Ultra-long palladium nanoworms by polymer grafts

摘要

Chemically and morphologically stable, non-aggregating palladium nanoworms with diameters of 2 nm and lengths of up to 10 nm with a graft-to polystyrene shell were synthesized in a straight-forward one-phase system, and proof for the mechanism of formation is presented. The synthesis has been achieved by the application of ω-2,2′-bipyridyl-polystyrene as stabilizer, which led to a "graft-to" structure of palladium nanoworms with polystyrene shell. The nanoworms have been characterized by TEM, XRD, and coupled GPC-UV/Vis measurement. It was possible to show that the formation of nanoworms proceeds by agglomeration of spherical palladium nanoparticles. This mechanism was transferred to ω-thiol-polystyrene as stabilizer, which results in either spherical nanoparticles (low ratio Pd:Polymer, <2 nm diameter) or high aspect ratio nanoworms (high ratio Pd:Polymer, up to 10 × 120 nm), proving that the formation of palladium nanoworms was not exclusive for pyridine/amine-based ligands. Graphical abstract: In a straight-forward one-phase synthesis, palladium nanoworms with a graft-to polymer shell are synthesized by metal salt reduction. The picture shows a sample of palladium nanoworms with diameter of 10 nm and lengths of up to 120 nm, stabilized by ω-thiol-polystyrene.