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Macroporous morphology of nanostructured Layered Double Hydroxides
|Vanessa Prevot , Erwan Géraud , Claude Forano , Fabrice Leroux|
BLAISE PASCAL UNIVERSITY, 24 Av des landais, Aubiere 63177, France
Recently, sacrificial template methods have been shown to offer an efficient way for the fabrication of nanostructured materials. Among all possible templates, self assembled colloidal crystals also called synthetic opals can be used for creating three dimensionally ordered macroporous structures with interconnected macropores.
In this work by using this strategy, we successfully synthesized three dimensionally macroporous Layered Double Hydroxides (LDH), a class of synthetic anionic layered clays, from successive impregnation cycles. Then metal salts precursors impregnated on polystyrene sphere closed packed array is converted by coprecipitation into the solid state LDH structure around the beads. The macroporosity is subsequently liberated by elimination of polymer beads either by dissolution or calcinations. The nanostructured LDH particles obtained display both macro and mesoporosity. The synthetic process has been followed by in situ PXRD, electronic microspocpy and 27Al NMR experiments. In varying the nature of the precursors, it is possible to change the composition of the as-prepared macroporous materials, which maintain the own structural and anionic exchange properties of LDH. Nevertheless, the pH conditions and the peculiar crystal growth of some LDH compositions limit the extension to all the compositions, since the precipitation are not under control. All these points will be discussed as well as the thermal decomposition of various macroporous LDH into macroporous mixed oxides.
Presentation: Oral at E-MRS Fall Meeting 2007, Symposium A, by Vanessa Prevot
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-16 13:51 Revised: 2009-06-07 00:44