Three dimensionally ordered macroporous

Sadakane, M., Asanuma, T., Kubo, J. et al. (2005) Facile procedure to prepare three-dimensionally ordered macroporous (3DOM) perovskite-type mixed metal oxides by colloidal crystal templating method, Chem. Mater. 17, 3546. 

The porous membrane templates described above do exhibit three-dimensionality, but with limited interconnectedness between the discrete tubelike structures. Porous structures with more integrated pore—solid architectures can be designed using templates assembled from discrete solid objects or su-pramolecular structures. One class of such structures are three-dimensionally ordered macroporous (or 3-DOM) solids, which are a class of inverse opal structures. The design of 3-DOM structures is based on the initial formation of a colloidal crystal composed of monodisperse polymer or silica spheres assembled in a close-packed arrangement. The interconnected void spaces of the template, 26 vol % for a face-centered-cubic array, are subsequently infiltrated with the desired material. 

THREE-DIMENSIONAL ORDERED MACROPOROUS HYBRID SILICA MATERIALS FUNCTIONALIZED WITH LACUNARY KEGGIN-TYPE POLYOXOMETALATES PREPARATION AND CHARACTERIZATION... 

Characterization of the XMo,-Si02 materials indicated that the synthesis produced three-dimensional ordered macroporous materials with highly dispersed polyoxometalates covalently incorporated within the wall structures. IR, UV/DRS, solid-state MAS NMR spectra confirmed that the polyoxometalates remained intact in the hybrid macroporous silica materials. At first, three solid XMOu-SiOj materials all exhibited two absorptions with maxima at ca. 200 and 260 nm, respectively (Figure 1). The former is stronger and... 

A templating method was presented to fabricate novel three-dimensional ordered macroporous silica materials ftinctionalized by polyoxometalates. Characterization of the products indicated that the starting XMo, remained intact regardless of the functionality of the polyanions, and their primary lacunry structures tended to get saturated. The future development of the method holds promise for the formation of advanced new materials with more novel properties, which can be applied in more wide fields. 

Ordered macroporous materials (OMMs) are a new family of porous materials that can be synthesized by using colloidal microspheies as the template. - The most unique characteristics of OMMs are their uniformly sized macropores arranged at micrometer length scale in three dimensions. Colloidal microspheres (latex polymer or silica) can self assemble into ordered arrays (synthetic opals) with a three-dimensional crystalline structure. The interstices in the colloidal crystals are infiltrated with a precursor material such as metal alkoxide. Upon removal of the template, a skeleton of the infiltrated material with a three-dimensionally ordered macroporous structure (inverse opals) is obtained. Because of the 30 periodicity of the materials, these structures have been extensively studied for photonic applications. In this paper, the synthesis and characterization of highly ordered macroporous materials with various compositions and functionalities (silica, organosilica, titana, titanosilicate, alumina) are presented. The application potential of OMMS in adsorption/separation is analyzed and discussed. 

A.A. Dong, Y.J. Wang, Y. Tang, Y.H. Zhang, N. Ren, and Z. Gao, Mechanically Stable Zeolite Monoliths with Three-dimensional Ordered Macropores by the Transformation of Mesoporous Silica Spheres. Adv. Mater., 2002, 14, 1506-1510. 

Lai, C.-Z., Fierke, M.A., Stein, A., and Buhlmann, P. 2007. Ion-selective electrodes with three-dimensionally ordered macroporous carbon as the solid contact. Analytical Chemistry 79, 4621-1626. 

Three-dimensionally ordered macroporous ceramic with high LR ion conductivity was prepared by colloidal crystal templating method using monodispersed polystyrene beads [12]. Monodispersed polystyrene beads with 3 pm diameter were dispersed in water and then filtrated by using a membrane filter under a small pressure difference. After this treatment, polystyrene beads were accumulated on the membrane filter with closed pack structure, as shown in Fig. 4.2. Then, the membrane consisting of accumulated polystyrene beads was removed from the membrane filter and put on a glass substrate. After drying at room temperature, the... 

Fig. 4.3 Scanning electron micrographs of surface and cross section for prepared three-dimensionally ordered macroporous Li jLa jjTiOj...

Fig. 4.8 Preparation process of three-dimensionally ordered macroporous silica membrane...

Fig. 4.9 Photograph of composite membrane between 2-acrylamido-2-methyl propane sulfonic acid and three-dimensionally ordered macroporous silica...

Table 4.1 Proton conductivity and methanol permeability of the composite membrane with three-dimensionally ordered macroporous silica matrix. Measurement temperature 30°C, Methanol concentration 10 mol dm ...

