סמינר זיידמן

Materials by Design:

Three-Dimensional (3D) Nano-Architected Meta-Materials. Part I

Julia R. Greer

Departments of Materials Science, Mechanics, and Medical Engineering

California Institute of Technology, Pasadena, CA

http://www.jrgreer.caltech.edu

Creation of extremely strong and simultaneously ultra lightweight materials can be achieved by incorporating architecture into material design. In our research, we design and fabricate three-dimensional (3D) nano-architected materials that can exhibit superior and often tunable thermal, photonic, electrochemical, and ­mechanical pro­­­per­­ties at ex­tre­me­ly low mass densities (lighter than aerogels), which renders them useful, and often enabling, in many scientific pursuits and tech­no­lo­gi­cal applications. Dominant properties of such meta-materials are driven by their multi-scale nature: from characteristic material microstructure (atoms) to individual constituents (nanometers) to structural components (microns) to overall architectures (millimeters and above). 

To harness the beneficial properties of 3D nano-architected meta-materials, it is critical to assess their properties at each relevant scale while capturing over­all structural complexity. Our research is focused on fabrication and synthesis of such architected materials using 3D lithography, nanofabrication, and additive manufacturing (AM) techniques, as well as on investigating their mechanical, biochemical, electrochemical, electromechanical, and thermal properties as a function of architecture, constituent materials, and microstructural detail. We strive to uncover the synergy between the internal atomic-level microstructure and the nano-sized external dimensionality, where competing material- and structure-induced size effects drive overall response and govern these properties.

In Part I of the Seidman Lectures, I will focus on the mechanics of 3D nano-architected materials, which include compression, tension, and fracture experiments and simulations, as well as quasi-static vs. dynamic loading for a broad range of materials. I will describe an example where unusual mechanical properties of these nano-architected materials enable creating stimulus-responsive reconfigurable materials through electrochemistry.

Some relevant publications:

1. D. Yee, M. Lifson, J.R. Greer, Additive manufacturing of 3D architected multifunctional metal oxides, Adv. Mater. (2019) in press, DOI: 10.1002/adma.201901345.
2. X. Zhang et al, Lightweight, flaw-tolerant, and ultrastrong nanoarchitected carbon. PNAS, 116(14) (2019) 6665-72.
3. X. Xia et al., Electrochemically reconfigurable architected materials, Nature, 573 (2019) 205-13.
4. A.J. Mateos et al., Discrete‐continuum duality of architected materials: Failure, flaws, and fracture, Adv. Funct Mater., 29 (2019) article 1806772.
5. L.A. Shaw et al., Computationally efficient design of directionally compliant metamaterials, Nature Commun., 10 (2019) article 291.
6. A. Vyatskikh et al., Additive manufacturing of 3D nano-architected metals, Nature Commun., 9 (2018) article 593.
7. V. Chernow et al., Polymer nanolattices as mechanically tunable 3-dimensional photonic crystals, Appl. Phys. Lett., 107 (2015) article 101905.
8. L.R. Meza, S. Das, J.R. Greer, Strong, lightweight and recoverable three-dimensional ceramic nanolattices, Science,  345 (2014) 1322-6.