The deadline for symposium submissions for the 2017 Mach Conference has been extended to…
Prof. Nancy Sottos
Department of Materials Science and Engineering
Beckman Institute for Advanced Science and Technology
University of Illinois at Urbana-Champaign
Mechanochemically Active Soft Composites for Shockwave Energy Dissipation
Inspired by mechanotransduction in biological systems, an emerging class of stimuli-responsive polymers responds chemically to mechanical forces. Mechanochemical degradation of polymer chains has been widely studied, but more recent investigations have focused on the productive channeling of mechanical energy to activate chemical pathways that favorably alter or enhance the properties of the polymer. Successful strategies for the development of mechanochemically active polymers include force-induced aggregation of molecules, supramolecular re-organization of chain segments, distortion of crystalline colloidal arrays, swelling/deswelling reactions, and activation of force-sensitive molecules, i.e., mechanophores, linked into the polymer backbone. Here, we examine the potential of mechanochemical reactions in materials for dissipation of shock wave energy. We have developed a series of network-forming ionic liquids (NILs) that possess intriguing absorption properties upon laser-induced shockwave loading. Microstructure analysis by X-ray scattering suggests nano-segregation of alkyl side chains and charged head groups in NILs. Further post-shock observations indicate changes in the low Q region implying that the soft alkyl domain plays an important role in absorbing shockwaves. To better harness the promising energy dissipation properties of NILs, we have created phase-separated soft silicone composites containing micron size ionic liquid droplets. These soft composites possess unique mechanical and dissipative properties and provide and interesting platform for the design of mechanochemically active materials that mitigate damage.
Bio: Nancy Sottos is the Donald B. Willet Professor of Engineering in the Department of Materials Science and Engineering at the University of Illinois 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 and a University Scholar. Sottos started her faculty career at Illinois after earning a B.S. and a Ph.D. in 1986 and 1991, respectively, in mechanical engineering from the University of Delaware. Her research focuses on the development of autonomic materials systems that have the ability to achieve adaptation and response in an independent and automatic fashion. Recent highlights of Sottos’ work include: (i) nanostructured self-healing polymers, (ii) self-sensing, mechanochemically active polymeric materials, (iii) autonomous materials systems with microvascular networks, (iv) fluorescent digital image correlation strain measurement with nanoscale resolution, and (v) metrology for dynamic interfacial adhesion measurement in multilayer thin films.