Nanoparticle precipitation in reverse microemulsions: particle formation dynamics and tailoring of particle size distributions

In this work, a detailed experimental analysis of the nanoparticle formation dynamics and the formation mechanism in a reverse microemulsion system is given. The precipitation of barium sulfate nanoparticles inside microemulsion droplets is investigated at the molecular scale with respect to the evolution of the particle size distribution and the particle morphology by an extensive transmission electron microscope (TEM) analysis. Different mixing procedures (feeding strategies) of two reactants, barium chloride and potassium sulfate, are evaluated concerning their ability for a tailored particle design under consideration of the complete particle size distribution (modality and polydispersity). It is shown that improved knowledge about the particle formation mechanisms, the dynamics, and the influence of the colloidal microemulsion structure could be used for a tailored design of particles,for example, controlled synthesis of nanoparticles with a bimodal particle size distribution by the application of a sophisticated feeding strategy.

Size and distribution prediction for nanoparticles produced by microemulsion precipitation: A Monte Carlo simulation study

A Monte Carlo simulation approach for BaSO(4) nanoparticle precipitation in microemulsions has been applied to a semi-batch reactor experiment. The simulation includes two technical process parameters, the feed rate and the initial volume ratio of the two reactants. A set of experiments with different initial reactant concentrations of BaCl(2) and K(2)SO(4) showed a significant change in the particle size. It was compared to the simulated final particle size and with an adaptation of one internal parameter of the Monte Carlo simulation a good agreement between simulated and experimental data was achieved. Using this set of parameters the feed rate and the initial volume ratio is varied. It is shown how these process parameters influence the particle size and the size distribution. The simulation results may help in finding appropriate control parameters in a scale-up approach of the microemulsion technology for nanoparticle production.