Trapping Metal Nanoclusters in “Soap and Water” Soft Crystals

Rods and dots: Quantum dots (2–5 nm in diameter) of copper, silver, gold, palladium, and ruthenium are easily trapped in self-assembled “soft crystal” gels made of water and surfactants. The gels are made of long micellar rods in direct hexagonal packing, aqueous outside and oily inside (see picture). The hydrophobic interaction between the clusters, stabilising shell, and the oily phase keeps the clusters inside. The use of toluene, instead of cyclohexane, is the key to enable the trapping of very small clusters of various metals in tight confinement. Structural development is monitored by small-angle Xray scattering (SAXS). The possible applications of this discovery to make thin nanowires by cold-welding and design of new nanocatalyst templates are discussed.