Assessing the interactions that govern nanocrystal dispersion and assembly

With the support of the Macromolecular, Supramolecular and Nanochemistry Program of the Division of Chemistry, Prof. Milliron and Prof. Truskett at the University of Michigan seek to develop a fundamental understanding of the forces that keep nanoscale particles of metal oxides (nanocrystals) suspended as soluble inks or can lead to their precipitation. The results will be relevant for the understanding how nanocrystals can be effectively integrated in electronic or optical devices, and the concepts can be extended to help rationalize biomolecular interactions. Researchers participating in this project will receive training in computation and analytical techniques. A related symposium and webinar series will be organized, with a corresponding podcast to share knowledge across the scientific community and with a broader public audience. Since nanocrystal interactions are challenging to measure directly, the team will combine information from small angle X-ray scattering measurements, optical spectroscopy, and simulations to develop and validate models. The team will apply this strategy to analyze attractive and repulsive interactions between nanocrystals as they depend on experimentally accessible parameters like the concentration of added polymers and salts, pH, and solvent dielectric constant. Each of these parameters will be explicitly included in the models for interaction potentials, and the predicted trends in how they influence the nanocrystal dispersions will be quantitatively compared to the experiments. Further, the team will apply a recently developed simulation method to predict trends in the plasmonic optical spectra of the nanocrystal ensembles, providing additional validation of the interaction potentials inferred from small angle X-ray scattering. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.