<87e> Manipulation and control of the particle size distribution of nanoparticles during their formation in microemulsion droplets by a suitable feed strategy

The properties of nanoparticles and the performance of products made with nano-sized precursors significantly depend on the shape of the particle size distribution (PSD) or more precisely the broadness of the PSD, the modality and of course the specific particle sizes covered by the PSD. Especially the controlled adjustment of particle size is of interest due to the size-dependent physical and chemical properties of nanoparticles below 100 nm [1]. The precipitation of particles inside the droplets of a microemulsion is a process, which allows the control of the particle size e. g. by the variation of initial concentrations of the reactants. Adityawarman et al. [2] showed that it is possible to precipitate narrowly distributed (variance: +/2-6 nm) barium sulfate nanoparticles in a range between 6 and 40 nm in a standard semi-batch operated stirred tank reactor by the microemulsion technique. Initially one reactant (potassium sulfate) was dissolved in the droplets inside the reactor with a certain concentration and the other reactant (barium chloride) was dissolved inside the feed droplets with a second concentration. The feeding time and the feed volume were kept constant for all these experiments. Feed strategies like a pulsed feed or a change of the feeding rate during the process, which could both have a significant influence on the resulting PSD, were not investigated so far.