Investigating nucleation and growth phenomena in microfluidic supercritical antisolvent process by coupling in situ fluorescence spectroscopy and direct numerical simulation

High-pressure microfluidic systems exhibit favorable capacity to enhance mixing quality compared to conventional macroscale liquid systems. These mixing conditions are very interesting for the preparation of fluorescent organic nanoparticles by supercritical antisolvent process. In this work, fundamental mechanisms of microfluidic supercritical antisolvent process (mSAS) including thermodynamics, hydrodynamics, nucleation/growth phenomena, are investigated using a coupled experimental/simulation approach. Specifically, we determined experimentally the particle precipitation field in a CO2 / solvent medium using a fluorescent organic dye molecule which presents an enhancement of fluorescence intensity in its aggregated state (AIE effect). The results of the direct numerical simulation considering all the physical phenomena are compared with the experimental data for validation and deep understanding of the mechanisms. It is shown that despite ultra-short mixing time, the supersaturation field showed some fluctuation leading to variation of the nucleation times. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

High-pressure microfluidic systems have better mixing quality for preparing fluorescent organic nanoparticles compared to conventional liquid systems. This study investigates the fundamental mechanisms of microfluidic supercritical antisolvent process, including the particle precipitation field and nucleation times, using experimental and simulation approaches. Despite the ultra-short mixing time, fluctuations in the supersaturation field can lead to variations in nucleation times.