Model Reaction Systems to Produce Monodisperse Colloids

Abstract

Monodispersely-sized spherical metal oxide particles have recently attracted growing attention for many industrial applications. In particulate coating applications, controlling the size and distribution of the starting colloid plays a crucial role in the final coating properties (1,2). In chromatography, both porous and nonporous monodispersely sized colloidal particles have been used as a column-packing material (3,4). Monodisperse particles can also be used as a startingn material in a ceramic processing to make ceramic materials with uniform properties for mechanical, refractory, and catalysis applications.Even though various monodisperse metal oxide colloids are already widely used in industry, predicting and controlling the particle size distribution is frequently more dependent on experience and ingenuity rather than on modeling. There is nothing wrong with empiricism, but models can help to achieve process control, optimization, and flexibility. We have sought to assess what combination of processes in solution (both reactive and aggregative) need to be modeled, and in doing so we have found a number of very useful references that give insight into 1) the mechanism of the particle formation and growth, and 2) the effect of reaction parameters on the final size distribution by using both experimental and numerical techniques. Understanding these should allow us to intelligently design a new process in order to make particles with the desired size and distribution. In this short contribution we hope that it will be of service to provide a brief overview of some key work that may yield itself to modeling. This review is not intended to be comprehensive; instead, we have selected work that shows features that one hopes should be captured by meaningful models.