Acoustic investigations of pseudo-stable structures in aqueous solutions of polyethylene glycols

The velocity of ultrasound ðcÞ and the density ðrÞ have been measured in mixtures of water and polyethylene glycols in the temperature range from 288 to 328 K. Based on the data obtained, the adiabatic compressibility coefficients ðbadÞ have been calculated from Laplace’s equation. The variations of c; r and bad with concentration (m; mole fraction) and temperature have been studied. Structural interactions and the formation of a compact pseudo-stable structure in the region of very low polyethylene glycol concentrations have been reported. The structure built from these mixtures can be neither of the liquid clathrate-like hydrate type I nor type II. q 2004 Elsevier B.V. All rights reserved