The effect of macromolecular crowders on dielecric constant of aqueous electrolyte solutions

The effect of poly(ethylene glycol) (PEG) of different molecular weight (e.g. PEG4000 and PEG12000) on the mean activity coefficient of sodium chloride in aqueous solutions was investigated at 298 K, using electrochemical measurements, as well as theoretical HNC integral equation theory. The experimental results are consistent with experimental prediction: the addition of the neutral component into the solution increases the activity coefficient of the NaCl salt, that does not approach to unity at low electrolyte concentration. The results of the HNC theory were, in combination with the experiment, used to obtain the relative dielectric constant of the PEG/water/NaCl solutions. As observed previously, the addition of PEG decreases the relative dielectric constant of the solution, the reduction being dependent on the salt concentration. The effect of salt concentration is less pronounced in the case of larger PEG molecules of the same weight fraction. (C) 2021 Elsevier B.V. All rights reserved.