Megalibraries: Tools for exploring and expanding the materials genome

Throughout history, the materials we have used and relied on have evolved over time, slowly becoming more and more complex. The progression from the stone tools used by early-man to the composite synthetic materials used today took centuries due to the massive parameter space that materials encompass. For instance, when one considers the 91 metal elements in the periodic table, and all possible combinations of them, a nearly infinite number of possible materials exist. This is particularly true at the nanoscale where small changes in size or shape, even at a fixed chemical composition, can dramatically change a material’s properties. Therefore, the ability to rapidly synthesize and subsequently screen materials for desired properties is needed. We have developed a cantilever-free scanning probe lithography-based approach that, through the deposition of polymeric nanoreactors and thermal annealing, enables the preparation of “megalibraries” of as many as 5 billion positionally encoded nanoparticles and opens the new field of combinatorial nanoscience. The libraries can be tailored to encompass a wide variety of alloy and phase-separated nanoparticles that are comprised of as many as 8 different elements with up to four phases and six interfaces. Importantly, one megalibrary contains more new inorganic materials than chemists cumulatively have produced and characterized to date and can be used to identify new materials and catalysts for important chemical transformations. In addition, from these libraries, important insight into how thermodynamic phases form in polyelemental nanoparticles has been obtained, and design rules for engineering heterostructures in a polyelemental nanoparticle have been established. Therefore, this novel approach lays the foundation for creating an inflection point in the pace at which we both explore the breadth and discover the capabilities of the materials genome.