Nancy Sottos

Nancy Sottos is an American materials scientist and professor of engineering. She is the Donald B. Willet Professor of Engineering and the Head of the Department of Materials Science and Engineering at the University of Illinois at Urbana–Champaign.[2] She is also a co-chair of the Molecular and Electronic Nanostructures Research Theme at the Beckman Institute for Advanced Science and Technology.[3] She heads the Sottos Research Group.[4]

Nancy Sottos
Alma materUniversity of Delaware
Spouse(s)Scott White
Scientific career
FieldsMaterials science and engineering, molecular and electronic nanostructures
InstitutionsUniversity of Illinois at Urbana–Champaign
Doctoral advisorRoy McCullough[1]
External video
Nancy Sottos,“BP-ICAM Webinar Series 2016: Polymers with Biologically-Inspired Autonomous Functions”, The BP International Centre for Advanced Materials

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.[5] 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.[6][7][8]

Education

Nancy Sottos studied mechanical engineering at the University of Delaware, receiving her B.S. in 1986 and her Ph.D. in 1991.[3] 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.[1]

Career

Sottos accepted a faculty position in the College of Engineering at the University of Illinois at Urbana–Champaign in 1991.[2] 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.[9] She was named the Donald B. Willet Professor of Engineering of the Department of Materials Science and Engineering[2] and a University Scholar.[10] 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.[11]

Sottos has been active on the editorial boards of Experimental Mechanics (1999–2006) and Composites Science and Technology (2002–present).[3] She is a Fellow of the Society of Engineering Science (2007)[12] and the Society for Experimental Mechanics (2012).[13] She was the president of the Society for Experimental Mechanics for 2014–2015.[14][15] She was elected to the National Academy of Engineering in 2020.[16]

Research

Self-healing polymers

Sottos helped developed the first polymeric self-healing material with colleagues including Jeffrey Moore and Scott White.[7]:3–4[6] The work was completed in 2000, and published in Nature in 2001.[8] They have shown that microencapsulated healing agents can polymerize to heal areas of damage such as cracks smaller than a human hair.[11][17] 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.[7]

They have since developed a catalyst-free self-healing system[7] 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.[18]

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.[18][19]

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.[20]

To create such a material, a three-dimensional pattern of organic inks is laid down, and the interstitial pores in the pattern are filled with epoxy resin. The polymer is left to cure, and then the ink is removed. The spaces it leaves form well-defined, three-dimensional microchannel networks, which can be filled with healing agents. With this design, a greater supply of self-healing agent can be incorporated into the created material. The process of constructing such a material is very complex.[7]:8 This approach has been used to support repeated self-healing in fiber-reinforced composite materials. An epoxy resin and a hardener can be stored in adjacent overlapping microchannel networks. Damage to the network structure causes the healing agents to autonomously mix and polymerize, effectively glueing together the damaged area. Healing was reported to occur at nearly 100 percent efficiency over multiple fracture cycles. This approach has potential applications in the design and use of fiberglass and other composite materials for structures including airplanes and wind turbines.[21][22] It is reported that microvascular networks can support healing of larger-scale damage, up to 11.2 mm.[23]

Self reporting materials

A team led by Sottos and Wenle Li[24] has developed polymeric structural materials that can indicate the presence of damage by changing color. Such self-reporting materials can act as a color changing warning system.[25] The researchers created a polymer that contained microcapsules of epoxy resin and PH-sensitive dye. Damage to the polymer causes the capsules to break open and the epoxy and dye to mix. The resulting reaction causes the color of the material to change from yellow to red. The deeper the damage, the more intense the color change. This autonomous visual indicator can enable engineers to detect mechanical damage and intervene before a structure is compromised.[26][27]

Smart materials

Sottos is involved in the development of self-sensing, mechano- and thermo- chemically active polymeric materials. These smart inorganic polymers belong to the class of smart materials, exhibiting stimuli-responsive functions. A specific input stimulus such as a change in force or temperature can trigger a desired change in one or more properties of the polymer.[28][29]

Sensitivity to mechanical force

Mechanical force can provide a source of energy used by a desired chemical reaction.[30] To create such materials, mechanically sensitive chemical groups called mechanophores are built into the chemical structure of the polymer.[28] In one set of experiments, researchers used spiropyran molecules to detect mechanical stress. The spiropyran (SP) mechanophore was covalently bonded into a stretchy barbell-shaped polymer called polymethyl acrylate (PMA) and a small, glasslike bead-shaped polymer called polymethyl methacrylate (PMMA).[30] SP transformed into a fluorescent merocyanine (MC) form in response to stress. The orientation of the MC subspecies relative to the tensile force could be characterized based on the anisotropy of the fluorescence polarization. Spiropyrans were normally colorless but turned vivid shades of red or purple when stressed.[28] They also fluoresce.[30][31] The researchers have also demonstrated that mechanical force can power a chemical response in the polymer, changing the covalent bonding.[30] A next step in this research is to explore the potential to use mechanochemical reactions to activate chemical pathways in materials to respond to shock waves in positive ways, by altering or enhancing properties of the material.[32]

