The preparation of poly(vinyl phosphonic acid) hydrogels as new functional materials for in situ metal nanoparticle preparation

Bulk poly(vinyl phosphonic acid) (p(VPA)) hydrogels were synthesized via a photo polymerization technique using polyethylene glycol diacrylate with different molecular weights as crosslinker. The prepared hydrogel was also used as template for in situ metal nanoparticle preparations of Co, Ni and Cu, by loading the corresponding metal ions from aqueous solution into the p(VPA) hydrogel networks and then reducing the metal ions with sodium boron hydride (NaBH4) within the hydrogel matrices. The amount of metal in hydrogel composites was determined by atomic absorption spectroscopy (AAS) and thermogravimetric analysis (TGA) measurements. Moreover, p(VPA)-M (M: Co, Ni, Cu, etc) were used as a soft reactor for the generation of hydrogen by hydrolysis of NaBH4, and in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). P(VPA)-Co composite demonstrated the best catalytic performance and its activation energy was calculated as 23.01 kJ mol(-1) which is comparable and mostly better than similar work in the literature. (C) 2012 Elsevier B.V. All rights reserved.