The membrane shown in Fig. 4.10 was prepared using this three-dimensionally ordered macroporous polyimide obtained according to the above process with AMPS polymer. The proton conductivity and methanol permeability of the composite membrane are summarized in Table 4.2. The proton conductivity of the composite membrane was higher than that of Nafion and the methanol permeability of the composite membrane was slightly lower than that of Nafion . Both tendencies are good for membrane for direct methanol fuel cell. In this way, three-dimensionally ordered macroporous materials are suitable for matrix of soft proton conductive polymer with higher proton conductivity. 

Fig. 4.11 Three-dimensionally ordered macroporous carbon by using monodispersed silica template and polyimide...

Fig. 4.14 Scanning electron micrograph of three-dimensionally ordered macroporous carbon with controlled pore size distribution...

Figure 4.15 shows the discharge and charge curves of the prepared three-dimensionally ordered macroporous carbon with controlled meso pores in Et NBPy PC at various currents. From the results, the electric capacity of this carbon was estimated to be 90 Fg . 

Such a structure provides highly uniform porous nature. This is the most important point. For example, the uniform reaction may occur in all the pores. A higher mechanical strength may be realized from ordered stmcture. Especially, two-dimensional electrochemical reactions are strongly enhanced by using three-dimensionally ordered porous materials, as mentioned above. In other words, two-dimensional electrochemical reactions are converted to pseudo three-dimensional ones. This procedure is useful for practical applications. Presently, preparation of three-dimensionally ordered macroporous materials is not so easy due to low mechanical strength and the presence of minor defects. More extensive research will be carried out in the near future. 

Stein A, Schroden RC (2001) Colloidal crystal templating of three-dimensionally ordered macroporous solids materials for photonics and beyond. Cnrr Opin Solid State Mater Sci 5 553... 

Sen T, Tiddy GJT, Casci JL, Anderson MW (2004) Synthesis and characterization of hierarchically ordered porous silica materials. Chem Mater 16 2044 Deng Y, Liu C, Yu T, Liu F, Zhang F, Wan Y, Zhang L, Wang C, Tu B, Webley PA, Wang H, Zhao D (2007) Facile synthesis of hierarchically porous carbons from dual colloidal crystal/block copolymer template approach. Chem Mater 19 3271 Luo Q, Li L, Yang B, Zhao D (2000) Three-dimensional ordered macroporous structures with mesoporous silica walls. Chem Lett 29 378... 

In order to produce a three-dimensionally ordered macroporous structure, the metal precursor solution should fulfil the following criteria (1) Sufficient metal should be present in the voids to form a macroporous wall, and the metal concentration should therefore be high. (2) Reactivity of the metal precursor should be mild so that it can infiltrate the voids. If the metal precursor reacts with a functional group on the surface of the template or moisture in the air before it infiltrates the voids, an ordered porous structure cannot be obtained. (3) The metal precursor should be solidified in the voids before the template is removed and the produced... 

Figure 3.7 Colloidal crystal templating method to produce three-dimensionally ordered macroporous materials...

Three-dimensionally ordered macroporous crystalline Ti02 could be obtained by using titanium alkoxides as a metal source. Various titanium alkoxides [Ti(OEt)4, Ti(0 Pr)4, Ti(OBu)4] can be used in alcoholic solutions or neat.f " After the titanium alkoxides have infiltrated the voids of the template, they can be solidified by drying in air (sometimes heated at ca 50 °C) by a sol-gel process. Another titanium source, ammonium lactate titanium dihydroxide, can be used. A gaseous Ti source, TiCE, can be used. Gaseous TiCU was deposited on a SiOi template, and then TiCU was hydrolysed with vaporous H2O. This two-step deposition of Ti02 on the template was repeated to deposit Ti02 in the voids of the template. ... 

Three-dimensionally ordered macroporous crystalline V2O5 could be obtained by using vanadium alkoxide V0(0 Pr)3 as a metal source. 

Figure 4.16 SEM images of porous carbons prepared using hard template consisting of large polymer colloids (450 nm diameter) and small silica colloids. The particle size of silica colloids used as template for the small spherical pores is (a) 70-100 nm and (b) 40-50 nm. 1 Reprinted with permission from S.W. Woo, K. Dokko, K. Sasajima, T. Takei and K. Kanamura, Three-dimensionally ordered macroporous carbons having walls composed of hollow mesosized spheres. Chem. Commun., 4099—4101. Copyright (2006) Royal Society of Chemistry...

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