Metal Nanoparticle Foundry with Redox Responsive Hydrogels

A redox-active, organometallic hydrogel is successfully formed from the reaction of poly[ferrocenyl(3-bromopropyl)methylsilane] with a multifunctional amine cross-linker, N,N,N′,N″,N″-pentamethyldiethylenetriamine. When the poly(ferrocenylsilane) (PFS) hydrogel is charged with noble metal salts, corresponding noble metal nanoparticles are formed. Interestingly, the nanoparticles are well dispersed in the hydrogel matrix and little or no aggregates are observed. The noble metal nanoparticles, which include Au, Ag, Pd, Pt, Ir, and Rh, are characterized by transmission electron microscopy, energy dispersive X-ray, and X-ray photoelectron spectroscopy. The concept of using a redox-active hydrogel for fabricating noble metal nanoparticles, where the PFS network chains provide confinement, and where no external reducing agents or ligands are required, is demonstrated to be effective