Nanocrystal Syntheses for Uniform Dispersion in Polar Media

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professors Smith and Schleife of the University of Illinois Urbana-Champaign are studying a new approach to manufacturing nanocrystals. Nanocrystals are an important part of the next generation of electronics, visual displays, solar cells, and medical tests. However, they are expensive because they require new manufacturing procedures that are not yet scalable, and their production generates new types of waste products that are difficult to process. The new approach is based on “alkoxy reactions” which replace oil-based liquids used in traditional nanocrystal reactions with liquids that are more similar to water. As a result, methods can be used that have already been industrially scaled and do not generate complex waste products. The new approach can also be performed safely and at low cost in classrooms and educational labs. The project will focus on understanding alkoxy reactions, including how the nanocrystal attaches to molecules within the reactions that cause the products to have long-term stability, how the liquids influence the quality of the products at high reaction temperatures, and how the nanocrystal products can be joined to biological molecules for use in medical applications. Both experimental and theoretical approaches will occur in tandem in order to reach both a fundamental and applied understanding of alkoxy reactions. With success of the project, it is expected that low-cost nanocrystals will become more readily available for advanced devices and medical tests. With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professors Smith and Schleife of the University of Illinois Urbana-Champaign are studying a new synthetic method for diverse classes of nanocrystals. Current compound nanocrystals are normally synthesized in nonpolar alkane-based solvents with high boiling points but they require extensive processing for applications in polar solvents such as water. In a new approach, nonpolar solvents will be replaced with ones that are polar to enable immediate dispersion in both nonpolar and polar solvents including water. The primary focus is on the use of solvents and reagents with alkoxy functional groups such as ethers, esters, and alcohols. The project aims to understand (1) how ligands in these reactions bind to the nanocrystal surface to elicit long-term stability, (2) how solvent properties (dielectric constant and reactivity) determine the colloidal stability of the nanocrystals at high temperatures needed for the production of high-quality products, and (3) how chemical reactions occur on terminal functional groups of the ligands to allow covalent conjugation to biomolecules. The reactions are expected to allow scalable manufacturing using minimal unit operations to generate colloidally stable products in polar solvents. The reactions are also expected to generate benign waste products due to processing and purification in aqueous solvents. With success of the project, low-cost and scalable manufacturing of diverse nanocrystals should be more accessible to non-experts and in educational settings. 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.