Materials Science Research Lecture
Creation of extremely strong and simultaneously ultra lightweight materials can be achieved by incorporating architecture into material design. We fabricate 3-dimensional nano-architectures whose constituents vary in size from several nanometers to tens of microns to millimeters and centimeters, that exhibit superior thermal, photonic, electrochemical, and mechanical properties at extremely low mass densities (lighter than aerogels), rendering them ideal for many scientific and technological applications. The dominant properties of such meta-materials, where individual constituent size (atoms to nanometers to microns) is comparable to the characteristic microstructural length scale of the constituent solid, are largely unknown because of their multi-scale nature. To harness the beneficial properties of 3-dimensional nano-architected meta-materials, it is critical to assess properties at each relevant scale while capturing the overall structural complexity. We discuss the deformation, as well as mechanical, biochemical, electrochemical, and photonic properties of nanolattices made of different materials and with a range of different atomic-level microstructures. Attention is focused on the interplay between the internal critical microstructural length scale of materials and their external limitations in revealing the physical mechanisms that govern these properties, where competing material- and structure-induced size effects drive overall response. Specific discussion topics include: fabrication and characterization of (often hierarchical) 3-dimensional nano-architected meta-materials for applications in chemical and biological devices, ultra lightweight energy storage systems, damagetolerant fabrics, and photonic crystals.
Some Relevant publications:
1. L. R. Meza, S. Das, J. R. Greer "Strong, Lightweight and Recoverable Three-Dimensional Ceramic Nanolattices" Science 345, 1322-1326 (2014)
2. D.W. Yee, M.D. Schulz, R.H. Grubbs, & J.R. Greer "Functionalized 3D Architected Materials via Thiol-Michael Addition and Two-Photon Lithography" Advanced Materials doi: 10.1002/adma.201605293 (2017)
3. J.R. Greer "Materials by design: Using architecture and nanomaterial size effects to attain unexplored properties." Nat'l Acad. of Engineering's Bridge 45(4) (2015)
4. L. Meza, et al., J.R. Greer "Hierarchy in 3-D Architected Meta-Materials Brings Resilience" Proc of the Nat'l Academy of Sciences 112 (37), 11502 (2015)
5. X. Xia, C. V. Di Leo, X. W. Gu, A. Lozano, J. R. Greer "In Situ Lithiation–Delithiation of Mechanically Robust Cu–Si Core–Shell Nanolattices in a Scanning Electron Microscope" ACS Energy Letters 1, 492–499 (2016)
6. V. Chernow, H. Alaeian, J. Dionne, J.R. Greer ""Polymer Nanolattices as Mechanically Tunable 3-Dimensional Photonic Crystals" Appl. Phys. Lett 107,101905 (2015)
7. C. Xu, Z. Ahmad, A. Aryanfar, V. Viswanathan, & J.R. Greer "Enhanced strength and temperature dependence of mechanical properties of Li at small scales and its implications for Li metal anodes" Proc Nat'l Acad Sciences of the USA 114 (1), 57-61 (2016)
Greer's research focuses on creating and characterizing new classes of materials that utilize the combination of 3-dimensional architectures with nanoscale-induced material properties. These nano-architected meta-materials have multiple applications as biomedical devices, battery electrodes, and lightweight structural materials and provide a rich "playground" for fundamental science. Greer has S.B. in Chemical Engineering (minor in Advanced Music Performance) from MIT in 1997, Ph.D. in Materials Science from Stanford, worked at Intel (2000-03) and was a post-doc at PARC (2005-07). Julia joined Caltech in 2007 and currently is a full professor with appointments in Materials Science, Mechanical Engineering, and Medical Engineering. Greer has over 100 publications; she was recently named a Vannevar-Bush Faculty Fellow (2016) and CNN's 20/20 Visionary (2016), she was selected as a Midwest Mechanics lecturer (2015), and her work was recognized among Top 10 Breakthrough Technologies by MIT's Technology Review (2015). She was a Gilbreth Lecturer at the National Academy of Engineering (2015), is a Young Global Leader by World Economic Forum (2014) and is a recipient of multiple awards: Kavli Early Career (2014), Nano Letters Young Investigator Lectureship (2013), Society of Engineering Science Young Investigator (2013), TMS Early Career Faculty (2013), NASA Early Career Faculty (2012), Popular Mechanics Breakthrough Award (2012), ASME Early Career (2011), DOE Early Career (2011), TMS's Young Leaders (2010), DARPA's Young Faculty (2009), Technology Review's TR-35, (2008), and NSF's CAREER (2007). Greer serves as an Associated Editor of Nano Letters and on the Board of Reviewing Editors for Science. She is also a concert pianist, with recent performances of "nanomechanics rap" with MUSE/IQUE, solo piano recitals and chamber concerts (2007-present), and as a soloist of Brahms Concerto No. 2 with Redwood Symphony (2006).