ChEMS Seminar: Building “Ideal Polycrystals” From the Bottom-Up

Abstract: The densification of colloidal nanocrystal assemblies (CNAs) could bypass fundamental challenges that limit our control over the nanostructure and, therefore, the properties of materials. The removal of the ligands and the cracking that follows it are critical hurdles that stymied this approach. I will discuss on a plasma-processing approach to remove ligands down to 0.6 at% and our findings regarding how the structure of the CNA (i.e., the arrangement of the nanoparticles in the array) can completely suppress the formation of cracks due to volume loss over a wide range of film thicknesses. The process is demonstrated with particles of different composition, ligands, size, and shape, as well as with binary systems. Furthermore, I will show how the mechanical properties of these films can be quantitatively described by a granular model that accounts for particle size, packing fraction, surface energy, and bulk modulus.

Biography: Ludovico Cademartiri obtained a Laurea degree in materials science from the University of Parma in 2002 and a Ph.D. in chemistry from the University of Toronto in 2008. He was a NSERC Postdoctoral Fellow in the group of George M. Whitesides at Harvard University. His work spans materials chemistry, physical chemistry, molecular electronics, flame manipulation, plasma processing, polymers, and environments-by-design and has been recognized by national and international awards, most recently the Beckman Young Investigator Award and the Plant Science Institute Faculty Fellow Award. He has taught at Iowa State since 2012 where he leads a group of 16 students and postdocs.