Short-Range Interactions between Polyions and Small Ions

A Kd = negative of the differential volume change per mole for the ionization of carboxylic acid groups 

OL = degree of ionization of polyacid pKo = chemical contribution to the pK of polyacids 

Eric Selegny (ed.), Polyelectrolytes, 79-85. All Rights Reserved. Copyright 1974 by D. Reidel Publishing Company, Dordrecht-Holland. 

Nevertheless, other polyelectrolyte properties have been shown to be sensitive to specific effects of univalent counter-ions. Such properties include electrophoretic mobility [15-18], molecular dimensions [15, 19], second virial coefficients [20, 21], solubility [15], distribution coefficients of two counter-ions in dialysis equilibrium between solvent and polyelectrolyte solution [22] and potentiometric titration behavior [11]. 

Depending on circumstances, the specificities can be demonstrated more directly by various methods involving spectroscopic, kinetic or thermodynamic techniques. The application of some of these techniques, such as NMR, ultrasonic absorption, and calorimetry is treated elsewhere. We shall review here results obtained in our laboratory by a dilatometric method [23, 24] and discuss some of the implications of these results to current theoretical treatments of polyelectrolyte solutions. The method involves the measurement of the volume change which occurs when a polyelectrolyte solution is mixed with a solution containing a specifically interacting counter-ion and is especially useful for studying the interaction of polyanions with metal and hydrogen 

---

SHORT-RANGE INTERACTIONS BETWEEN POLYIONS AND SMALL IONS... 

---