On the Ripening of Solid Nanoparticles
Professor Ulf Olsson, Physical Chemistry, Lund University, Sweden
Info about event
iNANO Auditorium (1593-012), Gustav Wieds Vej 14, 8000 Aarhus C
On the Ripening of Solid Nanoparticles1
Ostwald ripening is a common coarsening mechanism for phases fragmented to small submicron dimensions. Driven by the interfacial tension, larger particles grow at the expense of smaller ones, that dissolve.2,3 This instability of the particle size distribution, can be a serious issue for emulsion or nanoparticle formulations, for example in pharmaceutical nanoparticle formulations of weakly soluble drugs.4, 6, 7 For emulsions, this coarsening mechanism is well established. The tension can be made relatively small, allowing for accurate measurements of the ripening rate using time resolved scattering experiments.5 Amorphous solid nanoparticles undergo Ostwald ripening similar to emulsions.4 Crystalline nanoparticles, on the other hand, seem not. This difference appears to be a consequence of activated crystal growth6,7 in combination with the fact that Ostwald ripening occurs very close to equilibrium. This will all be discussed in the light of recent experimental data. In addition, we will describe a direct link between Wilhelm Ostwald and Jan Skov Pedersen.
|Host: Professor Jan Skov Pedersen, iNANO & Department of Chemistry, Aarhus University