Dielectric properties of polyelectrolytes. III. Effect of divalent cations on dielectric increment of polyacids

✍ Scribed by Akira Minakata

• Publisher: Wiley (John Wiley & Sons)
• Year: 1972
• Tongue: English
• Weight: 627 KB
• Volume: 11
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1972.360110804

✦ Synopsis

Abstract

Dielectric dispersion of polyacrylic acid (PAA) and polystyrene sulfonic acid (PSS) was measured in the presence of divalent cations. Effects of divalent ions were studied by neutralization with varying ratios of sodium hydroxide and divalent base concentration, addition of salts of divalent cations, and neutralization with divalent bases only. Two dispersion regions were observed in all cases, i.e., low‐frequency dispersion (10^2^–10^4^ Hz) and high‐frequency dispersion (10^5^–10^6^ Hz). The dielectric increment increases in the presence of sodium and alkaline earth metal ions together, but not with sodium and transition metal ions. This is due to the increment of low‐frequency dispersion and is attributable to the fluctuation of bound counterions which is explained by our theory previously reported.^1^ In the case of PAA neutralized with large fractions of divalent ions, or with divalent ions only, the increment is very small because of reduction of the fluctuation by interaction between bound ions at the neighboring sites and reduction of the effective length of polyion probably due to chelation by divalent ions. There are some differences among the effects of Mg^++^, Ca^++^, and Ba^++^ on dielectric increment which may result from affinity or chelating ability of these ions.