Ion binding from conductance and transference measurements in salt-free aqueous polyelectrolyte solutions

Abstract

The results of conductance and transference measurements on dilute, salt-free aqueous solutions of poly(4-vinyl-N-n-butyl pyridinium bromide) and poly(vinylbenzy1 trimethyl ammonium chloride) are recorded. From conductance and transference data the charge fraction of the polyions is found to remain essentially constant with dilution down to concentrations of less than 10-4 equiv/l. The principles of the methods used and the experimental details are critically discussed and the results compared with recent theories of ion binding in polyelectrolyte solutions. The effects of the dielectric constant of the solvent and of the temperature have been briefly studied and factors influencing the electrochemical properties of polyelectrolyte solutions are discussed.

Ion binding in polyelectrolyte solutions. An account for noncoulombic interactions

“…3 indicates that calculated value of D/Do depends primarily to the choice of A,, and to a much lesser degree to the value of the counterion counterion coefficient A,,. where A , = TpA is the basemolar conductivity of the polyion constituent, and A,(a c ) is the molar conductivity of free counterions. The latter quantity is usually replaced by the corresponding value for the same ion in the 1 : 1 electrolyte at the concentration equal to that of free ions a c [31].…”

Electrolytic conductivity of poly(1,3-propylene phosphate) solutions containing mono- and divalent-counterions

“…where the ratio of individual interaction parameters k = Fn/F m (10) can take the following values: k < 1, k = I and k > 1. Under the assumption that the equivalent conductivity of a polyion is practically independent of the counterion type (which seems reasonable for F m and Fn parameters not very different from each other) Eq.…”

“…The use of& or;t ~ is rather arbitrary and, as has been shown by Kurucsev et al [10], neither approach is strictly valid. Eq.…”

“…(1) and (2) has been interpreted by Wall et al [9] and by other authors [10][11][12][14][15][16][17][18] as the fraction of counter ions contributing to the conductance of the polyelectrolyte solution and called the "fraction of free counterions", the "polyion charge fraction" or the "transport parameter". According to Manning [13], F is related to the charge density parameter ~.…”

“…Some authors [10][11][12] have used ;t ~ the infinite dilution value, instead of ;to, i. e. they have employed Eq. (2)…”