Intelligentsia of Nano-Architected Hierarchical Materials
Julia R. Greer
Materials Science, Mechanics, Medical Engineering
California Institute of Technology
ABSTRACT
Creation of reconfigurable and multi-functional materials can be achieved by incorporating architecture into material design. Greer and her team design and fabricate three-dimensional (3D) nano-architected materials that can exhibit superior and often tunable thermal, photonic, electrochemical, biochemical, and mechanical properties at extremely low mass densities (lighter than aerogels), which renders them useful and enabling in technological applications. Dominant properties of such meta-materials are driven by their multi-scale hierarchy: from characteristic material microstructure (atoms) to individual constituents (nanometers) to structural components (microns) to overall architectures (millimeters and above).
Their research is focused on the fabrication, synthesis, and characterization of hierarchical materials using additive manufacturing (AM) techniques, and on investigating their mechanical, biochemical, electrochemical, and chemo-mechanical properties as a function of architecture, constituent materials, and microstructural detail. AM represents a set of processes that fabricate complex 3D structures using a layer-by-layer approach, with some advanced methods attaining nanometer resolution and the creation of unique, multifunctional materials and shapes derived from a photoinitiation-based polymerization of custom-synthesized resins and thermal post-processing. A type of AM, vat polymerization, has allowed for using hydrogels as precursors to produce 3D nano- and micro-architected metals and metal oxides, and exploiting their nano-induced material properties. They describe additive manufacturing via vat polymerization and function-containing chemical synthesis to create 3D nano- and micro-architected metals, ceramics, multifunctional metal oxides (nano- photonics, photocatalytic, piezoelectric, etc.), and metal-containing polymer complexes, etc., and demonstrate their potential in some biomedical, protective, and sensing applications. Greer describes how the choice of architecture and material can elicit stimulus-responsive, reconfigurable, and multifunctional responses.
SPEAKER
Greer obtained her S.B. in Chemical Engineering with a minor in Advanced Music Performance from MIT in 1997 and a Ph.D. in Materials Science from Stanford, worked at Intel (2000-03) and was a post-doc at PARC (2005-07). Greer joined Caltech in 2007 and currently is a Ruben F. and Donna Mettler Professor of Materials Science, Mechanics, and Medical Engineering at Caltech. She is also the Fletcher Foundation Director of the Kavli Nanoscience Institute and the Editor in Chief of the Journal of Applied Physics. She recently received the Nadai Medal from ASME Materials Division (2024), the Eringen Medal from the Society of Engineering Science (2024), won the inaugural AAAFM-Heeger Award (2019), was named a Vannevar-Bush Faculty Fellow by the US Department of Defense (2016), and was CNN’s 20/20 Visionary (2016). Her work was recognized among the Top-10 Breakthrough Technologies by MIT’s Technology Review (2015). Greer was named as one of “100 Most Creative People” by Fast Company and a Young Global Leader by World Economic Forum (2014). She has received multiple career awards: Kavli (2014), Nano Letters, SES, and TMS (2013); NASA, ASME (2012), Popular Mechanics Breakthrough Award (2012), DOE (2011), DARPA (2009), and Technology Review’s TR-35, (2008). Greer is also a concert pianist who performs solo recitals and in chamber groups, with notable performances of “Prejudice and Prodigy” with the Caltech Trio (2019), “Nanomechanics Rap” with orchestra MUSE/IQUE (2009), and as a soloist of Brahms Concerto No. 2 with Redwood Symphony (2006).