A Kinetic Study of Poly(acrylic acid)-Copper(II) Interactions in Aqueous Solutions

Article abstract of DOI:10.1246/bcsj.55.3413

Concentration-jump kinetic studies of the aqueous poly(acrylic acid)-copper(II) system reveal the presence of a relaxation phenomenon in the time range of 10² ms.Kinetic data under various pH's and compositions, together with the potentiometric results, indicate that this relaxation effect is due to the following complex-formation reaction: where L2^3- is a coordination unit consisting of two adjacent carboxylato side groups on the polymer chain.The specific features of the pH dependence of the τ^-1 value are discussed in relation to the degree of dissociation of the carboxyl groups.The rate and stability constants of the reaction are determined to be: k₂ = 5.6 * 10³ M^-1 s^-1 (1M = 1 mol dm^-3), k_-2 = 0.7 s^-1, and K₂ (=k₂/k_-2) = 7.9 * 10³, at pH 7.0, I ca. 0, and 25 deg C.The overall complex-formation mechanism, involving the very rapid formation of CuL2, is discussed.