(307f) Microchemical Reaction Engineering of Nanomaterials Syntheses

Khan, S. A., National University of Singapore

This talk will focus on the engineering of reactors for liquid-phase inorganic materials chemistry that enable production of nanomaterials with applications in diverse areas ranging from healthcare to energy capture and utilization. Despite significant advances in molecular understanding of materials in recent decades, synthetic methods in bottom-up materials chemistry have steadfastly adhered to ‘heating-and-beating’ in stirred flasks. The lack of structural specificity and control in such methods is not surprising when one compares the sizes of structures being synthesized (10 - 1000 nm) to the sizes of the ‘pots’ used for synthesis (0.1 - 1 m). The availability of more controlled, robust, and scalable nanoparticle manufacturing processes is thus crucial for the viability of emerging nanotechnologies. This need poses new and tantalizing problems for reaction engineers. Here I will present an overview of the challenges and opportunities in engineering microreactor systems for nanomaterials syntheses. Metallic or metal-based nanomaterials are particularly interesting due to their fascinating, broadly tunable optical (plasmonic) properties. These materials are typically prepared by rapid chemical reduction of metal precursors in aqueous solution, in the presence of atomic and molecular additives. Reagent mixing, chemical reaction(s) and nanoparticle nucleation and growth often occur in parallel, and such syntheses pose significant control, reproducibility and scale-up challenges in conventional batch reactors. I will describe how the benefits of tailored reagent contacting, structured reaction microenvironments, rapid mixing and accelerated inter-phase mass transport in multiphase microreactors can be harnessed to develop several unique process concepts with potential for scale-up to meet industrial needs.