The Preparation of Colloidal Precious Metal Particles Using Copolymers of Vinyl Alcohol–N-Vinylpyrrolidone

Abstract Precious metal particles of platinum and silver have been prepared by the reduction of metal salts dissolved in an aqueous solution of a copolymer of vinyl alcohol and N-vinylpyrrolidone with methanol. The stable platinum sols were obtained in the presence of poly(vinyl alcohol), poly(N-vinylpyrrolidone), and their copolymers, but their particle sizes hardly changed with the ratio of N-vinylpyrrolidone in the copolymer. On the other hand, colloidal stable silver sols were obtained only in the presence of a copolymer. Further, with an increase in the ratio of N-vinylpyrrolidone in the copolymer, the particle size of silver became small.