KEYNOTE: Combining fluidization and gas-phase coating: surface modification at the nanoscale

Nanostructured particles (e.g., core-shell nanoparticles or porous micro-particles containing nanoparticles) have high potential in applications such as catalysis and energy storage, but also in medicine and food. However, to come from product design incorporating nanostructuring to actually making such materials at relevant scales is not trivial. Gas-phase coating using techniques such as atomic layer deposition (ALD) can be used to provide the surface of a particle with either an ultrathin continuous coating or a decoration of nanoclusters. In this way, we can benefit from the wide range of chemistries developed over the years for ALD.

When carried out in a fluidized bed or a pneumatic transport reactor, gas-phase coating is an attractive way of producing nanostructured particles with excellent scale-up potential. Even nanopowders can be fluidized to be modified this way, although they are not present as individual particles but as very dilute agglomerates.

I will discuss how to fluidize (ultra-)fine powders in order to obtain a high coating quality. Also other requirements for this coating approach will be examined. I will demonstrate how it can be deployed to tune the wettability behaviour of particles, and how it can be used to give pharmaceutical powders controlled-release properties. Moreover, the application to catalysis will be discussed.