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Inference on ion binding to polyelectrolytes from emulsion rheology

1981; Elsevier BV; Volume: 82; Issue: 1 Linguagem: Inglês

10.1016/0021-9797(81)90123-5

1095-7103

John Ralston, T. van Vliet, J. Lyklema,

Material Dynamics and Properties

Extending a previously developed technique, we studied the rheological properties of paraffin oil in water emulsions, stabilized by partially esterified polymethacrylic acid (PMA-pe) in the presence of NaI, CaII, CdII, MnII, CuII, and NiII. In addition, the conformational transition of PMA-pe as a function of pH in the presence of these ions was studied potentiometrically. The formation of cation bridges between PMA-pe molecules adsorbed on different particles leads to high storage moduli, which are found at low α for CdII and at intermediate a for the other divalent cations. The binding strength of the cation and the polyelectrolyte increases in the order NaI < CaII < MnII < NiII < CdII. Screening of the charges is dominated by the valence of the counterions and not significantly by their nature. The Gibbs energy of the conformational transition is insensitive to the valence and nature of the cation.