Dendritic Amphiphile Mediated One-Pot Preparation of 3D Pt Nanoparticles-Decorated PolyHIPE as a Durable and Well-Recyclable Catalyst

Straightforward organization of platinum nanoparticles (PtNPs) onto a macroscopic and robust material is described. PtNPs are in situ produced and stabilized by a dendritic amphiphile, where the latter consists of a hyperbranched polyethylenimine (PEI) as core and poly(styrene-co-2-ethylhexyl acrylate (P(St-EHA)) as shell. The resulting Pt@PEI@P(St-EHA), upon mixing with biphasic water and oil (a mixture of EHA and a dimethacrylate cross-linker in toluene), can self-assemble along the water/oil (W/O) interface and result in a stable emulsion. At W/O = 80/20 (volume ratio), a high internal phase emulsion (HIPE) forms and can be radically transformed into an open-cellular and elastic monolith termed Pt-polyHIPE, with PtNPs decorated on the surface. The Pt-polyHIPE is mechanically robust, and the cross-linking homogeneity by the dimethacrylate is responsible for the strength. The Pt-polyHIPE shows an active catalytic property, as evaluated by reduction of 4-nitrophenol. The material is conveniently and well recyclable, showing no decrease in catalytic activity at least within 20 cycles. Energy-dispersive X-ray spectra and thermogravimetric analysis also support sufficient retaining of the Pt species, where the multivalent and multiligand PEI should be responsible for this property.