Nanoparticles with Fe3O4−Nanoparticle Cores and Gold-Nanoparticle Coronae Prepared by Self-Assembly Approach

Polystyrene (PS) brushes on Fe3O4 nanoparticles were prepared by reversible addition−fragmentation chain transfer (RAFT) polymerization, and after reduction reaction PS brushes with terminal thiol groups (HS−PS−Fe3O4NPs) were obtained. Citrate-stabilized gold nanoparticles (AuNPs) were prepared in aqueous solution and HS−PS−Fe3O4NPs were dispersed in toluene. Upon mixing of the aqueous solution with the toluene solution, a stable O/W emulsion was prepared. Hydrophilic gold nanoparticles interacted with hydrophobic Fe3O4 nanoparticles via Au−S interaction, and amphiphilic nanoparticle complexes were formed at the liquid−liquid interface. The stability of the emulsion was achieved by the formation of the amphiphilic nanoparticle complexes. Upon transfer of the emulsion into excess methanol, core−shell structures with Fe3O4−nanoparticle cores and gold−nanoparticle coronae were fabricated. In this manuscript, the influences of the weight ratio of HS−PS−Fe3O4NPs to AuNP and volume ratio of toluene to water on ...