LAUSR

The controlled and continuous production of nanoparticles with functionalized surfaces remains a technological challenge. We present a multistage synthetic platform, consisting of 3D-printed miniature continuous stirred-tank reactors (CSTRs), for the continuous synthesis and functionalization of SiO2 NPs. The use of the CSTR platform provides ideal and rapid mixing of precursor solutions, precise injection of additional reagents for multistep reactions, facile operation when using viscous solutions and handling of syntheses with longer reaction times. To exemplify the use of such custom-designed CSTR units, amine and carbohydrate-functionalized SiO2 NPs are chosen as model reaction systems. In particular, the intensified flow reactor units allowed for the reproducible formation of SiO2 NPs with diameters less than 100 nm and narrow size distributions (3 - 8%). Most importantly, by assembling various 3D-printed CSTR units we synthesized gluconolactone capped polyethylenimine-modified silica nanoparticles in a fully continuous manner. The inherent control over nanoparticle surface charge, reactor scalability and the significant shortening of processing times (less than 10 min) compared to batch methodologies (several days) strongly indicate the ability of the reactor technology to accelerate continuous nanomanufacturing. In general, it provides a simple route for the reproducible preparation of functionalized NPs, and thus, expanding the gamut of flow reactors for material synthesis.