How do interactions control droplet size during nanoprecipitation?

Abstract

Nanoprecipitation provides colloidal dispersions through successive recombination events between nanometric objects. In the present article, we explain why the nanoprecipitation pathways induced through solvent-shifting – the Ouzo effect –, are fascinating study-cases. Indeed, they allow to address the question of how the interactions between the colloidal particles control the dynamics of the process, thus the particle size distribution. Experimental monitoring of the precipitation dynamics demonstrates that the colloidal dispersion polydispersity decreases over time as the droplets coalesce. Monte Carlo simulations within the Smoluchowski framework agree quantitatively with these observations, and show how the interactions between the particles naturally force the system to become nearly monodisperse. The mechanistic understanding gained from the solvent-shifting experiments is also relevant to other nanoprecipitation processes.