Nanocomposite materials mesoporous preparation

Mesoporous pore s functionalized materials have been eonsidered as ideal nanoreactors for the deposition or growth of various guest moleeules. Among them, the introduction of metallic nanoparticles constitutes a judicious choice for preparing nanocomposite materials able to display catalytic properties that can find application as catalytic filters (Scheme 12.4). ... 

In addition, nanocomposite materials of silica-based mesoporous molecular sieve, MCM-41 with conducting COPANI ofpolyfmethyl aniline) inside the channels (COPANI/S-MCM-41) have been also prepared and their nanocomposite formations have been confirmed through N -adsorption isotherm, SEM and TEM measurement (see Figure 14.18a-d). However, the suspension of COPANI/S-MCM-41 shows decreased ER properties than those of PANI/MCM-41 or PANI alone, because the COPANI/S-MCM-41 has lower conductivity (see Figure 14.18e) [100]. 

Mesoporous zirconia is a particulate oxide with properties for several applications such as catalyst or catalyst support [1, 2] and nanocomposite materials (Chap. 25) [3, 4]. Moreover, zirconia nanoparticles are subject of extensive studies dealing with the preparation of piezoelectric, electro-optic, dielectric materials with wide use, and hybrids for solid oxide fuel cells (SOFCs) [3, 5-8]. Zirconia is also a material in ceramic industry [9, 10]. 

Ordered mesoporous carbon (CMK-3) has been used as a template to prepare magnetic nanocomposite materials. Wet impregnation of CMK-3 with iron nitrate solution, followed by evaporation of solvent, exposure to acetic add vapour and a sintering step, results in the formation of a hybrid magnetic material. The acetic acid will react with the iron cations dispersed... 

It should be mentioned that the structure of carbon supports could have significant influence on the electro-catalytic properties of the nanocomposite catalysts. Recently, Pt/Ru nanoclusters prepared by the alkaline EG method were impregnated into a synthesized carbon support with highly ordered mesoporous. Although the Pt/ Ru nanoclusters can be well dispersed in the pores of this carbon substrate, the long and narrow channels in this material seem not suitable for the application in... 

Since the 1990s, mesoporous materials have attracted a great deal of attention based on their apphcations in the fields of molecular sorption, ahgnment, confinement, and the formation of nanoclusters. Unlike microporous zeohtes, these materials are usuaUy prepared via template methods, and have ordered hexagonal or cubic charmels with pore diameters ranging from 2 to 10 nm. The internal surface of the mesoporous materials can be modified by covalently anchoring a number of functional groups to their channel walls. Thus, mesoporous materials are also attractive in view not only of controlled polymerization but also the formation of polymer nanocomposites [10]. 

The synthesis of functional polymers inside mesoporous materials has been investigated for the preparation of organic-inorganic nanocomposites, and a... 

Although it is applicable only to certain systems, one of the major interests of this synthetic approach is the possibility to prepare nanocomposites with higher polymer/clay ratios than those prepared by other methods (e.g., in situ polymerization). This is the case for PANl-clay nanocomposites, which are essentially semi-delaminated materials that form well-dispersed systems in water without the loss of the polymer to solution (162). Also, nanocomposites obtained by this route have been used for the preparation of porous materials in which the polymer is removed by calcination (e.g., PVP at 500°C, air). The loss of the polymer produces the rearrangement of clay layers, giving porous solids with mesopores that are in the range 4-10 nm, depending on the molecular weight of the polymer (163,164). 

The EL properties of PVK multilayered EL devices doped with ZnS Mn and based on nanocrystalline particles were also investigated and compared with bulk thin film materials [271], The PVK double layer was fabricated by successive spincoating of PVK and PVK NCs, and the film thickness of each layer was about 100 nm. It was found that multilayer EL devices that exhibited luminance up to thousands of cdm [272] in the case of the application of nanocrystalline parhcles only reached a luminance of the order of 0.1cdm , probably due to an aggregation of nanoparticles. In turn, the properties of ZnSiPVK nanocomposites confined in the MCM-41 silicate were studied [273], To prepare PVK ZnS nanocomposites confined in the silicate, MCM-41 was modified with ethylenediamine followed by introduction of ZnS into their mesopores. Finally, N-vinylcarbazole was mixed with the obtained ZnS/MCM-41 and polymerized at 85°C for 6.5 h. In the PL spectra, an emission peak at 468 nm was observed. Further analysis indicated that the emission could be attributed to the exciplex of excited-state PVK molecules and ground-state ZnS clusters [272],... 

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