Solution Properties of Water–Poly(ethylene glycol)–Poly(N-vinylpyrrolidone) Ternary System

Abstract

Viscosity and density measurements as well as determination of binodal curves were made for a water–PEG–PVP ternary system. In the system, a hydrodynamic interaction parameter Δb23 suggested that a repulsive interaction worked between PEG and PVP molecules and the strength of interaction became strong with increasing molecular weight of the samples. Temperature dependence of partial specific volume v could be explained in terms of the amount of hydrated water attracted by each polymer chain. Molecular weight and temperature dependence of binodal curves were obviously related to those of Δb23. Consequently, it is considered that Δb23 is closely related to the Flory–Huggins interaction parameter χ23. However, binodal curves were only partially consistent with the Flory–Huggins theory for the solvent 1–polymer 2–polymer 3 ternary system. To explain the binodal behavior, χ23 is not only a function of temperature but also a function of polymer-composition as well as that of Δb23. The hydration of each polymer chain relating to interaction parameters χ21 and χ31 is also an important factor for the binodal behavior.