Covalent surface modification

A number of nanotube surface modification approaches have been reported in the recent years. Non-covalent surface modifications aim to physically wrap polymer chains around the nanotubes or adsorb various surfactant molecules on the surface of nanotubes. Thus,... 

Covalent surface modification with poly(AAP) consist of the following steps ... 

Jana, M., P. Khanra, N. C. Murmu, P. Samanta, J. H. Lee, and T. Kuila. 2014. Covalent surface modification of chemically derived graphene and its application as supercapacitor electrode material. Physical Chemistry Chemical Physics 16 7618—7626. 

This strategy is based on the covalent attachment of functional groups to the C=C double bonds of the polyaromatic network of CNTs. By adjusting the reaction conditions (i.e., catalysts and reactants concentration, temperature and solvent), this strategy has allowed the selective and controlled modification of CNTs and, due to the nature of the bonds, has provided long-term stability to the dispersion. Nevertheless, the two main drawbacks of covalent surface modification are (i) the inevitable loss of their electrical and/or electronic properties [49] and (ii) the low degree of functionalization. 

Much research has been eondueted in the past decade in studying surface modifieation of earbon nanotubes. These efforts basically fall into two categories covalent and non-covalent modifieation. Covalent surface modification of the reinforeing material involves a permanent ehange to the material surfaee such that it is functionalized with reaetive groups whieh ean later form a covalent bond with... 

Many particle types contain functional groups that are built into the polymer backbone and displayed on their surface. The quantity of these groups can vary widely depending on the type and ratios of monomers used in the polymerization process or the degree of secondary surface modifications that have been done. Some common particle functionalities are shown in Figure 14.6. Many of these functionalized particles can be used to couple covalently biomolecules through the appropriate reaction conditions (Ilium and Jones, 1985 Arshady, 1993). For each type of particle, manufacturers may offer several different densities of functional groups for different applications. 

In order to overcome this drawback, there are two main approaches for the surface modification of carbon nanostructures that reoccur in the literature. The first one is covalent functionalization, mainly by chemical bonding of functional groups and the second one is noncovalent functionalization, mainly by physical interactions with other molecules or particles. Both strategies have been used to provide different physical and chemical properties to the carbon nanostructures. Those that will be presented here are only a few examples of the modifications that can be achieved in carbon nanostructure surfaces and composite fabrication. 

Mrksich and co-workers developed a MALDI-based assay scheme making use of a target surface modification by self-assembled monolayers (SAMs) [22]. This combination of SAMs and MALDI is predominantly called SAMDI (selfassembled monolayers for MALDI). For SAMDI, a self-assembled monolayer with reactive end groups is used in order to covalently bind enzyme substrates to a surface. To... 

PDMS in its native form does not possess reactive groups that can be used for the covalent attachment of NAs [51]. However, the PDMS surface can be plasma induced oxidized and then fimctionaUzed with organosilanes carrying the desired head group. For example, a PDMS surface has been modified with 3-mercaptotrimethoxysilane to yield a thiol-terminated surface, to which a 5 -acrylamide modified DNA has been covalently attached [52]. See Fig. 13 for a representation of the PDMS surface-modification process. 

Structures of immobilized rhodium complexes on the sihca support have been proposed on the basis of the data obtained from C, P and Si MAS-NMR. NMR spectra of the rhodium-modified solid materials confirmed that trimethylsiloxide ligand was removed from the rhodium coordination sphere during the immobilization process. Formation of a new covalent bond between the rhodium organo-metallic moiety and the silica support occurs, probably with evolution of trimethylsilanol, which is rapidly converted into disiloxane (Me3Si)20. The presence of this molecule in the solution obtained after the silica surface modification process was confirmed by GCMS analysis. 

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