Investigations on the dissociation behaviour of hydrolyzed alternating copolymers of maleic anhydride and propene .1. Potentiometric titrations

The potentiometric behaviour of hydrolyzed copolymers of maleic anhydride and propene was studied as a function of added;salt (LiCl, NaCl, KCl, CaCl2). The first and second apparent ionization values pK(a1) and pK(a2) obtained by the classical interpretation were found to depend on the ionic strength and the counterion, respectively. The influence of the two configurations of the succinic moieties causing four dissociation constants is discussed. The effect of added salt was observed to be the greatest in the presence of CaCl2. Hence the addition of CaCl2 enables determination of the concentration of other copolymers of maleic anhydride obtained from the neutralisation of the second carboxylic group. Copyright (C) 1996 Elsevier Science Ltd.