Precipitation of Polyelectrolytes in the Presence of Multivalent Salts - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal de Physique II Année : 1995

Precipitation of Polyelectrolytes in the Presence of Multivalent Salts

J. Wittmer
A. Johner
J. Joanny

Résumé

We present a theory of the complexation of polyanions by divalent cations. The formation of both mono-and dicomplexes is possible. Monocomplexation locally inverts the charge of the polyelectrolyte and transforms it into a polyampholyte. The formation of a dicomplex creates a bridge between charged monomers. The complexation constants for mono and dicomplexation strongly decrease at high ionic strength. If the complexation constants are large enough, the polyelectrolyte precipitates at moderate salt concentrations. The precipitation is driven either by a Debye-Hückel polarisation energy as in polyampholytes (for almost pure monocomplexation) or by the bridging attraction induced by the dicomplexes. The equilibrium constant for the transformation of two monocomplexes into a dicomplex (at vanishing ionic strength) is a key parameter: - when monocomplexation is favored, the polymer is redissolved by strong charge inversion at moderate salt concentrations. Two successive polymer precipitations and solubilisations can be observed as the divalent salt concentration is increased. - when dicomplexation is favored, the precipitation at moderate salt concentration is followed by a redissolution at high ionic strength where complexation becomes unefficient. Only one precipitation is expected.

Domaines

Articles anciens
Fichier principal
Vignette du fichier
ajp-jp2v5p635.pdf (1.03 Mo) Télécharger le fichier
Origine : Accord explicite pour ce dépôt

Dates et versions

jpa-00248185 , version 1 (04-02-2008)

Identifiants

Citer

J. Wittmer, A. Johner, J. Joanny. Precipitation of Polyelectrolytes in the Presence of Multivalent Salts. Journal de Physique II, 1995, 5 (4), pp.635-654. ⟨10.1051/jp2:1995154⟩. ⟨jpa-00248185⟩

Collections

AJP
72 Consultations
387 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More