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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Delbreilh, Laurent
University of Rouen
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (19/19 displayed)
- 2024Highlighting the interdependence between volumetric contribution of fragility and cooperativity for polymeric segmental relaxationcitations
- 2023Effect of physical and chemical ageing on barrier properties of epoxy coatingcitations
- 2023Effect of Chemical Composition on Molecular Mobility and Phase Coupling in Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) with Different Comonomer Contentscitations
- 2023Post‐curing and structural relaxation of epoxy networks during early stages of aging for civil engineering applicationscitations
- 2022Segmental Relaxation Dynamics in Amorphous Polylactide Exposed to UV Lightcitations
- 2022Macromolecular Mobility Changes Induced by Thermal Aging of Epoxy‐amine Polymer Networkscitations
- 2021Water-Induced Breaking of Interfacial Cohesiveness in a Poly(lactic acid)/Miscanthus Fibers Biocompositecitations
- 2019Determination of the equilibrium enthalpy of melting of two-phase semi-crystalline polymers by fast scanning calorimetrycitations
- 2019Polymer additive manufacturing of ABS structure: Influence of printing direction on mechanical propertiescitations
- 2019Cooperativity Scaling and Free Volume in Plasticized Polylactidecitations
- 2018Relaxation dynamics in plasticized polylactidecitations
- 2016Rock permittivity characterization and application of electromagnetic mixing models for density/compactness assessment of HMA by means of step‐frequency radarcitations
- 2016Molecular Relaxations in Supercooled Liquid and Glassy States of Amorphous Quinidine: Dielectric Spectroscopy and Density Functional Theory Approachescitations
- 2015Molecular mobility and physical ageing of plasticized poly(lactide)citations
- 2015Segmental mobility and glass transition of poly(ethylene-vinyl acetate) copolymers : Is there a continuum in the dynamic glass transitions from PVAc to PE?citations
- 2013Development of poly(isobutylene-co-isoprene)/reduced graphene oxide nanocomposites for barrier, dielectric and sensingapplicationscitations
- 2012Study of the cooperativity at the glass transition temperature in PC/PMMA multilayered films: Influence of thickness reduction from macro- to nanoscalecitations
- 2007Study of poly(bisphenol A carbonate) relaxation kinetics at the glass transition temperaturecitations
- 2005Effect of macromolecular orientation on the structural relaxation mechanisms of poly(ethylene terephthalate)citations
Places of action
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article
Molecular Relaxations in Supercooled Liquid and Glassy States of Amorphous Quinidine: Dielectric Spectroscopy and Density Functional Theory Approaches
Abstract
In this article, we conduct a comprehensive molecular relaxation study of amorphous Quinidine above and below the glass-transition temperature (Tg) through broadband dielectric relaxation spectroscopy (BDS) experiments and theoretical density functional theory (DFT) calculations, as one major issue with the amorphous state of pharmaceuticals is life expectancy. These techniques enabled us to determine what kind of molecular motions are responsible, or not, for the devitrification of Quinidine. Parameters describing the complex molecular dynamics of amorphous Quinidine, such as Tg, the width of the α relaxation (βKWW), the temperature dependence of α-relaxation times (τα), the fragility index (m), and the apparent activation energy of secondary γ relaxation (Ea-γ), were characterized. Above Tg (> 60 °C), a medium degree of nonexponentiality (βKWW = 0.5) was evidenced. An intermediate value of the fragility index (m = 86) enabled us to consider Quinidine as a glass former of medium fragility. Below Tg (< 60 °C), one well-defined secondary γ relaxation, with an apparent activation energy of Ea-γ = 53.8 kJ/mol, was reported. From theoretical DFT calculations, we identified the most reactive part of Quinidine moieties through exploration of the potential energy surface. We evidenced that the clearly visible γ process has an intramolecular origin coming from the rotation of the CH(OH)C9H14N end group. An excess wing observed in amorphous Quinidine was found to be an unresolved Johari–Goldstein relaxation. These studies were supplemented by sub-Tg experimental evaluations of the life expectancy of amorphous Quinidine by X-ray powder diffraction and differential scanning calorimetry. We show that the difference between Tg and the onset temperature for crystallization, Tc, which is 30 K, is sufficiently large to avoid recrystallization of amorphous Quinidine during 16 months of storage under ambient conditions.