Dynamics of Molecular Associates in Methanol/Water Mixtures

Published

January 26, 2022

Author(s)

Yanqin Zhai, Peng Luo, Jackson Waller, Jeffrey L. Self, Leland Harriger, Y. Z., Antonio Faraone

Abstract

The dynamics of molecular associates in methanol/water mixtures was investigated using quasielastic neutron scattering. By measuring the signal from four methanol/water samples differing only by their isotopic composition, the relative motion of the water to methanol molecules, i.e. their mutual dynamics, was measured at the nanoscale. The thus obtained nanoscopic mutual diffusion coefficient signals a significantly slower process than the single particle diffusion of either methanol or water in the system as well as than their macroscopic mutual diffusion. The data do not provide any indication of microsegregation in this preeminent alcohol/water mixture; however, they do indicate the existence of long lived but dynamic molecular associates of water and methanol molecules. Analysis of the structural relaxation shows that the lifetime of molecular association through hydrogen bonding determines the fact that viscosity of the mixtures at intermediate concentrations is higher than that of both pure components.

Citation

Physical Chemistry Chemical Physics

Volume

24

Issue

4

Pub Type

Journals

Keywords

Water, methanol, association, hydrogen bond

Citation

Zhai, Y. , Luo, P. , Waller, J. , Self, J. , Harriger, L. , Z., Y. and Faraone, A. (2022), Dynamics of Molecular Associates in Methanol/Water Mixtures, Physical Chemistry Chemical Physics (Accessed October 9, 2025)