Properties of aqueous salt solutions of polyvinylpyrrolidone. I. Viscosity characteristics

The properties of dilute solutions of polyvinylpyrrolidone (PVP) in aqueous salt solutions have been studied by measurements of intrinsic viscosity [η] in theta and nontheta solvents. Intrinsic viscosities of the polymer solutions were observed to decrease upon addition of a variety of inorganic salts (phosphates, monohydrogen phosphates, carbonates, sulfates, and dihydrogen phosphates). Values of the Huggins constant, k_H, were found to be higher than 0.35 for PVP in pure water at 298 K, whereas in salt solutions they varied from 0.85 to 1.28 in nontheta solvents. Kraemer's constant, k_K, was also determined and k_H-k_K was calculated as 0.78 for PVP in pure water and for aqueous salt solutions of PVP, k_H-k_K = 0.61 at 298 K. k_H values were also higher than the predicted range of 0.5–0.7, and k_H-k_K values were noted to be 0.73 in theta solvents. © 1996 John Wiley & Sons, Inc.