Mesoporous self-assembly

Time-resolved in situ Small Angle Neutron Scattering (SANS) investigations have provided direct experimental evidence for the initial steps in the formation of the SBA-15 mesoporous material, prepared using the non-ionic tri-block copolymer Pluronic 123 and TEOS as silica precursor. Upon time, three steps take place during the cooperative self-assembly of the Pluronic micelles and the silica species. First, the hydrolysis of TEOS is completed, without modifications of the Pluronic spherical micelles. Then, when silica species begin to interact with the micelles, a transformation from spherical to cylindrical micelles takes place before the precipitation of the ordered SBA-15 material. Lastly, the precipitation occurs and hybrid cylindrical micelles assemble into the two-dimensional hexagonal structure of SBA-15. 

In the near future, we wish to extend kinetics experiments to other synthesis of mesoporous materials, in order to determine how the self-assembly mechanisms are changing with respect to the type of synthesis. 

GENERATION OF MESOPOROUS CRYSTALLINE METAL OXIDE FILMS VIA EVAPORATION-INDUCED SELF-ASSEMBLY... 

Although the idea of applying mesoporous thin films of Ti02 (or other suitable oxides) prepared by self-assembly strategies in combination... 

Brezesinski, T. Groenewolt, M. Antonietti, M. Smarsly, B. 2006. Crystal-to-crystal phase transition in self-assembled mesoporous iron oxide films. Angew. Chem. Int. Ed. 45 781-784. 

Brezesinski, T. Smarsly, B. Iimura, K. Grosso, D. Boissiere, C. Amenitsch, H. Antonietti, M. Sanchez, C. 2005. Self-assembly and crystallization behavior of mesoporous, crystalline Hf02 thin films A model system for the generation of mesostructured transition-metal oxides. Small 1 889-898. 

Lancelle-Beltran, E. Prene, P Boscher, C. Belleville, R Buvat, P Lambert, S. Guillet, F. Boissiere, C. Grosso, D. Sanchez, C. 2006. Nanostructured hybrid solar cells based on self-assembled mesoporous titania thin films. Chem. Mater. 18 6152-6156. 

Malfatti, L. Falcaro, P Amenitsch, H. Caramori, S. Argazzi, R. Bignozzi, C. A. Enzo, S. Maggini, M. Innocenzi, P. 2006. Mesostructured self-assembled titania films for photovoltaic applications. Microporous Mesoporous Mater. 88 304-311. 

Ti-SBA-15 mesoporous, titanium-containing silica self-assembly-15 (with uniform, hexagonal, tubular channels) synthesized by using a triblock organic copolymer as a template... 

Recently, mesoporous aluminosilicates with strong acidity and high hydrothermal stability have been synthesized via self-assembly of aluminosilicate nanoclusters with templating micelles. The materials were found to contain both micro- and mesopores, and the pore walls consist of primary and secondary building units, which might be responsible for the acidity and stability (181). These materials were tested in isobutane/n-butene alkylation at 298 K, showing a similar time-on-stream behavior to that of zeolite BEA. No details of the product distribution were given. 

M. Mamak, N. Coombs, and G. Ozin, Self-assembling solid-oxide fuel cell materials mesoporous yttria-zirconia and metal—yttria-zirconia solid solutions, J. Am. CherrL Soc. 122, 8932-8939 (2000). 

These same general templating strategies are extended into the mesopore size regime with the use of self-assembled supramolecular arrays, a topic which has been extensively reviewed elsewhere. 

NANOPOROUS AND NANOSTRUCTURED CATALYSTS Self-Assembly AND Co-Assembly of Multiple Site-Isolated Catalytic Sites on Mesoporous Materials... 

Keywords Chalcogenide Germanium compound Mesoporous semiconductor Self-assembly Zintl compound... 

The ability of using mixed [Geg.nSin]" clusters as starting building blocks, which are soluble in ethylenediamine, allowed us to prepare mesoporous Ge/Si alloy semiconductors. These structures were synthesized as described above by the oxidative self-polymerization of mixed [Geg.nSin]" clusters with the assistance of self-assembled cationic surfactants (3). 

T0588 Pacific Northwest National Laboratory, Self-Assembled Mesoporous Support (SAMMS) Technology... 

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