NIRT: Environmentally Benign Deagglomeration and Mixing of Nanoparticles

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This award was received in response to Nanoscale Science and Engineering initiative, NSF 04-043, category NIRT. Nanoparticles and nanocomposites offer unique properties that arise from their small size, large surface area, and the interactions of phases at their interfaces, and are attractive for their potential to improve performance of drugs, biomaterials, catalysts and other high-value-added materials. However, a major problem in utilizing nanoparticles is that they often lose their high surface area due to grain growth or unavailability of the high surface area where it matters. Creating nanostrauctured composites where two or more nanosized constituents are intimately mixed can prevent this loss in surface area, but in order to obtain homogeneous mixing, de-agglomeration of the individual nanoparticle constituents is necessary. A supercritical fluid (SCF), such as supercritical carbon dioxide, which has liquid-like density and solubility, yet gas-like diffusivity and viscosity, and is environmentally friendly, is an ideal medium for the purpose of deagglomerating nanoparticles because it can penetrate the pores within the nano-agglomerates, and upon rapid depressurization, can cause fragmentation and separation of the nanoagglomerates from within. The use of a SCF for producing well-mixed nanocomposites has a number of advantages: no organic solvents or even water is required, the processing is done at near room temperature, high levels of compressive stresses or friction forces are avoided, and since liquids are not used the cost of drying and solvent removal is eliminated, and substance purity is preserved. A combination of experiments and multiscale simulations, at three different length scales, is necessary to obtain a fundamental scientific understanding of the deagglomeration and subsequent mixing processes. This award is aimed at developing such core knowledge that will advance the field of nano-materials.Due to a comprehensive education and training program that includes students from K-12 through postgraduate levels, the project will have broader impacts in terms of workforce development and public awareness of nanotechnology. The experimental and theoretical research will provide predictive capabilities that will help in optimization and scale-up, and subsequent technology transfer to industrial partners. Thus this work has the potential to evolve into major enabling technologies for producing nanocomposites in large quantities, and contribute to establishing a leadership position for the US in the nanomixing area. To carry out this multidisciplinary research and educational objectives, a highly talented team of researchers from four universities (NJIT, Rutgers, Princeton and Auburn) has been assembled. This team is committed to building upon their past successes in research and in integrating diversity through a multi-pronged effort on recruitment, mentoring, and retention of underrepresented minority and women students.