Study of Metal-Polycarboxylate Complexes Employing Ion-selective Electrodes. II. Stability Constants of Copper(II) Complexes with Poly(acrylic acid) and Poly(methacrylic acid)

The copper(II) complex formation with poly(acrylic acid) and poly(methacrylic acid) in aqueous solution was studied by potentiometric titration employing glass and copper(II) ion-selective electrodes. The values of the equilibrium constants of the complex formation and the stability constants were estimated in various degree of neutralization. Since the concentration of free copper(II) ions could be determined by employing the copper(II) ion-selective electrode, the concentrations of two complex species, involving one and two carboxylato groups, were determined from stoichiometric equations. The equilibrium and stability constants of the complexes obtained were observed to pass through peaks with increase in the degree of neutralization. The order of magnitude of the equilibrium constant of the polyacrylate complex was larger than that of the polymethacrylate complex.