Carbon black surface chemical structure

Chemical heterogeneity of a surface is an important property affecting adhesion, adsorption, wettability, biocompatibility, printability and lubrication behavior of a surface. It seriously affects gas and liquid adsorption capacity of a substrate and also the extent of a catalysis reaction. As an example, the partial oxidation of carbon black surfaces has an important, influence on their adsorptive behavior. In a chemically heterogeneous catalyst, the composition and the chemical (valence) state of the surface atoms or molecules are very important, and such a catalyst may only have the power to catalyze a specific chemical reaction if the heterogeneity of its surface structure can be controlled and reproduced during the synthesis. Thus in many instances, it is necessary to determine the chemical... 

Oxygenated Functions. Oxygenated functions on carbon black surface were observed in the early 1950s [70] and completely characterized by H. P. Boehm in the 1960s [71]. At this time, interaction between carbon black and natural rubber was considered the consequence of chemical reactions between the carbon black surface s acidic groups and basic moieties present in the natural rubber structure [71a]. 

In the case of the interaction of acetonitrile with the carbon black surface, molecules bound to the surface are characterized by a single signal at 8g 2.5 ppm (Figure 4.1c) whose chemical shift does not depend on temperature and is similar to the chemical shift of liquid acetonitrile. Consequently, acetonitrile molecules interact weakly with basal graphite planes of the surface and do not penetrate into narrow nanopores. The most probable mechanism of interactions in this case is that of dipole-dipole interactions of the CHjCN molecules with polar groups that are predominantly situated on end faces and structural defects of basal planes of graphite in broad mesopores. 

Adsorptiou ou the carbon black surface depends mainly on the geometry of the adsorbate molecules aud their polarizability. Thus, graphitized carbon black is an ideal adsorbent for separation of isomers of similar physical properties but of different geometrical structures, because of its surface homogeneity [18]. Chemical modification of carbon black, on the other hand, enhances specific adsorption affinity by virtue of the presence of different functional groups on its surface [17,19]. 

Many solids have foreign atoms or molecular groupings on their surfaces that are so tightly held that they do not really enter into adsorption-desorption equilibrium and so can be regarded as part of the surface structure. The partial surface oxidation of carbon blacks has been mentioned as having an important influence on their adsorptive behavior (Section X-3A) depending on conditions, the oxidized surface may be acidic or basic (see Ref. 61), and the surface pattern of the carbon rings may be affected [62]. As one other example, the chemical nature of the acidic sites of silica-alumina catalysts has been a subject of much discussion. The main question has been whether the sites represented Brpnsted (proton donor) or Lewis (electron-acceptor) acids. Hall... 

The physicochemical properties of carbon are highly dependent on its surface structure and chemical composition [66—68], The type and content of surface species, particle shape and size, pore-size distribution, BET surface area and pore-opening are of critical importance in the use of carbons as anode material. These properties have a major influence on (9IR, reversible capacity <2R, and the rate capability and safety of the battery. The surface chemical composition depends on the raw materials (carbon precursors), the production process, and the history of the carbon. Surface groups containing H, O, S, N, P, halogens, and other elements have been identified on carbon blacks [66, 67]. There is also ash on the surface of carbon and this typically contains Ca, Si, Fe, Al, and V. Ash and acidic oxides enhance the adsorption of the more polar compounds and electrolytes [66]. 

Comparing the three substrates that were plasma-coated in this study, it has become clear that silica is very easy to encapsulate with a plasma coating, whereas carbon black is difficult to treat because of its inert chemical surface structure. Sulfur is also more difficult to handle, but in this case the incomplete coating is an advantage because the sulfur has to be released from the encapsulation shell in order to be efficient as curing agent. In all cases, the polarity of the substrate is reduced. 

The present review discusses the results of the H NMR spectroscopy for a wide range of carbonaceous materials (heat-treated and nongraphitizable activated carbons, carbon blacks, exfoliated and oxidized graphites, porous and amorphous carbonized silicas). This technique made it possible to determine the spectral characteristics of organic molecules with diverse chemical properties, as well as of water molecules adsorbed on the surface. These characteristics are compared with the structural properties of the materials under consideration. The calculations done for the majority of the subjects of inquiry gave the values of their free surface energies in an aqueous medium as well as the characteristics of bound water layers of various types. 

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