Binding of acrylic and sulphonic polyanions by open-chain polyammonium cations

The interactions between some acrylic and sulphonic polyanions and some pro tonated amines (diamines NH2-(CH2)(x)-NH2, x = 2,...,10; linear tri-, tetra -, penta- and hexa-amines) were studied potentiometrically in aqueous solut ion, at 25 degreesC. For both types of polyanions AL(2)H(1) (L-, monomer of polyanion, A, amine) species are formed, with i = 1,...,n (n = number of a mino groups in the amine). The stability of these species is strictly depen dent on the polyammonium cation charge, and fairly independent of the type of amine tin diamine species maximum stability is observed for x = 4, 5). A crylic and sulphonic polyanion complexes are considerably stronger than ana logous species formed by low molecular weight anions. Mean stability can be expressed as log K= 2.87 zeta (2/3), for polyacrylic anions and log K= 2.4 2 zeta (2/3) for polysulphonic anions (zeta = absolute value for charge pro duct of reactants). (C) 2001 Elsevier Science B.V. All rights reserved.