DISSOCIATION OF POLY(ALLYLAMMONIUM) CATIONS IN SALT-SOLUTIONS

Potentiometric titration in various 1‐1 salt solutions was carried out to study the dissociation behavior of the poly(allylammonium) cation (PAAH+). The titration curves show that proton release from cationic PAAH+ is markedly suppressed by addition of simple salt and depends on the counterion species. From an analysis of the titration curves it is found that the electrostatic free energy change ΔGel upon the proton release is negative in all systems examined, and its absolute value decreases with increasing ionic strength of the medium. Also, at a constant added salt concentration (0.1 mol L−1) ΔGel depends significantly on the counterion species added and increases in the order $\[ {\rm ClO}_{\rm 4}^ - > {\rm NO}_3^ - > {\rm Cl}^ - > {\rm Br}^ - > {\rm SCN}^ - > {\rm I}^ - . \]$ The value of ΔGel correlates well with the electron donor constant En of the counterions. The dissociation behavior of PAAH+ is discussed in terms of electrostatic interaction among the ionized groups on the chain, the charge shielding effect, and the ion‐solvent interaction of the added counterions. Copyright © 1990 John Wiley & Sons, Inc.