New method for deriving the intrinsic viscosity of polyelectrolytes

Intrinsic Viscosities of Polyelectrolytes: Determination and Modeling of the Effects of Extra Salt

“…One of them, the so-called isoionic dilution, was already proposed [10] by Hermans and co-workers in a second letter to the editor. In this contribution the authors demonstrate that it is possible to avoid the maxima occurring in plots of the type shown in Figure 1 by "measuring the viscosity at various polymer concentrations in a series of electrolyte solutions in such a manner that the total ionic strength of the solution is kept constant".…”

“…In contrast to the normal procedure it does not use a solvent of constant salinity, but increases the concentration of salt to the extent the dilution proceeds. According to experience with the present system [10] h spec /c becomes a linear function of c if 1.5 millimoles of NaCl are considered as "equivalent" to 1 milliequivalent of the polyelectrolyte. In other words, if c salt denotes the concentration of NaCl in millimoles per liter and g the polyelectrolyte content in milliequivalents per liter, Equation (5) …”

“…[8] Herein, we use the approach to reevaluate early experiments by Pals and Hermans. [9][10][11] In particular, we are interested to check whether the new relation accounts for the extrema observed in the Huggins plots for polyelectrolytes and to which extent the results of the approach of isoionic dilution, proposed by Hermans and co-workers, agree or disagree with the new evaluation. Special attention is paid to intrinsic viscosities of polyelectrolytes in pure water and to the effects of rising amounts of external salt on [h].…”

“…The measurements [11] were performed at 27 8C. Huggins plot (isoionic experiment [10] ) for solutions of pectin-Na in aqueous NaCl solutions of variable composition as described by Equation (5) www.chemphyschem.org plicable to charged and uncharged, [7] linear or non-linear macromolecules [Eq. (6)]: [8] ln…”

Structure–property relationships for a series of polyimide copolymers with sulfonated pendant groups

“…Attempts to mitigate the polyelectrolyte effect by the addition of 1 wt% LiCl to the DMSO solution in the form of an aqueous solution [67,68] were unsuccessful as the polymer precipitated from solution upon addition of aqueous LiCl. The reduced viscosity measured according to the method reported by Pineri et al [69] using m-cresol as solvent and a triethylammonium salt as the counter ion for concentrations of 0.5 g/dL of 8d is w4.7 dL/g.…”