Surface chemical groups

Carbon black has been reported to possess different kinds of surface chemical groups. These are aromatics, phenol, carboxylic, etc. The different sites can be estimated by comparing the adsorption characteristics of different adsorbents (such as hexane and toluene). 

Fig. 4. Schematic illustration of the potential surface chemical groups which have been found on the surface of carbon fibers...

The surface chemical groups present on the adherend surfaces consist of species chemically bonded to the surface. A real surface exposed to the environment contains not only the surface chemical groups but also physisorbed water, carbon monoxide and carbon dioxide molecules. The amount adsorbed depends on the surface free energy of the adherend and can range in thickness from portions of a monolayer to multilayers of material. 

The results are plotted in Fig. 14. The upper two lines refer to the A fiber and the lower two lines to the HM fiber. For both fibers, the addition and removal of surface chemical groups did not produce reversible interfacial behavior. The untreated fiber surfaces produced results that could not be duplicated when the surface groups were removed. Microtoming of single fiber specimens pinpointed changes in the locus of interfacial fracture that were relatable to the interphase conditions caused by the surface treatment. 

Fig. 14. The interfacial shear strength versus surface oxygen concentration for the A and HM carbon fibers. The large increase from the untreated (U) case to the surface treated case (S) for both fibers is due to removal of the native defect surface layer plus the addition of surface chemical groups. Removal of the surface groups with various treatments indicates that the surface chemical effect was a minor part of the overall increase. From Drzal et al.751...

It appears, beyond all doubt, that filler-elastomer interactions result in the formation of chemical bonds between the polymer and the solid surface, which are due to a reaction of the macromolecule either with the surface chemical groups or with the surface hydrogen atoms. Is, however, the formation of covalent filler elastomer bonds a prerequisite for reinforcement to occur ... 

When solid sm faces are in contact with a liquid, they may become charged either because of (i) the dissociation of surface chemical groups into the liquid, or (ii) the selective adsorption of ions from the liquid onto the surface [42]. In both cases, a surface electric field is developed due to the charged surfaces, and the electric field extends over a Debye screening length into the bulk liquid. This is due to the presence of charged ions in the solution that redistribute themselves due to the electric field and form a double layer, which screens the electric field, emerging from the surfaces. 

Different cells may prefer different surface chemical group, electrostatic charge, or hydro-phobicity. For active patterning, the limitation of using DEP is the necessity to use buffer that has low dielectric constant. However, cell-culturing medium is aqueous and has high dielectric constant. Therefore, buffer exchange... 

Pereira MFR, Orfao JJM, Figueiredo JL. Oxidative dehydrogenation of ethylbenzene on activated carbon catalysts. I. Influence of surface chemical groups. Appl Catal A 1999 184 153-160. 

Pereira MFR, Soares SF, Orfio JJM, Figueiredo JL. Adsorption of dyes on activated carbons influence of surface chemical groups. Carbon 2003 41(4) 811-821. 

Surface Modification of PS Particles. In addition to uniformity in size, surface chemistry of the polymeric particles is another main consideration for biomedical applications. Monosize polymeric particles having different surface chemical groups were also synthesized from various other monomers (29-52). 

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