Continuous synthesis of tuneable sized silver nanoparticles via a tandem seed-mediated method in coiled flow inverter reactors

Abstract

Size control of metal nanoparticles is essential to achieve accurate adjustment of their unique chemical and physical properties. In this work, we present a novel approach for the continuous synthesis of silver nanoparticles with tuneable sizes between 5–10 nm and narrow size distribution (<20%) in the absence of steric capping ligands via a seed-mediated method. For this, two flow reactors are connected in series where rapid changes in the chemical environment enable the spatial and temporal separation of the nucleation and growth stages. A novel coiled flow inverter reactor configuration was developed to provide substantial cross sectional Dean mixing, substantially narrowing the residence time distribution under laminar flow. We also demonstrate that careful control of the nature of the reducing agents in each step is essential to avoid secondary nucleation and ensure narrow size distributions. This innovative new capability will not only provide fundamental understanding of the effect of the size of nanoparticles in a number of applications but also enable the deployment of large-scale well-defined nanoparticles for commercial uses.