AbstractThe possible dependence of the “unperturbed dimensions” of ionizable polymer chains on the charge density along the macromolecular chain is discussed in the light of theoretical studies and of experimental evidence. Some experiments on the behavior of dicarboxylic acids are suggested which would provide information useful in the interpretation of the behavior of polycarboxylic acids. A kinetic study of intramolecular reactions of polyions carrying small numbers of randomly spaced reactive and catalytic groups is proposed as a means to characterize chain flexibility. Finally, the advantages are pointed out which result from supplementing data on the ionization equilibrium of polymeric acids with calorimetric d