Affordable Access

deepdyve-link deepdyve-link
Publisher Website

Dynamics of water-alcohol mixtures: insights from nuclear magnetic resonance, broadband dielectric spectroscopy, and triplet solvation dynamics.

Authors
  • Sauer, D
  • Schuster, B
  • Rosenstihl, M
  • Schneider, S
  • Talluto, V
  • Walther, T
  • Blochowicz, T
  • Stühn, B
  • Vogel, M
Type
Published Article
Journal
The Journal of Chemical Physics
Publisher
American Institute of Physics
Publication Date
Mar 21, 2014
Volume
140
Issue
11
Pages
114503–114503
Identifiers
DOI: 10.1063/1.4868003
PMID: 24655189
Source
Medline
License
Unknown

Abstract

We combine (2)H nuclear magnetic resonance (NMR), broadband dielectric spectroscopy (BDS), and triplet solvation dynamics (TSD) to investigate molecular dynamics in glass-forming mixtures of water and propylene glycol in very broad time and temperature ranges. All methods yield consistent results for the α process of the studied mixtures, which hardly depends on the composition and shows Vogel-Fulcher temperature dependence as well as Cole-Davidson spectral shape. The good agreement between BDS and TDS data reveals that preferential solvation of dye molecules in microheterogeneous mixtures does not play an important role. Below the glass transition temperature T(g), NMR and BDS studies reveal that the β process of the mixtures shows correlation times, which depend on the water concentration, but exhibit a common temperature dependence, obeying an Arrhenius law with an activation energy of E(a) = 0.54 eV, as previously reported for mixtures of water with various molecular species. Detailed comparison of NMR and BDS correlation functions for the β process unravels that the former decay faster and more stretched than the latter. Moreover, the present NMR data imply that propylene glycol participates in the β process and, hence, it is not a pure water process, and that the mechanism for molecular dynamics underlying the β process differs in mixtures of water with small and large molecules.

Report this publication

Statistics

Seen <100 times