Conductivity and microviscosity of electrolyte solutions containing polyethylene glycols

Electrical conductivity of potassium chloride solutions containing polyethylene glycol (PEG) of different molecular mass was measured in a wide range of the polymer concentration up to 33 wt. % for PEG 300, 600, 2000, 4600, and 10 000. The data were used to find the dependence of microviscosity, $ηmicro,$ which characterizes the decrease of the ion mobility compared to that in the polymer-free solution, on the polymer volume fraction, φ. We find that the dependence is well approximated by a simple relation $ηmicro/η0=exp[kφ/(1−φ)],$ where $η0$ is viscosity of the polymer-free solution and k is a fitting parameter. Parameter k weakly depends on the polymer molecular mass growing from 2.5 for PEG 300 to its limiting value close to 2.9 for long chains. Using the φ-dependence of microviscosity, we give a practical formula for the conductivity of PEG-containing electrolyte solutions.