Design of Transition Metal Oxide and Hybrid Mesoporous Materials
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Design of Transition Metal Oxide and Hybrid Mesoporous Materials Clément Sanchez,* Eduardo L. Crepaldi, Anne Bouchara, Florence Cagnol, David Grosso, Galo J. de A. A. Soler-Illia Laboratoire de Chimie de la Matière Condensée, Université Pierre et Marie Curie – CNRS 4 place Jussieu, 75252, Paris CEDEX 05, France. E-mail: [email protected].
ABSTRACT Mesostructured transition metal (Ti, Zr, V, Al and Ce-Zr) oxide-based hybrid thin films, templated by poly(ethylene oxide)-based surfactants or block copolymers, have been prepared reproducibly, displaying 2D-hexagonal (p6m) or 2D-centred rectangular (c2m) structure. By carefully adjusting the variables involved it is possible to combine both high organisation and excellent optical quality. TiO2 and ZrO2-based materials show thermal stability up to 400-550 °C. The elimination of the template can be conducted efficiently and gives rise to high surface area mesoporous films. For the other metal oxide hybrids the inorganic framework is much more fragile, and requires a precise sequence of post-treatments to be stabilised. In addition, original and homogeneous macrotextures shaped with coral-like, helical or macroporous sieves morphologies have been obtained following a nanotectonic approach based on the template-directed assembly by poly-γ-benzyl-L-glutamate (PBLG) of organically functionalised CeO2 crystalline nanoparticles.
INTRODUCTION Hybrid organic-inorganic nanocomposites are extremely versatile in composition, processing, and optical and mechanical properties [1]. One of the most striking examples of those composites are the mesostructured hybrid networks, which are precursors to mesoporous solids [2]. The construction of these networks can be tailored by the adequate use of sol-gel methods, tuning the hydrolysis-condensation of the metallic cations with the self-assembly of the organic counterparts. These materials can be processed as powders, films or fibers, displaying a great mesostructural variety [2, 3]. Indeed, the evaporation-induced self-assembly (EISA) process [4] represents an efficient way for the design of such hybrids. By the adequate set up of the parameters involved one can tune the self assembly of the amphiphilic molecules in supramolecular templates, together with the condensation of the inorganic moieties around them. Recently, we reported the preparation and characterisation of titania [5], zirconia [6], alumina [7] and vanadia [8] mesoporous films by EISA, using poly(ethylene oxide)-based nonionic surfactants or block copolymers as structure directing agents. Here, we rationalise the different results obtained for the various systems, focused on the role of the metal cation chemical behaviour in the formation and stabilisation of the mesophases. We also extended this method for the formation of cerium oxide and zirconium-cerium mixed oxide based systems. The supramolecular template method allows one to texture materials in the mesoscale (dimensions up to 200-300 Å). Macrotexturation requires larger templates, such as latex particles. Here, we
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