Thin mesostructured

Mesostructures prepared through S°I° or N°F pathways have either wormhole6,7 or lamellar framework structures8,9. The wormhole structures possess a three-dimensional channel structure. Moreover, the framework domain size can be made very small (e.g., 20-200 nm), which introduces an intraparticle textural porosity that is complementary to the framework porosity. The combination of wormhole framework pores and textural pores can greatly facilitate access to catalytic centers in the framework walls. Lamellar frameworks, on the other hand, can be folded into vesicular particles with very thin mesostructured shells and hollow cores. These hierarchical structures also can facilitate access to reactive catalytic centers in the framework walls by minimizing the diffusion path length. 

Electrodeposition or pulsed-laser deposition techniques are additional possibilities for forming thin mesostructured films. These techniques have mainly been applied to non-silica mesostructured films such as niobia or platinum, but also hexagonally oriented mesoporous silica films were prepared by pulsed-laser deposition. ... 

Vanden Bout D A, Kerimo J, Higgins D A and Barbara P F 1997 Near-field optical studies of thin-film mesostructured organic materials Acc. Chem. Res. 30 204-12... 

Figure 4.18 TEM images showing the mesostructures of Ti02 species dispersed in Si02 transparent thin films with (a) a hexagonal ordered pore arrangement and (b, c) cubic symmet7. Reproduced from [247] (2003) with permission from Elsevier.

Bose, F., Ayral, A., Albouy, P.A., Datas, L. and Guizard, C. (2004) Mesostructure of anatase thin films prepared by mesophase templating. Chemistry of Materials, 16 (11), 2208-2214. 

Figure 9.6. Illustration of the crystallization process (the layered stacks symbolize the nanocrystals) and shrinkage of the mesostructure in thin films upon heat treatment. 

Alberius, P. C. A. Frindell, K. L. Hayward, R. C. Kramer, E. J. Stucky, G. D. Chmelka, B. F. 2002. General predictive syntheses of cubic, hexagonal, and lamellar silica and titania mesostructured thin films. Chem. Mater. 14 3284-3294. 

Grosso, D. Soler-Illia, G. Crepaldi, E. L. Cagnol, F. Sinturel, C. Bourgeois, A. Brunet-Bruneau, A. Amenitsch, H. Albouy, P. A. Sanchez, C. 2003. Highly porous Ti02 anatase optical thin films with cubic mesostructure stabilized at 700 degrees C. Chem. Mater. 15 4562 570. 

Brezesinski, T. Fischer, A. Iimura, K. Sanchez, C. Grosso, D. Antonietti, M. Smarsly, B. M. 2006. Generation of self-assembled 3D mesostructured Sn02 thin films with highly crystalline frameworks. Adv. Funct. Mater. 16 1433-1440. 

Etienne, M. Quach, A. Grosso, D. Nicole, L. Sanchez, C. Walcarius, A. 2007. Molecular transport into mesostructured silica thin films Electrochemical monitoring and comparison between p6m, P6(3)/mmc, and Pm3n structures. Chem. Mater. 19 844-856. 

The thin film of silica-surfactant mesostructured material was prepared by the reactions of TMOS and C18TAC, as reported previously[3]. The film was calcined in air to prepare nanoporous silica films. The adsorption of the dye onto the nanoporous silica film was conducted either by immersing the calcined film into an ethanol solution of the dye or casting the solution onto the film. 

By spin coating the mixture containing the prehydrolyzed TMOS and a 0.2 M aqueous solution of C18TAC (pH=2, at the molar ratio of TMOS C18TAC=9.2.T), a transparent thin film formed on the substrate. The X-ray diffraction pattern of the film (Figure 1a) showed a sharp diffraction peak with the d value of 4.6 nm, which accompanied the 2nd order reflection. In order to remove the surfactants from the substrate to obtain porous silica films, the as coated film of the silica-surfactant mesostructured material was calcined in air at 450 °C. Sharp diffraction peak was observed in the XRD pattern of the calcined film... 

Nicole L Boissiere C Grosso D Quach A Sanchez C, Mesostructured hybrid organic-inorganic thin films, J. Mater. Chem., 2005, 15, 3598-3627. 

Figure 5.3.9 (A) Simplified geometric model [46, 89] for the preparation of industrial Cu/ZnO catalysts comprising subsequent meso- and nanostructuring of the material from [56], In a first micro structure directing step (mesostructuring), the Cu,Zn coprecipitate crystallizes in the form of thin needles of the zincian malachite precursor, (Cu,Zn)2(0H)C03. In a second step, the individual needles are decomposed and demix into CuO and ZnO. The effectiveness of this nanostructuring step depends critically on a high Zn content in the precursor, which in zincian malachite is limited to Cu Zn ca. 70 30 due to solid-state chemical constraints [75]. Finally, interdispersed CuO/ZnO is reduced to yield active Cu/ZnO. (B) Chemical memory Dependence of catalytic activity in methanol synthesis on the conditions of the coprecipitation and aging steps, from [85].

Crepaldi, E.L., G. Soler-Illia, D. Grosso, F. Cagnol, F. Ribot and C. Sanchez (2003). Controlled formation of highly organized mesoporous titania thin films From mesostructured hybrids to mesoporous nanoanatase Ti02. Journal of the American Chemical Society, 125(32),... 

Bose, F., Synthesis and characterization of anatase-based mesostructured thin layers and membranes with photocatalytic properties, Ph.D. dissertation. University MontpeUier B, Montpellier, France, 2004. 

We were interested in the potential of the syndiesized diblock copolymers as templates in the synthesis of mesostructured silicate materials. Our focus was the pr aration of mesoordered thin films via the evaporation-induced self-assembly process [7]. For this purpose PDMS-b-PEO were mixed with a precursor solution containing the network-building species, and films were produced via a dip-coating procedure [8]. XRD diffraction patterns confirmed the formation of lamellar materials which were stable upon calcination at 430 °C/3 h. 

Several synthetic strategies to control the sizes of mesoporous nanoparticles have been reported. Lu[272] reported a rapid, aerosol-based process for synthesizing solid, well ordered spherical particles with stable pore mesostructures of hexagonal and cubic topology, as well as layered (vesicular) structures. This method relies on evaporation-induced interfacial self-assembly confined to spherical aerosol droplets. This simple, generalizable process can be modified for the formation of ordered mesostructured thin films. 

PC.A. Alberius, K.L. Frindell, R.C. Hayward, E.J. Kramer, G.D. Stucky, and B.F. Chmelka, General Predictive Syntheses of Cubic, Hexagonal, and Lamellar Silica and Titania Mesostructured Thin Films. Chem. Mater., 2002, 14, 3284—3294. 

In this technique, favorable substrate-solution or air-solution interfacial interactions are used to drive the self-assembly and formation of a thin film of the mesostructured material. The precursor solutions used... 

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