Effect of Temperature and Solvent Composition on the Intrinsic Viscosity of Poly(ethylene glycol) in Water−Ethanol Solutions

Abstract

In this work, the intrinsic viscosities of poly(ethylene glycol) (PEG) with a molar mass of 20 kg · mol -1 were measured in water-ethanol solutions from (283.1 to 313.1) K. The expansion factors of the polymer chains were calculated from the intrinsic viscosity data. The thermodynamic parameters (entropy of dilution parameter, the heat of dilution parameter, θ temperature, polymer-solvent interaction parameter, and second osmotic virial coefficient) were derived by the temperature dependence of the polymer chain expansion factor. The thermodynamic parameters indicate that mixtures of water-ethanol are changed to the poorer solvents for PEG by increasing temperature. Also the thermodynamic parameters indicate that water-ethanol mixtures are changed to the poorer solvents for PEG by increasing volume fractions of ethanol.

Investigation on the Interactions of Poly(ethylene oxide) and Ionic Liquid 1-Butyl-3-methyl-imidazolium Bromide by Viscosity and Spectroscopy

“…The value of l in the case of PEO is equal to the average of bond lengths for (C–C) and (C–O). These bond lengths are l C–C = 0.153 nm and l C–O = 0.143 nm …”

“…In a good solvent, long-range interactions take place and the polymer molecule expands. The expansion factor, α, which describes the excluded volume effect, is given by , where M, N, l , and ϕ are molecular weight of polymer, number of bonds existing in the polymer chain, bond length, and bond angles, respectively. Φ is the Flory constant which equals 2.8 × 10 20 .…”

“…In a good solvent, long-range interactions take place and the polymer molecule expands. The expansion factor, α, which describes the excluded volume effect, is given by 19,20…”

“…These bond lengths are l C−C = 0.153 nm and l C−O = 0.143 nm. 19 Flory and Fox further suggested that the temperature dependence of the expansion factor is as follows: 22 α α π…”

Thermodynamic study of poly(ethylene glycol) in water/acetone solutions by viscometry

“…The previous fi ndings indicate that water is a good solvent for poly(ethylene oxide) at low temperatures, and water approaches a θ solvent for poly(ethylene oxide) with increasing temperature [13 -15] . The previous fi ndings indicate that a water/ethanol mixture is a poorer solvent for poly(ethylene oxide) than pure water [10,16,17] . The aim of this study was to determine the effect of temperature on the intrinsic viscosities of PEG, in mixtures of water/ acetone and calculate some of the thermodynamic parameters by temperature dependence of expansion factor of the polymer chain.…”