Nanostructured materials homogenization

Because of the considerable variety of materials that can be classified as porous, the discussion will be limited to several groups porous silicates and aluminosilicates, porous metal oxides and related compounds, porous polyoxometalates, metal-organic frameworks, porous carbons, carbon nanotubes, and several hybrid materials. All these materials can be viewed as relatively homogeneous from the electrochemical point of view. Metal and metal oxide nanoparticles, organic metals, fullerenes, and dendrimers, which can also be regarded as nanostructured materials, also displaying distinctive electrochemical features, will not be treated here for reasons of brevity, although their appearance in hybrid materials as modifiers for microporous materials will be discussed. 

Palladium metal particles with an average diameter of ca. 5 nm were homogeneously dispersed inside carbon nanotubes. Such nanostructured material was an extremely active and selective catalyst for the hydrogenation of the C=C bond of cinnamaldehyde. The high external surfece area of the carbon nanotubes could explain the high reactivity of the catalyst despite its relatively low specific surfece area, i.e. 20 m. g". On the other hand, the high selectivity towards the C=C bond hydrogenation was attributed to the absence of a microporous network and of residual acidic sites in the carbon nanotube catalyst as compared to a commercial activated charcoal. 

Previous investigations have demonstrated that use of HPT provides an ability to produce homogeneous nanostructures with a grain size of about 100 nm and less [7,11,13], These earlier studies have allowed to consider this method as an SPD technique for bulk nanostructured materials processing. 

There is a strong necessity to define formulations components processes conditions for nanostructured materials filled by metallic additives. Another task is optimization of components, nanocomposites and diluents combination and, in what follows, curing processes with determined temperature mode. The result of these arrangements will be materials with layerwise homogeneous metal particles/nanocomposites distribution formulation in ligand shell. 

Mesoscopic materials form the subset of nanostructured materials for which the nanoscopic scale is large compared with the elementary constituents of the material, i. e. atoms, molecules, or the crystal lattice. For the specific property under consideration, these materials can be described in terms of continuous, homogeneous media on scales less than that of the nanostructure. The term mesoscopic is often reserved for electronic transport phenomena in systems structured on scales below the phase-coherence length A0 of the carriers. 

Nanostructured materials or nanocomposites based on polymers have been an area of intense industrial and academic research over the past one-and-a-half decades [7-12]. In principle, nanocomposites are an extreme case of composite materials in which interface interactions between two phases are maximized. In the literature, the term nanocomposite is generally used for polymers with submicrometer dispersions. In polymer-based nanocomposites, nanometersized particles of inorganic or organic materials are homogeneously dispersed as separate particles in a polymer matrix. This is one way of characterizing this type of material. There is, in fact, a wide variety of nanoparticles and a way to differentiate them and to classify them by the number of nanoscale dimensions they possess. Their shape varies and includes (i) one-dimensional needle- or tube-like structures, for example, inorganic nanotubes, carbon nanotubes, sepio-lites, and so on (ii) two-dimensional platelet structures, for... 

For nanostructured materials that improved compatibility, it is expected that this can lead to a serious shift in the crystaUization temperature toward lower temperatures. Thereby leading ultimately to a more pronounced fractionated crystallization or even resulting in a homogeneous aystallization. Just as discussed for crystallizable matrix, the crystallizable dispersed phase may crystallize in the presence of either melt or glassy amorphous matrix. 

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