Preparation of simple and mixed nickel and cobalt molybdates using hybrid precursors made from an ordered polymermatrix and inorganic salts

Abstract

The amphiphilic poly(ampholyte) poly(N,N-diallyl-N-hexylamine-alt-maleic acid), bearing simultaneously carboxylic acids, amines and hydrocarbon side chains, was used as a matrix to stabilize inorganic ion species (anionic as well as cationic) generated in aqueous solution from Ni(NO₃)₂·6H₂O, Co(NO₃)₂·6H₂O and (NH₄)₂MoO₄. Drying produces hybrid organic–inorganic blends which, due to the amphiphilicity of the copolymer, exhibit supramolecular organization in the bulk. Solid state studies show that up to two moles of metal cations (alone or together with metal anions) per repeat unit of the copolymer can be blended without loss of homogeneity in the hybrid material. A systematic screening permitted the determination of the optimal conditions for the preparation of homogeneous blends. Thermal treatment of the hybrid materials produces simple and mixed nickel and/or cobalt molybdates. The α- as well as the β-phase were obtained, and the mixed structures are solid solutions of simple NiMoO₄ and CoMoO₄.