Amphiphilic gold nanoparticles formed at a liquid-liquid interface and fabrication of hybrid nanocapsules based on interfacial UV photodimerization

In this paper a novel method for fabrication of hybrid hollow capsules based on interface-directed self-assembly of gold nanoparticles (AuNPs) and interfacial photodimerization of anthracene is reported. A hydrophobic random copolymer with a disulfide group at the midpoint and pendant anthracene groups on the repeating units was synthesized by atom transfer radical polymerization. The hydrophobic random copolymer was dissolved in toluene and hydrophilic citrate-stabilized AuNPs were dispersed in water. An emulsion was obtained upon mixing of the two solutions. In the emulsion, hydrophilic AuNPs were able to undergo interface-directed self-assembly and amphiphilic AuNPs were produced at the liquid-liquid interface via ligand exchange. Hybrid nanocapsules with AuNPs on the surfaces were prepared after anthracene photodimerization at the liquid-liquid interface. Transmission electron microscopy, dynamic light scattering, UV-vis and scanning electron microscopy were used to characterize the structure of the hybrid nanocapsules. In the fabrication of the hybrid nanocapsules, the addition of small molecular surfactant has an important effect on the structures. The average size and size distribution of the hybrid nanocapsules can be controlled by controlling the concentration of the small molecular surfactant in the solution, and in the meanwhile the use of the small molecular surfactant will not reduce the surface density of AuNPs on the hybrid nanocapsules. The hybrid nanocapsules display effective catalytic activity in the reduction of 4-nitrophenol by NaBH4.