Capitalizing on Aggregation to Chaperon NPs Across Fluid Interfaces

The transfer of nanoparticles (NPs) from one liquid phase to a second immiscible phase is important in the synthesis, processing, and modification of nanoparticles. However, aggregation of NPs in the solution has long been considered as an undesirable phenomenon, which is regarded as a sign of failure for NPs transfer to another phase. Here, we take advantage of the aggregation to realize a ligand-induced NP transfer. Using oppositely charged amphiphilic polymers, we show that mono-disperse NPs that aggregate in an aqueous phase can be transferred to an oil phase where the aggregates are effectively dissolved, delivering NPs that disperse in the oil phase. This new transfer path challenges the conventional conception of the unsuccessful phase transfer due to NPs aggregation. By jamming the NP-polymer assembly at the liquid/liquid interface, the transfer process can be inhibited. The charged amphiphilic polymers effectively act as chaperons for the NP transfer and provide a unique way to manipulate the dispersion and distribution of the NPs in two immiscible liquids when they are brought into contact.