Thermal sensitivity

Another area of research focuses on the prevention of thermal runaway in batteries. The researchers coated the anode or separator layer of the battery with microspheres sensitive to heat. An increase in temperature causes the microspheres to melt, blocking transmission of the lithium ions and causing the battery to shut down. Microspheres of both polyethylene and paraffin wax were tested with CR2032 Li-ion batteries and demonstrated both successful operation of the battery at normal temperatures and shutdown of the battery at temperatures below those at which the battery's separator would become damaged.[29]

Thin films

Sottos has also been involved in research on thin films, and the measurement techniques for dynamic interfacial energy measurements of adhesion in multilayer thin films.[33][34]

Awards

Sottos has received numerous awards for her teaching and research. These include:[2]

  • The University of Delaware Presidential Citation for Outstanding Achievement (2002)[1]
  • The Hetényi Award from the Society for Experimental Mechanics (2004) for J. Wang, R. L. Weaver, N. R. Sottos “A parametric study of laser induced thin film spallation” Experimental Mechanics 42, no. 1 (2002): 74–83.[35]
  • The Hetényi Award from the Society for Experimental Mechanics (2016) for E.M.C. Jones, M.N. Silberstein, S.R. White, N.R. Sottos “In Situ Measurements of Strains in Composite Battery Electrodes during Electrochemical Cycling” Experimental Mechanics 54, no. 6 (2014): 971–985.[35]
  • Scientific American's SciAm 50 Award (2008)[36][37]
  • The M.M. Frocht[38] and B.J. Lazan awards from the Society for Experimental Mechanics (2011)[39]
  • Tau Beta Pi Daniel C. Drucker Eminent Faculty Award (2014)[40]

Culture

Self-healing materials created by Sottos and others at the Beckman Institute were included in the exhibit Science Storms at the Museum of Science and Industry in Chicago in 2010.[41]

