SUPERFON

Supercritical AntiSolvent (SAS) process is a key operation in powder technology, but one of the major issues is the poor understanding of the involved coupled phenomena, which directly control the nanomaterial characteristics. The objective of the SUPERFON project is to perform process screening and intensification by investigating SAS precipitation of model Fluorescent Organic Nanoparticles (FONs) thanks to complementary experimental/numerical approaches with advanced investigation tools like microfluidics coupled with in situ characterization and high performance computing. A complete description of the SAS process should be able to account for mass transfer related to the mixing of the species in the reactor, for hydrodynamics related to the injection of the solution, for phase equilibria related to the evolution of the solute solubility with the composition of the forming CO2-solvent mixture, and finally, for crystallization kinetics related to the nucleation of the solute and its growth as particles or crystals. Nowadays, one of the main challenges, in addition to the deep understanding of the process, remains to access and model the parameters of the growth rate or the nucleation parameters. This will be achieved through the comparison of the experimental variables of interest (velocity, concentration, particle size…) obtained by in situ techniques in the well-controlled microfluidic devices. Therefore, due to their special fluorescence properties, FONs based on Aggregation-Induced Emission-active molecules will be excellent models to get a thorough understanding of the SAS process. Indeed, AIE-active compounds have the rare property to emit light efficiently only in the solid state, thus enabling real-time monitoring of the nanoparticle formation. Conversely, the use of sustainable supercritical technologies should allow reducing and controlling the size of produced materials. Furthermore, to go through fundamental mechanisms to processes and to realize the promise of an efficient “green” process, it is essential to access large production scales. One major originality of the approach will be to propose the same level of description for the simulation in microfluidic device as in the larger reactor. Therefore, intensive simulation (High Performance Computing) will be used as a real tool of the process design (reactor, injector design, and operating conditions) to investigate two scaling options, i.e. scaling-up (large semi-continuous reactor) vs. numbering-up (parallel microfluidic reactors).