Joachim Koetz

Nanoparticle interactions can mediate assemblies and self‐organization into colloidal superstructures, if then control of the size and stabilization is highly required towards the fabrication of functional nanomaterials. In the proposed approach, different types of water‐dispersible and oil‐dispersible nanoparticles were incorporated in water‐in oil (w/o) microemulsions stabilized by Aerosol‐OT (AOT) as surfactant. Phase separation at higher surfactant and water contents resulted in the formation of a heterocoagulate, which can be separated with an external magnet. This magnetic heterocoagulate, which can contain 3 different types of nanoparticles, can be dispersed in longer‐chain carboxylic acids. An additional phase‐transfer into oil‐in water (o/w) dispersions was mediated by an auxiliary surfactant in water‐ethanol. The resulting nanostructures from heterocoagulates formed at higher temperatures consisted on inner domains of water‐dispersible nanoparticles embedded in a matrix‐shell of oleyl‐capped nanoparticles. Thus, a new encapsulation strategy is achieved under relative mild conditions, combining three types of nanoparticles and providing compartmentalization and magnetic‐responsiveness.