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2008
ACL
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I.V.Melnyk, Y.L.Zub, E.Véron, D.Massiot, T.Cacciagarra, B.Alonso, 'Spray-dried mesoporous silica microspheres with adjustable textures and pore surfaces homogenously covered by accessible thiol functions', J. Mater. Chem. 18 1368-1382 (2008) doi:10.1039/b717133a
Micrometric mesoporous spheres with textures possessing a relative high degree of ordering and incorporating up to 0.1 thiol function per siloxane unit have been synthesised through solgel, self-assembly and spray-drying processes. The sol preparation was optimised as a function of the final properties: morphology, texture, and proportion of thiol functions. A twosteps synthesis allows in positioning these functions at the pore surface as proven in particular by 1H solid state NMR. From Ag+ sorption experiments, we have also shown that the thiol functions are also homogenously distributed in the sphere’s volume and fully accessible to external chemical species. So these materials could be used for environment remediation or metallic nano-particle syntheses. In order to increase the stability and applicability of the materials, different post-synthesis treatments have been studied. A thermal treatment under mild conditions is enough to preserve most of the properties. From the hydrothermal treatments tested, the use of ammonia is shown to be quite interesting for the modulation of the properties. In particular, hierarchical porosities and high specific surface areas have been created. The high degree of ordering observed for the smaller pores is accompanied by a reordering of the surfactant polar head groups as deducted from 14N NMR. Lastly, the synthesis can be extended under some conditions to other functions or to higher proportions of thiol functions (up to 0.2).
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