Two Opposite Effects of Alcohols in the Precipitation of Aqueous Nanocrystals

Abstract

In this work, we investigated the alcohols-based purification process of aqueous nanocrystals in simultaneous consideration of the interparticle-distance-dependent total interaction potential and the external structure of nanocrystals. Before nanocrystal precipitation, it is required to overcome an energy barrier, which is basically generated by the interparticle electrostatic repulsion. In the precipitation process of nanocrystals, alcohols possess two opposite effects. On the one hand, the addition of alcohols leads to the decreased relative dielectric constant of the mixture solution and the reduced interparticle electrostatic repulsion, which promotes the precipitation of nanocrystals. On the other hand, the ionic strength in the nanocrystal solution decreases after the introduction of alcohols. This leads to the increased interparticle electrostatic repulsion, which is adverse for the precipitation of nanocrystals. As a result, the precipitation process of aqueous nanocrystals should consider the int...