Nancy Sottos is an American materials scientist and professor of engineering. She is the Swanlund Endowed Chair and the head of the department of materials science and engineering at the University of Illinois at Urbana–Champaign. She is also a co-chair of the Molecular and Electronic Nanostructures Research Theme at the Beckman Institute for Advanced Science and Technology. She heads the Sottos Research Group.
Sottos studies deformation and failure of materials at mesoscale, microscale, and nanoscale levels, and has made significant contributions in self-healing material, advanced polymer matrix composites, and thin films. She is a pioneer in the area of adaptive materials, creating the first self-healing polymers with Jeffrey S. Moore, Scott R. White, and others as of 2000.
Education
Nancy Sottos studied mechanical engineering at the University of Delaware, receiving her B.S. in 1986 and her Ph.D. in 1991. She also participated in women's varsity track and field and was active on the Athletic Governing Board and the Commission on the Status of Women.
Career
Sottos accepted a faculty position in the college of engineering at the University of Illinois at Urbana–Champaign in 1991. She was a member of the department of theoretical and applied mechanics, eventually serving as its interim head. In 2006 she joined the department of materials science and engineering. She was named the Donald B. Willet Professor of Engineering of the Department of Materials Science and Engineering and a University Scholar. She was appointed co-chair of the Molecular and Electronic Nanostructures Research Theme at the Beckman Institute for Advanced Science and Technology in 2004, succeeding Jeffrey Moore.
Sottos has been active on the editorial boards of Experimental Mechanics (1999–2006) and Composites Science and Technology (2002–present). She is a Fellow of the Society of Engineering Science (2007) and Fellow of the Society for Experimental Mechanics (2012). She was the president of the Society for Experimental Mechanics for 2014–2015. She was elected a member of the National Academy of Engineering in 2020 for contributions to the design and applications of self-healing and multifunctional materials.
Research
Self-healing polymers
Sottos helped develop the first polymeric self-healing material with colleagues including Jeffrey Moore and Scott White. The work was completed in 2000, and published in Nature in 2001. They have shown that microencapsulated healing agents can polymerize to heal areas of damage such as cracks smaller than a human hair. Their approach was to develop a polymeric matrix which involved both a reactive liquid healing agent and a catalyst. While undamaged, these were kept structurally separate. The liquid agent was contained inside non-reactive reservoirs within the material, while the catalyst was dispersed throughout the polymer. Once the material was damaged and a crack occurred, the reservoirs broke open, and capillary action caused the liquid agent to disperse into the damaged area, where it reacted with the catalyst and solidified to seal the crack. They have studied both the use of a contained healing agent and a dispersed catalyst, and the use of a dispersed healing agent and a contained catalyst. Using dicyclopentadiene (DCPD) and Grubbs' catalyst in an epoxy matrix, polycyclopendiene was formed to seal cracks, recovering up to 75% of the original fracture toughness.
They have since developed a catalyst-free self-healing system using chlorobenzene microcapsules for the active solvent. Cracking releases the chlorobenzene solvent, which washes pockets of unreacted epoxy monomers into the crack. There polymerization occurs to fill the crack. Tests of the catalyst-free self-healing system have restored up to 82% of the fracture’s strength.
Both approaches are examples of autonomous self-healing, in which the repair mechanism is triggered by the occurrence of damage. Materials that autonomously self-repair can retain their structural integrity under stress and last longer.
Microvascular networks
Sottos has also focused on the design of microvascular networks for the distribution of active fluids in autonomous materials systems. Such designs offer possibilities for "self-healing, regeneration, self-sensing, self-protection and self-cooling" properties, similar to those of biological systems.