Synthesis, characterization, and catalytic activity of crosslinked poly(N-vinyl-2-pyrrolidone acrylic acid) copolymer-metal complexes

This article describes the development of a new crosslinked poly(N-vinyl-2-pyrrolidone acrylic acid) copolymer for potential applications in catalase-like activity for the decomposition of hydrogen peroxide. The copolymer, crosslinked with hexanediol diacrylate (4 mol %), was prepared by the suspension polymerization of the monomers in water. The metal-ion complexation of copolymer-derived sodium salts was investigated for Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) ions. The metal uptake varied in the following order: Cu(II) > Cr(III) > Mn(II) > Co(II) > Fe(III) > Ni(II) > Zn(II). The polymer and metal complexes were characterized by C-13 cross-polarity/ magic-angle spinning NMR, Fourier transform infrared, ultraviolet-visible, electron paramagnetic resonance, thermogravimetry, and scanning electron microscopy analyses. The catalase-like activities of these insoluble metal complexes were investigated for the decomposition of hydrogen peroxide. Co(II) and Cu(II) complexes were effective for the catalytic decomposition of hydrogen peroxide. The catalytic decomposition was first-order. The effects of various parameters, such as the time, temperature, pH, amount of the catalyst, concentration of hydrogen peroxide, and recyclability of the catalyst, were examined.