In situ formation of metal nanoparticle composites via "soft" plasma electrochemical reduction of metallosupramolecular polymer films

Metallosupramolecular polymers, consisting of both inorganic and organic phases, offer an interesting platform for the in situ formation of metal nanoparticles embedded in a polymer film. Here, we report the synthesis and characterization of Pt-containing supramolecular polymers, prepared from 4-oxy-2,6-bis(10-methylbenzimidazolyl)pyridine end-capped polymers of either poly(tetrahydrofuran) or poly(ethylene-co-butylene), where the OMeBip:Pt complex phase separates from the macromonomer soft core to yield mechanically robust films. Exposure of these Pt-containing supramolecular polymer films to an atmospheric-pressure plasma setup results in the controlled nucleation and growth of uniformly sized, crystalline, unagglomerated Pt nanoparticles. The mechanism for nanoparticle nucleation is believed to be reduction by plasma electrons, eliminating the need for hydrogen gas or other reactive chemicals and allowing "soft" processing. We show that the size and density of the nanoparticles is modulated by the exposure time, molecular weight of the polymer core, and polarity of the polymer core, thus enabling metal nanoparticle composites to be produced in a single step.