Dynamical structure of oligo(ethylene glycol)s-water solutions studied by time domain reflectometry

Abstract

Dielectric relaxation measurements on water solutions of ethylene glycol 200 and 400, (degree of polymerization N=4 and 9) in entire concentration region were carried out using a time domain reflectometry at 25 °C in the frequency range from 300 MHz to 20 GHz. For all the samples, only one dielectric loss peak was observed in this frequency range. Plots of the relaxation strength and logarithm of the relaxation time calculated from apparent peak frequency of dielectric loss curves against monomer unit molar fraction of ethylene glycol X give straight lines in the region of 0<X<0.35 for N=4, and 0<X<0.37 for N=9. Shapes of dispersion and absorption curves exhibit critical change at the concentration X≈0.35 for N=4 and X≈0.37 for N=9, corresponding to the ratio of one ether oxygen and 1.7 water. Analysis of these phenomena indicates that hydration complex of one ether oxygen and 1.7 water is formed, and the 1:1.7 complex behaves as one kind of component corresponding to 2.7(=1+1.7) waterlike molecules in the solution. It is suggested that ether oxygen can be inserted into water structure by replacing water oxygen. This hydration mechanism makes water structure stable. Ethylene glycol dissolves in water without much perturbation to water structure.

Interaction between poly(ethylene glycol) and water as studied by differential scanning calorimetry

“…Sato and coworkers obtained a similar result of 1.7 water per one ether oxygen for PEG400 -water system by employing time domain reflectometry. 28 The eutectic point temperature shifted to high temperature and the eutectic point composition shifted to low concentration of PEG with increasing molecular weight. Then the maximum bonding water number per EG unit increased with increasing molecular weight.…”

Dielectric spectroscopy study on ionic liquid microemulsion composed of water, TX-100, and BmimPF6

“…The lengths of the inner and outer conductor are 10 mm and 25 mm, respectively. From 200 MHz to 20 GHz, time domain reflectometry 20 was employed, which is coupled with a flatend capacitor cell 21 using a 2 mm semi-rigid coaxial waveguide. All measurement was carried out at 25…”

“…• C. The temperature was controlled by using a Compact Ultra Low Temperature Chamber (MC-811, ESPEC Corp., Japan) or by a water jacket 21 connected with a bath that is filled with water/ethylene glycol mixture.…”

Molecular Interactions in Poly(ethylene glycol)–Water Mixtures at Various Temperatures: Density and Isentropic Compressibility Study

“…When, on the other hand, Figure 1. Relative dielectric relaxation times (*, X=t [11,15] ) and shear viscosities (*, X= h s …”