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- H bond spring behaviour in hybrid silica under pressure hal link

Auteur(s): Le Parc R., Freitas Vânia, Creff G., Wong Chi Man M., Cattoën Xavier, Hermet P., Ferreira Rute A.S., Carlos Luis D., Bartlett John R., Bantignies J.-L.

Conference: 11eme Forum de technologie des Hautes Pressions (Sète, FR, 2018-10-01)


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Résumé:

Bridged silsesquioxane nanomaterials exhibit original mechanical properties thanks to the association of non-covalent and covalent interactions. Thanks to in situ high pressure spectroscopic studies, achieved in diamond anvil cells, the mechanical behavior of these materials was followed as a function of pressure. Figure 1: Schematic representation of bottom-up structuring in organic-inorganic hybrid silica through self-assembling process Vibrational studies on organic models coupled to ab-initio simulations show that H bond response to pressure is strengthening. In hybrid materials the H bond shows its ability to absorb the mechanical constrains by the modulation of H bond interactions. We thus show that the rigidity yielded by the inorganic polymerization is counterbalanced by the presence of the intermolecular H bond network. The hybrid materials have therefore a reversible behavior, thanks to h bonds behaving as molecular springs. For higher pressure ranges inorganic network start to be strongly impacted in a dominant way so that an irreversible loss of long range order within the organic network is observed.In a second time, the influence of the nature of the organic substructure (thiourea versus urea link, aryl versus aliphatic core) on this spring behavior is discussed.