Nov 15, 2019
Brauer Hall, room 12
Dr. Sinan Keten, Associate Professor
Department of Mechanical Engineering
Hierarchical Design of Nanoparticle Assemblies Inspired from Biomechanical Functions
ABSTRACT: Biological materials excel at serving mechanical functions, which may be passive as in structural materials, or dynamic, as in cell motility and adhesion components. Impressively, structural biomaterials such as nacre, bone and wood defy “rule of mixtures” relationships by employing high aspect ratio nanoparticles as building blocks in clever molecular designs. Lack of understanding of the physics of interfaces within nanoparticle assemblies makes it challenging to achieve similar mechanical properties with man-made materials. In this talk, I will present and overview of the state of the art in the bottom-up analysis of nanoparticle assemblies, touching upon new advances in interface design enabled by molecular and multi-scale simulations, machine learning tools, as well as bioinspiration. As a case study, investigations on thin films and nanocomposites made from renewable cellulose nanocrystals (CNCs) will be presented. Our theory and simulation-based inquiries into three complementary strategies for improving mechanical properties will be discussed. First, I will present analyses that explain how binary mixtures of nanocrystal lengths, and microstructural features such as a twisted plywood (Bouligand) lay-up of nanocrystals yield all-cellulosic transparent films with strength and toughness comparable to mineralized biomaterials. Second, I will discuss an efficient, molecular simulation informed metamodeling framework for predicting the mechanical response of polymer grafted nanoparticle assemblies, revealing bioinspired interface designs that yield Pareto optimality between stiffness and toughness. Finally, I will conclude with an outlook on dynamic interfaces in nanocomposites, specifically examining how basic allosteric principles of catch bonds in proteins could be reduced to simple mechanical models to create nanoparticle linkages with counterintuitive force-dependent kinetics.
BIO: Sinan Keten is the June and Donald Brewer Associate Professor of Civil & Environmental Engineering and Mechanical Engineering at Northwestern University. He joined Northwestern University faculty in 2010 after obtaining his Ph.D. from MIT. His research expertise is on computational materials design and mechanics with an emphasis on soft matter, and has co-authored over a hundred journal articles in this area. Prof. Keten has received a number of honors including Presidential Early Career Award for Scientists and Engineers (PECASE), Office of Naval Research (ONR) Young Investigator Program (YIP) Award, Society of Engineering Science Young Investigator Medal, ASCE Huber Prize, ASME Sia Nemat Nasser Early Career Award, JMBBM Early Career Award, and the ASME Haythornthwaite Award. He is a Fellow of the American Physical Society.
Organizer / Host: Dr. Zhang