References
  1. "12 UD alums honored with Presidential Citations". H O M e W O R D News from the Alumni Association. 11 (3). 2002. Retrieved 16 November 2016.
  2. "Nancy Sottos". International Center for Advanced Materials. Retrieved 13 November 2016.
  3. "Nancy R Sottos". MATSE: Materials Science and Engineering at Illinois. Retrieved 13 November 2016.
  4. "Sottos Research Group". Beckman Institute for Advanced Science and Technology at Illinois. Archived from the original on 2016-12-28. Retrieved 13 November 2016.
  5. "Trends in Advanced Materials R&D" (PDF). NL Agency Ministry of Economic Affairs. Dec 12, 2012. p. 25.
  6. Woodford, Chris. "Self-healing materials". ExplainThatStuff. March 15, 2016. Retrieved 13 November 2016.
  7. Ghosh, Swapan Kumar (2008). Self-healing materials : fundamentals, design Strategies, and applications (1st ed.). Weinheim: Wiley – VCH. pp. 3–4. ISBN 978-3-527-31829-2.
  8. White, S. R.; Sottos, N. R.; Geubelle, P. H.; Moore, J. S.; Kessler, M. R.; Sriram, S. R.; Brown, E. N.; Viswanathan, S. (15 February 2001). "Autonomic healing of polymer composites". Nature. 409 (6822): 794–797. Bibcode:2001Natur.409..794S. doi:10.1038/35057232. PMID 11236987. S2CID 11334883. The paper was submitted in 2000; the paper was published in 2001.
  9. "From the Head / Nancy Sottos joins MatSE Department". MASE at Illinois: MatSE Alumni News/. Winter: 3, 14. 2006.
  10. "Six University Scholars named at Urbana". Inside Illinois. 22 (14). February 20, 2003. Retrieved 16 November 2016.
  11. McGaughey, Steve (October 17, 2007). "Team Approach Pays Off Big for Moore". Beckman Institute. University of Illinois. Retrieved 10 June 2016.
  12. "Nancy Sottos to be named SES Fellow" (PDF). Synergy. Fall (3): 9. 2006. Retrieved 15 November 2016.
  13. "SEM Fellow". The Society for Experimental Mechanics. Archived from the original on 29 December 2016. Retrieved 15 November 2016.
  14. "Message from the President" (PDF). Experimentally Speaking. 5 (2): 1–2. 2014. Archived from the original (PDF) on 2016-12-29.
  15. "Executive Board 2016–2017". Society for Experimental Mechanics. Archived from the original on 29 December 2016. Retrieved 14 November 2016.
  16. "Dr. Nancy R. Sottos". NAE Website. Retrieved 2020-06-02.
  17. Toohey, Kathleen S.; Sottos, Nancy R.; Lewis, Jennifer A.; Moore, Jeffrey S.; White, Scott R. (10 June 2007). "Self-healing materials with microvascular networks". Nature Materials. 6 (8): 581–585. doi:10.1038/nmat1934. PMID 17558429.
  18. "Catalyst-free Chemistry Makes Self-healing Materials More Practical". Science Daily. December 3, 2007.
  19. Yuan, Y. C.; Yin, T.; Rong, M. Z.; Zhang, M. Q. (2008). "Self healing in polymers and polymer composites. Concepts, realization and outlook: A review". Express Polymer Letters. 2 (4): 238–250. doi:10.3144/expresspolymlett.2008.29.
  20. "Materials Research Lecture". Caltech. September 30, 2015. Archived from the original on 28 December 2016. Retrieved 14 November 2016.
  21. "Repeated Self-Healing Now Possible in Composite Materials". Beckman Institute. April 15, 2014. Retrieved 15 November 2016.
  22. Patrick, Jason F.; Hart, Kevin R.; Krull, Brett P.; Diesendruck, Charles E.; Moore, Jeffrey S.; White, Scott R.; Sottos, Nancy R. (July 2014). "Continuous Self-Healing Life Cycle in Vascularized Structural Composites". Advanced Materials. 26 (25): 4302–4308. doi:10.1002/adma.201400248. PMID 24729175.
  23. Krull, Brett P.; Gergely, Ryan C. R.; Santa Cruz, Windy A.; Fedonina, Yelizaveta I.; Patrick, Jason F.; White, Scott R.; Sottos, Nancy R. (July 2016). "Strategies for Volumetric Recovery of Large Scale Damage in Polymers". Advanced Functional Materials. 26 (25): 4561–4569. doi:10.1002/adfm.201600486.
  24. "Nancy Sottos and Wenle Li, University of Illinois at Urbana-Champaign (image)". EurekaAlert. Retrieved 16 November 2016.
  25. Robb, Maxwell J.; Li, Wenle; Gergely, Ryan C. R.; Matthews, Christopher C.; White, Scott R.; Sottos, Nancy R.; Moore, Jeffrey S. (28 September 2016). "A Robust Damage-Reporting Strategy for Polymeric Materials Enabled by Aggregation-Induced Emission". ACS Central Science. 2 (9): 598–603. doi:10.1021/acscentsci.6b00198. PMC 5043436. PMID 27725956.
  26. Lee, Rhodi (18 January 2016). "Color Changing Warning System May Prevent Costly Material Damage And Repair". Tech Times. Retrieved 16 November 2016.
  27. Li, Wenle; Matthews, Christopher C.; Yang, Ke; Odarczenko, Michael T.; White, Scott R.; Sottos, Nancy R. (March 2016). "Autonomous Indication of Mechanical Damage in Polymeric Coatings". Advanced Materials. 28 (11): 2189–2194. doi:10.1002/adma.201505214. PMID 26754020.
  28. Kloeppel, James E. (May 6, 2009). "See the force: Mechanical stress leads to self-sensing in solid polymers". Illinois News Bureau. Retrieved 8 December 2016.
  29. Glynn, Patrick (December 5, 2012). "Preventing Laptop Fires and "Thermal Runaway"". U. S. Department of Energy.
  30. Saunders, Fenella (2009). "Working Best Under Pressure". American Scientist. 97 (4): 291. doi:10.1511/2009.79.291. Archived from the original on 20 December 2016. Retrieved 8 December 2016.
  31. Beiermann, Brett A.; Kramer, Sharlotte L.B.; Moore, Jeffrey S.; White, Scott R.; Sottos, Nancy R. (17 January 2012). "Role of Mechanophore Orientation in Mechanochemical Reactions". ACS Macro Letters. 1 (1): 163–166. doi:10.1021/mz2000847. Archived from the original on 2016-12-20. Retrieved 16 November 2016.
  32. "Nancy Sottos". 2017 Mach Conference. Archived from the original on 21 December 2016. Retrieved 8 December 2016.
  33. Gunda, Manideep; Kumar, Pankaj; Katiyar, Monica (11 August 2016). "Review of Mechanical Characterization Techniques for Thin Films Used in Flexible Electronics". Critical Reviews in Solid State and Materials Sciences. 42 (2): 129–152. doi:10.1080/10408436.2016.1186006. S2CID 99385252.
  34. Tran, Phuong; Kandula, Soma S; Geubelle, Philippe H; Sottos, Nancy R (26 January 2011). "Comparison of dynamic and quasi-static measurements of thin film adhesion". Journal of Physics D: Applied Physics. 44 (3): 034006. Bibcode:2011JPhD...44c4006T. doi:10.1088/0022-3727/44/3/034006.
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  37. Lachance, Molly. "Researchers honored for work with self-healing plastics". Air Force Material Comman. Retrieved March 18, 2008.
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  39. "2011 SEM/IMAC Awards" (PDF). Experimentally Speaking. Retrieved 16 November 2016.
  40. "Outstanding Faculty To Be Honored April 28 at NCSA". College of Engineering. University of Illinois at Urbana-Champaign. Retrieved 16 November 2016.
  41. McGaughey, Steve (April 15, 2010). "AMS Group Contributes to Museum of Science and Industry Exhibit". Beckman Institute.
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