Fluid or Solid? The Physics of Shape-Shifting Materials

When we think of engineering materials, we often picture solid blocks such as steel or plastic with fixed properties—soft, lightweight, or strong. In contrast, granular materials such as sand or rice flow and shear. What if a material could do both? Polycatenated Architected Materials (PAMs) are a new class of structures that bridge the gap between solids and fluids. Made of interlocked particles forming intricate 3D networks—akin to modern-day chainmail—PAMs can switch from flowing like granular matter to behaving as solid elastic materials, depending on the applied forces. This unique duality defies conventional theories and enables applications ranging from safer sports gear, reconfigurable robotics, and smart devices for extreme environments. Join us to discover how the geometry and topology of PAMs are redefining what’s possible in material science and engineering.

Bio: Chiara Daraio is the G. Bradford Jones Professor of Mechanical Engineering and Applied Physics at Caltech. Her work is focused on developing new materials with advanced mechanical and sensing properties, for application in robotics, wearable devices, and vibration absorption. She received her undergraduate degree in Mechanical Engineering from the Marche Polytechnic University in Italy, and her M.S. and Ph.D. degrees in Materials Science and Engineering from the University of California, San Diego. She also works as a Research Scientist, Director, at Meta Reality Labs and previously served as the Chair of Mechanics and Materials at ETH Zürich, in Switzerland. Chiara received a Presidential Early Career Award (PECASE) from President Obama, a US Office of Naval Research Young Investigator Award, and a National Science Foundation CAREER award. She was elected as a Sloan Research Fellow and selected by Popular Science magazine among the “Brilliant 10." Her work has been highlighted by media outlets such as The New York Times and Scientific American, and she has appeared on television and radio programs, including CNN and PBS.