Covalent Immobilization of Ultrafine Platinum Particles onto Crosslinked Polymer Support and Their Application to Catalysis

Ultrafine particles of platinum were prepared as stable aqueous dispersions by a photoreduction method in the presence of soluble protective polymers. By use of the protective polymer with methyl acrylate residues as a reactive group, the polymer-protected ultrafine platinum particles were successfully immobilized onto crosslinked polymer supports with amino groups. The present immobilization was attributed to the formation of amide bonds by the reaction of methyl acrylate residues in the protective polymer with amino groups in the support, and the immobilization mechanism was investigated by the model reaction using protective polymer with p-nitrophenyl acrylate residues as a reactive group. The immobilized platinum particles obtained show high catalytic activity for hydrogenation of olefins and specific substrate selectivity due to a hydrophilic–hydrophobic interaction between the support and the substrate.