Thermodynamic Scaling of the Dynamics of a Strongly Hydrogen-Bonded Glass-Former

We probe the temperature- and pressure-dependent specific volume ( v ) and dipolar dynamics of the amorphous phase (in both the supercooled liquid and glass states) of the ternidazole drug (TDZ). Three molecular dynamic processes are identified by means of dielectric spectroscopy, namely the α relax...

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Bibliographic Details
Published in:Scientific reports 2017-05, Vol.7 (1), p.1346-11, Article 1346
Main Authors: Romanini, Michela, Barrio, María, Macovez, Roberto, Ruiz-Martin, María D., Capaccioli, Simone, Tamarit, Josep Ll
Format: Article
Language:English
Subjects:
639/766/119/1002
639/766/530/951
Aplicacions
Density dependence
Dinàmica
Dynamics
Física
Humanities and Social Sciences
Hydrogen
Hydrogen bonding
multidisciplinary
Pressure
Propanol
Scaling
Science
Science (multidisciplinary)
Spectroscopy
Spectrum analysis
Temperature effects
Termodinàmica
Ternidazole
Thermodynamics
Àrees temàtiques de la UPC
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Summary:We probe the temperature- and pressure-dependent specific volume ( v ) and dipolar dynamics of the amorphous phase (in both the supercooled liquid and glass states) of the ternidazole drug (TDZ). Three molecular dynamic processes are identified by means of dielectric spectroscopy, namely the α relaxation, which vitrifies at the glass transition, a Johari-Goldstein β JG relaxation, and an intramolecular process associated with the relaxation motion of the propanol chain of the TDZ molecule. The lineshapes of dielectric spectra characterized by the same relaxation time (isochronal spectra) are virtually identical, within the studied temperature and pressure ranges, so that the time-temperature-pressure superposition principle holds for TDZ. The α and β JG relaxation times fulfil the density-dependent thermodynamic scaling: master curves result when they are plotted against the thermodynamic quantity Tv γ , with thermodynamic exponent γ approximately equal to 2. These results show that the dynamics of TDZ, a system characterized by strong hydrogen bonding, is characterized by an isomorphism similar to that of van-der-Waals systems. The low value of γ can be rationalized in terms of the relatively weak density-dependence of the dynamics of hydrogen-bonded systems.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-017-01464-2