Miyamoto S, Imai N
Department of Physics, Faculty of Science, Nagoya University, Nagoya 464, Japan.
Biophys Chem. 1980 Jun;11(3-4):345-52. doi: 10.1016/0301-4622(80)87007-4.
The additivity rule of counterion activity or osmotic pressure in rodlike polyelectrolyte solutions has been discussed on the basis of the Fokker-Planck and Poisson equations in relation to the fluctuation of counterion distribution. This new theory has concluded that the additivity rule of counterion activity is less applicable than that of osmotic pressure due to the electric expansion force acting on the free-volume surface resulting from the fluctuation of counterion distribution. The theory has introduced an approximate relation between the counterion activities in the mixture solution of divalent and monovalent counterions, such that Deltaa+ = DeltaC++ - Deltaa++, in which Deltaa+ represents the increase of activity of monovalent counter-ions resulting from the addition of divalent counterionsDeltaC++, (in molar) to the solution, and Deltaa++ means the increase of the divalent counterion activity (in molar) in this process. This relation has been experimentally examined for Na-PSS solutions in the process of Cu2+ ion addition by the use of Na+ and Cu2+ sensitive electrodes, and it has been turned out that the relation is established in the low charge state of polyion.
基于福克 - 普朗克方程和泊松方程，结合反离子分布的涨落，讨论了棒状聚电解质溶液中反离子活度或渗透压的加和规则。该新理论得出结论：由于反离子分布涨落在自由体积表面产生的电膨胀力，反离子活度的加和规则比渗透压的加和规则适用性更差。该理论引入了二价和一价反离子混合溶液中反离子活度之间的近似关系，即Δa⁺ = ΔC⁺⁺ - Δa⁺⁺，其中Δa⁺表示向溶液中添加二价反离子ΔC⁺⁺（摩尔数）导致的一价反离子活度的增加，而Δa⁺⁺表示此过程中二价反离子活度（摩尔数）的增加。通过使用对Na⁺和Cu²⁺敏感的电极，在添加Cu²⁺离子的过程中对Na - PSS溶液进行了该关系的实验检验，结果表明该关系在聚离子的低电荷状态下成立。
