Effect of the Degree of NNMBA Crosslinking on the Physicochemical Characteristics and Catalytic Activity of 4–20 mol% NNMBA‐Crosslinked Polyacrylic Acid–Metal Complexes

Abstract

Metal complexation behavior and catalytic activity of 4–20 mol% N, N′‐methylene‐bis‐acrylamide (NNMBA)‐crosslinked polyacrylic acids were investigated. The polymeric ligands were prepared by solution polymerization. The metal ion complexations were investigated towards Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) ions. The metal uptake followed the order: Cu(II) > Cr(III) > Mn(II) > Co(II) > Fe(III) > Zn(II) > Ni(II). The polymeric ligands and the metal complexes were characterized by various spectral methods. The catalytic activity of the metal complexes were investigated towards the hydrolysis of p‐nitrophenyl acetate and Co(II) complexes exhibited high catalytic activity. The kinetics of catalysis was found to be first order. The hydrolysis was controlled by pH, time, amount of the catalyst, and temperature. The metal complexation and catalytic activity were influenced by the degree of NNMBA crosslinking. Thus, 4 mol% NNMBA‐crosslinked polyacrylic acid system has the highest metal ion complexation and catalytic activity among the four NNMBA‐crosslinked polyacrylic acid systems.