Dielectric properties of water in the coexisting phases of aqueous polymeric two-phase systems

Abstract

Complex permittivity of aqueous solutions of poly(ethylene glycol)(PEG), polyvinylpyrrolidone (PVP), Ficoll, dextran and of the phases of aqueous dextran–PEG, dextran–PVP, and dextran–Ficoll biphasic systems of varied polymer concentrations have been measured at four frequencies in the range 10–24 GHz at 25 °C by an interferometric transmission method. It is found that the static dielectric constant of water is enhanced in all the polymer solutions directly with the polymer concentration. The polymers examined slow down the reorientational motion of water molecules and the polymer concentration effect decreases in the order PEG > PVP > Ficoll > dextran, in accordance with the order of decrease of the relative hydrophobicity of the polymers. It is also established that the dielectric relaxation times of water in the coexisting phases of the systems studies are different. The results obtained support the hypothesis that phase separation in an aqueous mixture of two polymers results in the appearance of two different coexisting structures of water formed under different influences of the phase polymers on orientation and intermolecular interactions of the water molecules.