NIRT: Understanding Robust Large Scale Manufacturing of Nanoparticles and Their Toxicology

Overview: While a myriad of options exist to manufacture so-called engineered nanoparticles, very few are industrially viable. Furthermore, no clear path exists to transition small-scale laboratory experiments to large-scale economically and environmentally viable processes. An additional concern is the unknown toxicological properties of engineered nanoparticles. To address the above issues, this project focuses on two thrust areas -- manufacturing process relationships and toxicological relationships - and involves an academic, government, industrial partnership, encompassing the disciplines of Chemistry, Chemical and Mechanical Engineering, and Medicine. University of Maryland: During the first year we have built, with partial support from the Cabot corp. a flame driven synthesis reactor. The reactor is designed to produce up to 100 g/hr of carbon and metal/carbon nanocomposite particles. The reactor is now operational and we have been generating particles. At the present time we are still dealing with some reactor instability issues. The reactor is now instrumented with an on-line scanning mobility particle sizing system so that real time size distribution measurements can be obtained. One of the motivations for this project was to generate new classes of carbon based nanostructures. To that end this year we have created what we call "Sea Urchin" like hybrid nanoparticle/nanotube structures (1). These materials have been shown to enhance the thermal conductivity of fluids by as much as 20% for only a 0.2% volume loading of particle (2). This year we have also developed a new approach to inject directly nanoparticles into solution thus preventing contamination/and agglomeration to corrupt the toxicological studies. The approach relies on condensing water vapor to each nanoparticle in free flight, thus growing each nanoparticle to a droplet of ~ 10um, so as to increase the momentum of the particle and enable efficient injection into solution. Future work will involve completing the last few modifications to the reactor and begin to collect data on the role of fuel structure and catalyst loading on the yield, size, and structure of nanoparticles. Form these results we will down-select materials that will be