sustainable materials systems—materials capable of self-healing and self-reporting damage so they can have a longer life cycle.”
The success of Sottos and her group will continue to contribute to research in the field. “My goals are to maintain a great group of graduate students and continued success with my collaborators as long as we can. Not anything too lofty—just interesting science.”
This commitment to “interesting science,” coupled with her collaborative spirit, has made her a success not only at Beckman, but in her groundbreaking and promising research.