NER: Microfluidic-Enabled Synthesis of Nanoparticles and Hierarchical NanoClusters

Carnegie Mellon University, Pittsburgh PA

Investigators

Abstract

National Science Foundation - Active Nanostructure and Nanosystems (ANN) (NSF 05-610) Nanoscale Exploratory Research (NER) ABSTRACT Proposal Number: 0608864 Principal Investigator: Anna, Shelley Affiliation: Carnegie Mellon University NER: Microfluidic-Enabled Synthesis of Nanoparticles and Heirarchial NanoClusters This grant is to develop a new type of microfluidic-based technique for formation of metal and semiconductor nanoparticles. A novel, hierarchical and active manufacturing process in which highly monodisperse nanoparticles can be produced in a continuous and robust fashion will be developed. The method centers on recent microfluidic emulsification methods, but exploits the presence of surfactants at liquid-liquid interfaces to bring about the formation of droplets orders of magnitude smaller than the host device. Specifically, the tipstreaming phenomenon will be used to produce a continuous stream of submicron droplets. The reactant streams for nanoparticle synthesis will be encapsulated in the resulting submicron droplets, and will subsequently react to form highly monodisperse nanoparticles (1-10 nm) within the droplets. Two key advantages of using submicron droplets as nanoparticle reactors are that (1) submicron length scales allow for very effective diffusive mixing, minimizing the need for additional mixing schemes and enabling reaction kinetics to be isolated, and (2) resulting tiny reactor volumes lead to limited reactant supply within a single nanoreactor, allowing precise control over the number and size of nanoparticles formed. Furthermore, the ability to easily tune flow and reaction conditions inline in microfluidic devices leads to an inherently active nanoscale process. The fundamental knowledge gained from these studies will significantly contribute to a growing body of knowledge in the area of microreactor and nanoparticle technology. The results of this exploratory research will enable additional nanomanufacturing processes for synthesis of other novel nanostructures, including nano-alloys and nano-clusters controlled by the formation of concentric or sequential droplet reactors, high throughput screening devices for systematic, combinatorial study of nanoparticle chemistries, and the use of nanostructured hydrogels within submicron reactors to enhance nanoparticle uniformity while minimizing aggregation. The broader impacts of this work include the significant potential for the proposed method to realize wide application. In particular, a wide range of possible materials and chemistries can be utilized with this method, and a wide range of novel nanostructures can be synthesized. In addition, educational and outreach activities of the PI's will center on dispelling common misconceptions about nanotechnology, and will utilize the highly visual nature of microfluidics to appeal to audiences that are diverse in age, gender, and ethnicity.