Stability constants of water-soluble and latex types of chelating polymers containing iminodiacetic acid with some transition-metal ions

Two polymeric chelating agents, water-soluble and latex types of poly(styrene-co-GMA-IDA), are formed by reacting styrene with a chelating vinyl monomer, GMA-IDA. Acid dissociation constants (K-a) and stability constants (K-s) of these chelating agents with Cu(II), Ni(II), Zn(II) and Co(II) are determined by potentiometric titration and UV-Vis spectrophotometer, respectively. The values of K-a1 and K-a2 for the latex type of poly(styrene-co-GMA-IDA) are smaller than those for solution types. Stability constants are ordered, latex types > solution types > GMA-IDA. Latexes are surfactant-free, nearly nano-particles and the mean size declines as the amount of metal ions increases, when the particles are complexed therewith. The stability constants of the latex-metal complexes exceed those of the corresponding GMA-IDA-metal complexes by a factor of 10(2)-10(3), depending on the metal ions. These results are explained by the neighboring effect and high concentrations of GMA-IDA on latex's particulate surface (cooperative effect). (C) 2002 Elsevier Science Ltd. All rights reserved.