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Structure, vibration, relaxations dans les systèmes désordonnés
(15) Production(s) de l'année 2023
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Surface properties of alkali silicate glasses: Influence of the modifiers 
Auteur(s): Zhang Z., Ispas S., Kob W.
(Article) Publié:
The Journal Of Chemical Physics, vol. 158 p.244504 (2023)
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On the medium-range order in silicate glass-formers: From standard two-body correlations to many-body correlations
Auteur(s): Kob W.
Conférence invité: 4th International Workshop on Challenges of MD simulations of Glasses and Amorphous Materials (Corning, US, 2023-07-13)
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Deformation and fracture of silicate glasses: New insights from atomistic simulations
Auteur(s): Kob W.
Conférence invité: GOMD 2023 (New Orleans, US, 2023-06-04)
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Properties of dentin, enamel and their junction, studied with Brillouin scattering and compared to Raman microscopy
Auteur(s): Desoutter Alban, Felbacq D., Gergely C., Varga B., Bonnet L., Etienne P., Vialla R., Cuisinier Frédéric, Salehi Hamideh, Rousseau E., Ruffle B.
(Article) Publié:
Archives Of Oral Biology, vol. 152 p.105733 (2023)
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Editorial: Nanocomposites with interfaces controlled by grafted or adsorbed polymers
Auteur(s): Holderer O., Genix A.-C., Kruteva M., Oberdisse J.
(Article) Publié:
Frontiers In Physics, vol. 10 p.1117549 (2023)
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How Tuning Interfaces Impacts the Dynamics and Structure of Polymer Nanocomposites Simultaneously
Auteur(s): Genix A.-C., Bocharova Vera, Carroll Bobby, Dieudonne-George P., Chauveau E., Sokolov Alexei, Oberdisse J.
(Article) Publié:
Acs Appl. Mater. Interfaces, vol. 15 p.7496-7510 (2023)
Texte intégral en Openaccess : 
Ref HAL: hal-04244949_v1
Ref Arxiv: 2310.14680
DOI: 10.1021/acsami.2c18083
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: Fundamental understanding of macroscopic properties of polymer nanocomposites (PNCs) remains difficult due to the complex interplay of microscopic dynamics and structure, namely interfacial layer relaxations and three-dimensional nanoparticle arrangements. The effect of surface modification by alkyl methoxysilanes at different grafting densities has been studied in PNCs made of poly(2-vinylpyridine) and spherical 20 nm silica nanoparticles (NPs). The segmental dynamics has been probed by broadband dielectric spectroscopy, and the filler structure by small-angle X-ray scattering and reverse Monte Carlo simulations. By combining the particle configurations with the interfacial layer properties, it is shown how surface modification tunes the attractive polymer-particle interactions: bare NPs slow down the polymer interfacial layer dynamics over a thickness of ca. 5 nm, while grafting screens these interactions. Our analysis of interparticle spacing and segmental dynamics provides unprecedented insight into the effect of surface modification on the main characteristics of PNCs: particle interactions and polymer interfacial layers.
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Influence of the Graft Length on Nanocomposite Structure and Interfacial Dynamics
Auteur(s): Genix A.-C., Bocharova Vera, Carroll Bobby, Dieudonne-George P., Chauveau E., Sokolov Alexei, Oberdisse J.
(Article) Publié:
Nanomaterials, vol. 13 p.748 (2023)
Texte intégral en Openaccess :
Ref HAL: hal-04244883_v1
Ref Arxiv: 2310.11201
DOI: 10.3390/nano13040748
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: Both the dispersion state of nanoparticles (NPs) within polymer nanocomposites (PNCs) and the dynamical state of the polymer altered by the presence of the NP/polymer interfaces have a strong impact on the macroscopic properties of PNCs. In particular, mechanical properties are strongly affected by percolation of hard phases, which may be NP networks, dynamically modified polymer regions, or combinations of both. In this article, the impact on dispersion and dynamics of surface modification of the NPs by short monomethoxysilanes with eight carbons in the alkyl part (C8) is studied. As a function of grafting density and particle content, polymer dynamics is followed by broadband dielectric spectroscopy and analyzed by an interfacial layer model, whereas the particle dispersion is investigated by small-angle X-ray scattering and analyzed by reverse Monte Carlo simulations. NP dispersions are found to be destabilized only at the highest grafting. The interfacial layer formalism allows the clear identification of the volume fraction of interfacial polymer, with its characteristic time. The strongest dynamical slow-down in the polymer is found for unmodified NPs, while grafting weakens this effect progressively. The combination of all three techniques enables a unique measurement of the true thickness of the interfacial layer, which is ca. 5 nm. Finally, the comparison between longer (C18) and shorter (C8) grafts provides unprecedented insight into the efficacy and tunability of surface modification. It is shown that C8-grafting allows for a more progressive tuning, which goes beyond a pure mass effect.
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