ISSN:
1435-1536
Schlagwort(e):
Key words Poly(N-vinylimidazole)
;
Polyallylamine
;
Acid-dissociation equilibria
;
Calorimetric titration
;
35Cl nuclear magnetic resonance
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
,
Maschinenbau
Notizen:
Abstract Thermodynamic parameters for acid dissociation of the conjugate acids of poly(N-vinylimidazole) and polyallylamine have been determined in the presence of sodium chloride and sodium nitrate. Even though the plots of ΔG 0 against the degree of dissociation, α, are highly dependent on the added salt concentration levels, the concentration effect has never been observed for the corresponding ΔH 0 versus α plots. The effect on the ΔG 0 versus α plots has been attributed to the entropy change of the counterions between a polyelectrolyte phase and a bulk solution phase. The α dependency of ΔH 0 is affected remarkably by the kinds of cationic polymers and counter-anions. Each ΔH 0 value at completely neutralized conditions is quite close to the corresponding ΔH 0 value of the monomer analog. The difference in the ΔH 0 values at fully charged conditions has been explained by the heats due to The ion-pair formation of chloride anion to the conjugate acids of poly(N-vinylimidazole) and polyallylamine has been supported by 35Cl NMR measurement. It has also been suggested that chloride anions bind the basic polymer molecules even at fully neutralized conditions.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/s003960050001
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