https://doi.org/10.1051/epjconf/202227201003
Unexpected molecular dynamics of ethanol in hydrogen-bonded binary mixtures, ethanol-octanol and ethanol-water
1
Institut Laue-Langevin, 38000 Grenoble, France
2
Laboratoire Interdisciplinaire de Physique, CNRS and Univ. Grenoble-Alpes, 38402 Saint Martin d’Hères, France
3
Institute of Physical and Theoretical Chemistry, University Regensburg, Universitätstraße 31, 93053 Regensburg, Germany
4
Laboratoire Leon Brillouin, Paris-Saclay University. CEA, CNRS, 91171 Gif-sur-Yvette, France
* e-mail: hoffmann@ill.fr
** e-mail: marie.plazanet@univ-grenoble-alpes.fr
Published online: 17 November 2022
In view of getting a quantitative picture of the dynamics in mixtures of hydrogen-bonded liquids, in particular the ternary water-ethanol-octanol, we examine in this paper the dynamics of two binary systems: ethanol-water and ethanol-octanol. Our multiscale investigation includes quasi-elastic neutron scattering for the characterization of the dynamics at the molecular scale, completed by NMR at the mesoscopic scale and eventually compared with macroscopic viscosity properties. We highlight the decrease of diffusivity in pure alcohols when increasing the lengthscale and conjecture its relation with the two processes measured in dielectric spectroscopy. While the behaviour of ethanol-water is well understood, unexpected inversion of the slowest component between the micro and the mesoscale are evidenced in the ethanol-octanol mixture. This effect could be at the origin of the negative viscosity excess in the mixture of alcohols.
© The Authors, published by EDP Sciences, 2022
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
