(70b) The Influence of Nucleation Kinetics on the Particle Population Dynamics in Microemulsion Precipitation Using Molecular Modelling Approaches

The production of particles with a well-defined size and a narrow size distribution is of great importance in a large number of industrial applications. Especially the production of particles at the nanoscale is a hot topic due to an increasing commercial interest in such materials. This process still represents a major technological challenge due to the complexity of the phenomena involved and corresponding fundamental research, both experimentally and theoretically, is necessary.

We have already experimentally shown that one viable alternative for the production of nanoparticles using liquid-based chemical reaction engineering is the a particle precipitation in microemulsions [1]. Here the droplets of the microemulsion are used as a nanoreactors filled with reactants. Due to a continuous fusion and fission of droplets and a corresponding exchange of the contents the whole process leads to controllable chemical reactions inside the droplets followed by nucleation and growth.

A fundamental understanding of the dynamics of the particle population in such a process is key to proper analysis and control. As this process includes a large number of variables one very useful tool of modelling and simulation is the Monte Carlo approach. The applicability of the approach to this particular process has been shown already in [2]. It has been seen that one of the keys in understanding particle precipitation is the nucleation phenomena and a more thorough investigation of this particular part of the process will help to gain a better fundamental understanding as well as an improved model for process analysis and design.

In this presentation we will show our investigations of the detailed kinetics of the nucleation phenomena using molecular modelling approaches. This will include the application of Gibbs-Thompson theory as well as the simulation of particle nucleation inside droplets by molecular dynamics simulation. This investigations will help to improve the model capabilities used to predict the global particle precipitation dynamics in microemulsions. A comparison to experiments on Barium Sulfate nanoparticle precipitation in a technical microemulsion of cyclohexane, Marlipal O13/40 and water will be helpful to find appropriate parametric descriptions of the nucleation phenomena in particle precipitation processes.

[1] D. Adityawarman, A. Voigt, P. Veit and K. Sundmacher: Precipitation of BaSO4 Nanoparticles in a Non-ionic Microemulsion: Identification of Suitable Control Parameters, Chemical Engineering Science 60, p.3371-3383 (2005).

[2] A. Voigt, D. Adityawarman and K. Sundmacher: Size and distribution prediction for nanoparticles produced by microemulsion precipitation: A Monte-Carlo simulation study, Nanotechnology 16, S429-S434 (2005).