DYNAMICAL STRUCTURE OF OLIGO(ETHYLENE GLYCOL)S WATER SOLUTIONS STUDIED BY TIME-DOMAIN REFLECTOMETRY

Dielectric relaxation measurements on water solutions of ethylene glyc ol 200 and 400, (degree of polymerization N = 4 and 9) in entire conce ntration region were carried out using a time domain reflectometry at 25 degrees C in the frequency range from 300 MHz to 20 GHz. For all th e samples, only one dielectric loss peak was observed in this frequenc y range, Plots of the relaxation strength and logarithm of the relaxat ion time calculated from apparent peak frequency of dielectric loss cu rves against monomer unit molar fraction of ethylene glycol X give str aight 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 approximate to 0.35 for N = 4 and X app roximate to 0.37 for N = 9, corresponding to the ratio of one ether ox ygen and 1.7 water. Analysis of these phenomena indicates that hydrati on 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 oxy gen can be inserted into water structure by replacing water oxygen. Th is hydration mechanism makes water structure stable. Ethylene glycol d issolves in water without much perturbation to water structure. (C) 19 98 American Institute of Physics.