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Dynamique et rhéologie des fluides complexes (gels, polymères, mousses, colloïdes)
(24) Production(s) de l'année 2020
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New interaction potentials for borate glasses with mixed network formers 
Auteur(s): Sundararaman Siddharth, Huang L., Ispas S., Kob W.
(Article) Publié:
The Journal Of Chemical Physics, vol. 152 p.104501 (2020)
Texte intégral en Openaccess : 
Ref HAL: hal-02563181_v1
DOI: 10.1063/1.5142605
WoS: 000519911600001
Exporter : BibTex | endNote
Résumé: We adapt and apply a recently developed optimization scheme used to obtain effective potentialsfor aluminosilicate glasses to include the network former boron into the interaction parameter set.As input data for the optimization, we used the radial distribution functions of the liquid at hightemperature generated by ab initio molecular dynamics simulations, and density, coordination andelastic modulus of glass at room temperature from experiments. The new interaction potentials areshown to reproduce reliably the structure, coordination and mechanical properties over a widerange of compositions for binary alkali borates. Furthermore, the transferability of these newinteraction parameters allows mixing to reliably reproduce properties of various boroaluminateand borosilicate glasses.
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Determining the Mesh Size of Polymer Solutions via the Pore Size Distribution
Auteur(s): Sorichetti V., Hugouvieux Virginie, Kob W.
(Article) Publié:
Macromolecules, vol. 53 p.2568-2581 (2020)
Texte intégral en Openaccess :
Ref HAL: hal-02540128_v1
Ref Arxiv: 1908.01484
DOI: 10.1021/acs.macromol.9b02166
WoS: 000526399500029
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
1 Citation
Résumé: In order to determine in polymeric systems the geometrical mesh size ξ, we simulate a solution of coarse-grained polymers with densities ranging from the dilute to the concentrated regime and for different chain lengths. We determine the monomer density fluctuation correlation length ξc from the monomer structure factor as well as the radial distribution function, showing that the identification ξ = ξc is not justified outside of the semidilute regime. In order to better characterize ξ, we compute the pore size distribution (PSD) following two different definitions, one by Torquato et al. and one by Gubbins et al. We find that the mean values of the two distributions, ⟨r⟩T and ⟨r⟩G, display the behavior predicted for ξ by scaling theory, and argue that ξ can be identified with either one of these quantities. This identification allows to interpret the PSD as the distribution of mesh sizes, a quantity which conventional methods cannot access. Finally, we show that it is possible to map a polymer solution on a system of hard or overlapping spheres, for which Torquato’s PSD can be computed analytically and reproduces accurately the PSD of the solution. We give an expression that allows ⟨r⟩T to be estimated with high accuracy in the semidilute regime by knowing only the radius of gyration and the density of the polymers.
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Microscopic precursors of failure in soft matter
Auteur(s): Cipelletti L., Martens Kirsten, Ramos L.
(Article) Publié:
Soft Matter, vol. 16 p.82-93 (2020)
Texte intégral en Openaccess :
Ref HAL: hal-02634755_v1
Ref Arxiv: 1909.11961
DOI: 10.1039/C9SM01730E
WoS: 000503491000005
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
Résumé: The mechanical properties of soft matter are of great importance in countless applications, in addition of being an active field of academic research. Given the relative ease with which soft materials can be deformed, their non-linear behavior is of particular relevance. Large loads eventually result in material failure. In this Perspective article, we discuss recent work aiming at detecting precursors of failure by scrutinizing the microscopic structure and dynamics of soft systems under various conditions of loading. In particular, we show that the microscopic dynamics is a powerful indicator of the ultimate fate of soft materials, capable of unveiling precursors of failure up to thousands of seconds before any macroscopic sign of weakening.
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