Laboratoire Charles Coulomb UMR 5221 CNRS/UM2 (L2C)


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Structuring of Self-Assembled Hybrid Silicas : Mechanistic Studies

par Sébastien LAYSSAC - publié le , mis à jour le

Involved researchers : J-L. Bantignies, Ph. Dieudonné, C. Blanc, J-L. Sauvajol
(Collaboration M. Wong Chi Man - ENSCM Montpellier, G. Creff - Synchrotron Soleil)

This activity has been devoted to the understanding of the self-assembling mechanisms of organic-inorganic hybrid silicas obtained via sol-gel route. The molecular precursors consist of an inorganic substructure with triethoxysilyl groups associated to an organic substructure which provides the self-organization properties. The competition between covalent and non covalent interactions during the self-organization process has been especially investigated. The influence of self-assembly via intermolecular H-bonds during the synthesis of the material in solution is followed by infrared spectroscopy. An in situ experimental study which combines optical microscopy, light scattering and infrared spectroscopy gives a better insight into the self-assembling kinetics of the precursors. We propose a structuring model in solution dominated by activation barriers governed by H-bonds (figure 1). The structure of the hybrid materials in solid phase are determined from structural studies based on X-Ray diffraction. The investigation under pressure of the hybrid materials obtained after heating and freeze-drying shows that both the short order arrangement (H-bonds, polycondensation rate) and the mesoscopic structure strongly depend on this step.

Structuring model of hybrid material (HM) in solution and image of HM in solution - © L2C

- J-L. Bantignies et al. Insights into the Self-Directed Structuring of Hybrid Organic-Inorganic Silicas through Infrared studies. J. Phys. Chem. B., 110, 15797-15802 (2006)
- Philippe Dieudonne et al. In situ X-Ray Measurements to probe a New Solid State Polycondensation Mechanism for the Design of Supramolecular Organo-Bridged Silsequioxanes. Small, 5, 503-510 (2009)