Self-assembly of soft nanoparticles with tunable patchiness

Details of the forces between nanoparticles determine the waysin which the nanoparticles can self-assemble into larger structures.The use of directed interactions has led to new conceptsin self-assembly such as asymmetric dendrons1,2, Janus particles3,patchy colloids46 and colloidal molecules7. Recentmodels that include attractive regions or patches on thesurface of the nanoparticles predict a wealth of intricatemodes of assembly812. Interactions between such particlesare also important in a range of phenomena including proteinaggregation13,14 and crystallization15, re-entrant phase transitions1618, assembly of nanoemulsions19 and the organizationof nanoparticles into nanowires20. Here, we report the synthesisof 6-nm nanoparticles with dynamic hydrophobicpatches and show that they can form reversible self-assembledstructures in aqueous solution that become topologically moreconnected upon dilution. The organization is based onguesthost supramolecular chemistry with the nanoparticlescomposed of a hydrophobic dendrimer host molecule andwater-soluble hydrophilic guest molecules. The work demonstratesthat subtle changes in hierarchal composition and/orconcentration can dramatically change mesoscopic ordering