NanoParticle Self-Assembly at UofM

Theory and Practice synergize R&D

Sharon C. Glotzer and Nicholas A. Kotov are both researchers at the University of Michigan who were just awarded a MRS Medal at the Materials Research Society (MRS) Fall Meeting in San Francisco for their work on “Integration of Computation and Experiment for Discovery and Design of Nanoparticle Self-Assembly.” Due to the fact that surface atoms compose a large percent of the mass of nanoparticles, the functional properties of quasi-1D nanoparticles differ significantly from 2D thin-films and from 3D bulk materials. An example of such a unique functional property is seen in self-assembly of nanoparticles to form complex structures, which could find applications in renewable energy production, optoelectronics, and medical electronics.
While self-assembly has been understood as an emergent property of nanoparticles, research and development (R&D) has been somewhat limited to experimental trial-and-error due to a lack of theory. Glotzer and Kotov along with their colleagues have moved past this limit using a tight collaboration between computational prediction and experimental observation. The computational theorist Glotzer provides modeling on shapes and symmetric structures, while the experimentalist Kotov’s explores areas involving atomic composition and finite interactions. Kotov and his students create a nanoparticle and look for Glotzer and her group to explan the structure. Conversely, Glotzer predicts the formation of certain structures and has those predictions confirmed experimentally by Kotov.
One specific area the two scientists have explored is the formation of supraparticles—agglomerations of tightly packed nanoparticles that are self-limiting in size. The supraparticles are so regular in size and sphericality that they would actually pack to form face-centered-cubic (fcc) lattice-like structures. The theoretical and computational work, followed by experimental verification, further proved that these supraparticles could be formed from a vast variety of nanoparticles and even proteins, provided they were small enough and had significant van der Waals and electronic repulsion forces. This exciting development creates a whole new class of “bionic” materials that may combine biomaterials and inorganics.
—E.K.