PROPERTIES OF AQUEOUS SALT-SOLUTIONS OF POLY(ETHYLENE OXIDE) - THERMODYNAMIC QUANTITIES BASED ON VISCOSITY AND OTHER MEASUREMENTS

A previous study of poly(ethylene oxide) (PEO) in aqueous salt solutions has been extended to incorporate cloud-point measurements in potassium thiocyanate solutions and, particularly, viscosity measurements. A few osmotic-pressure measurements were made and molecular weights from gel-permeation chromatography (GPC) compared. The theta temperature for PEO in water from cloud points was found to be 369 plus or minus 3 degree K. An empirical linear relation has been found for sodium and potassiumn salts between the finite change of theta temperatures with change in ionic strength, the difference between the molar van der Waals volume and the partial molar volume of the salt. Values of the Huggins constant k prime are less than 0. 5 for PEO in pure water at 303. 2 degree K, indicating a good solvent, whereas in salt solutions they vary from 0. 59 to 1. 14 in nontheta solvents. Values of the characteristic ratio C//n, the steric parameter sigma , and the enthalpy and entropy of dilution parameters chi H and chi S have been calculated.