Colligative properties of polyelectrolyte solutions. V. Activity coefficients of counter‐ and by‐ions

Abstract

Simultaneous measurements of the activity coefficients of counter‐ and by‐ions in polyelectrolyte solutions were carried out. Sodium polyvinyl alcohol sulfate was used as the sample of polyelectrolyte and sodium chloride as the extraneous salt. The activity coefficient of sodium counter‐ion was determined by using a sodium amalgam electrode and that of chloride ion was determined by a sliver‐silver chloride elctrode. It was found that the activity coefficient of both counter‐ and by‐ions has little relationship with the volume of polymer coil, and that the additivity of counter‐ion activity found for hydrogen ion by Mock and Marshall holds also for sodium ion. It was also found that there is good agreement between the experimental results and the theory of Katchalsky and Lifson if we use their same theory for calculating the volume of polymer coil, although the volume is too large to be considered reasonable.

Monte Carlo Simulations of a Single Polyelectrolyte in Solution: Activity Coefficients of the Simple Ions and Application to Viscosity Measurements

“…We have already mentioned that the Debye-Hu ¨ckel approximation predicts the same activity coefficients for both counterions and co-ions (as long as no rescaling is performed). In contrast, both our simulations and experiments 48 show a large difference between the activity coefficients of the two species. We should therefore expect the Debye-Hu ¨ckel result to be a better approximation for the mean activity coefficient γ ( .…”

Polyelectrolyte Complexes

“…the substantial concentration of free K+ ions is decreased. 13 On adding micro-salts to polyelectrolytes, micro-ions carrying an electrical charge with the same sign as that of the macro-ions are excluded from the domains of macro-ions, while those carrying a charge of the opposite sign tend to be concentrated into the macro-ion domains. This latter effect leads to a reduction of the electrostatic potential of the macro-ion.…”

Interaction between parallel rodlike macroions

“…The concentration of small ions a t R (for the single rod system) is directly related to the osmotic pressure of the solution of the The additivity of the osmotic pressure of polyelectrolyte solutions containing low molecular salts was experimentally proved for several polyelectrolytes. [9][10][11] Now, from the above analyses on the extensive force of each rod and on the eoncentration of small ions a t R, it is concluded from (12) that the repulsive force between rods is not changed by the addition of salts. This is, however, under the following extreme conditions: ( A ) The rods are sufficiently thin; ( B ) the ratio a/R and X / R are sufficiently smaller than unity; (C) the salt concentration is not too high.…”