3DOM structure

Other attempts follow the dual micellular templating approach involving a combination of block copolymers, surfactants, and alcohols [208]. The colloidal templating method produces three-dimensionally ordered macrostructures (3DOM-structures) [208]. However, even for the colloidal templating, the routes include besides the formation of the three-dimensionally arranged colloidal crystal always a second... 

A well-ordered 3DOM structure was observed by SEM for all samples (Figure 6.6). Well-ordered air spheres and interconnected walls create an inverse opal structure in three dimensions, and the next layer is clearly visible. Large fiactions (more than 95% of the particles by SEM images) of all the 3DOM materials were highly ordered porous structures over a range of tens of micrometers. 

Porosity was calculated by the amount of intrusion Hg in the macropores. The calculated porosity of 3DOM-PPS-268 was 80%, which is close to the theoretical value (74%) of porosity of inverse opals. This result indicates that samples made by our method have the desired 3DOM structure quantitatively. 

Crystallite sizes estimated from XRD were 26-36 nm, which are similar to wall thickness of the 3DOM structure (Figure 6.9b). Further heating increases crystallite size and overheating (about 800 °C) collapses the 3DOM structure. 

Here we summarized methods to produce 3DOM perovskite mixed metal oxides with pore sizes in the submicrometer range. There are many methods to produce 3DOM perovskites with many kinds of metals. The 3DOM structure ensures access of molecules and ions to the surfe.ce of perovskite mixed metal oxides, and many advantages of the 3DOM structure have been reported. It is expected that the introduction of 3DOM structure is one important way to enhance the performance of perovskite mixed oxides. 

Because of the attractive physicochemical properties and potential applications in catalysis, biotechnology, adsorption, and separation, fabrication of hierarchically porous (macro/mesoporous) materials, especially for the three-dimensional ordered macro/ mesoporous (3DOM) materials, has been a focus in the research on materials science and engineering in recent years [99,199,200], By using close-packed arrays of monodisperse spheres, such as polystyrene (PS), poly(methyl methacrylate) (PMMA), and silica as template, metals [201,202], metal oxides [203-208], metal chalcogenides [209], silica [204,210,211], carbon [212,213], polymers [214,215], and hydroxyapatite [216] with 3DOM structures have been generated. 

Figure 16.6 Hammett plot for the oxidation of a series of substituted phenylurea herbicides by 3DOM. The linear regression line is given in Eq. 16-19. The compound names and structures as well as the corresponding crj, aj (= ),...

DOM materials are prepared using colloidal crystal templates [2-8]. The colloidal crystal (opal structure) templates consist of monodispersed spheres with face-centered closed (fee) packing. When 3D network of voids in colloidal crystals is filled by targeted materials and subsequentiy the colloidal crystals are removed, a replica of the colloidal crystal (inverse opal structure) is produced (Figure 6.2). 

Structure of 3DOM Materials (Inverse Opal Structures)... 

Rhombic dodecahedron Figure 6.3 Structures of crystalline 3DOM materials. 

Sadakane, M., Takahashi, C, Kato, N., Ogihara, H., Nodasaka, Y., Doi, Y., Hinatsu, Y., and Ueda, W. (2007) Three-dimensionally ordered macroporous (3DOM) materials of spinel-type mixed iron oxides. Synthesis, structural characterization, and formation mechanism of inverse opals with a skeleton structure. Bull. Chem. Soc. Jpn., 80, 677-685. 

Recently, several three-dimensionally ordered macroporous (3DOM) solids have been investigated as soot combustion catalysts, some of them based on perovskite structures, and this approach could be a solution for the low siuface... 

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