Experimental and computational investigation of mixing dynamics in millifluidic jet mixing reactors

• Mixing in millifluidic jet reactors driven by vortices and secondary flows. • Experimental mixing times quantified using Villermaux-Dushman reactions as 2–140 ms. • CFD simulations can predict mixing times using mixing indices (0.95–0.98). • Nanoparticle synthesis shows a critical flow rate for size stabilization. • PLGA nanoparticles (∼300 nm) produced at industrially-relevant rate (∼1.3 kg/day). Rapid mixing is a critical step in many nanoparticle syntheses that can impact the ability to scale production from bench to industrial levels. This study combines experimental and computational approaches to characterize mixing dynamics in crossflow jet mixing reactors (JMRs) with millimeter-scale internal dimensions. The Villermaux-Dushman reaction system is used to quantify experimental mixing times across different reactor sizes and flow rates. Complementary computational fluid dynamics (CFD) simulations assess changes in the state of the flow and estimate mixing times under varying operating conditions. Mixing times derived from CFD results agree well with the experimental results for mixing indices between 0.95 and 0.98. To demonstrate the impact of mixing on nanoparticle formation, we synthesize polybutylacrylate- b -polyacrylic acid (PBA-PAA) block co-polymer nanoparticles, confirming the existence of a critical flow rate beyond which particle size stabilizes. Additionally, we produce polylactic acid-co-glycolic acid (PLGA) nanoparticles incorporating a hydrophobic dye, achieving an average particle size below 300 nm at a throughput of ∼ 1.3 kg/day. These results provide insights into optimizing JMRs for high-throughput, reproducible nanoparticle synthesis, bridging the gap between benchtop and industrial-scale production.