Dissociation of poly(allylammonium) cations in salt solutions

✍ Scribed by Hiroshi Ochiai; Yasushi Anabuki; Osamu Kojima; Kazuyuki Tominaga; Ichiro Murakami

• Book ID: 105338190
• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 416 KB
• Volume: 28
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/polb.1990.090280209

✦ Synopsis

Abstract

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 Δ__G__~el~ 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^) Δ__G__~el~ 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 Δ__G__~el~ 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.