3DOM materials

Recently, the LbL technique has been extended from conventional nonporous substrates to macroporous substrates, such as 3DOM materials [58,59], macroporous membranes [60-63], and porous calcium carbonate microparticles [64,65], to prepare porous PE-based materials. LbL-assembly of polyelectrolytes can also be performed on the surface of MS particles preloaded with enzymes [66,67] or small molecule drugs [68], and, under appropriate solution conditions, within the pores of MS particles to generate polymer-based nanoporous spheres following removal of the silica template [69]. 

Because macroporous materials have 3D periodicity on a length scale comparable to the wavelength of visible light, 3DOM materials have potential use as photonic crystals. Other potential applications include catalysts, bioglasses, sensors, and substrates for surface-enhanced Raman scattering spectroscopy (SERS). ... 

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. 

In the case of a potassium peroxosulfate or 2,2 -azobis(2-methylpropionami-dine) dihydrochloride initiator, and [SOJ or Cl may remain in the 3DOM materials even after calcination (Table 6.2) [63,73]. 

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. 

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. 

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. 

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