Grafting methods, covalent

Covalent binding of ligands to supports is by far the most frequently used strategy for the heterogenization of metal complexes and, in general, the successful catalytic systems are sooner or later immobilized by this method. Covalent binding can be effected either by copolymerization or by grafting. 

To create particles with a hydrophobic core and a hydrophilic shell, preformed hydrophobic polymer particles can be used as substrate for the covalent grafting of hydrophilic polymer chains. Aqueous emulsion polymerization is thus the method of choice for synthesis of core particles with submicrometric diameter (due to the scope of this review article, discussion will be restricted to aqueous emulsion polymerization, although some examples of particle substrates created via suspension polymerization exist however, with much larger diameters). The grafting methods are very close to those used for the surface modification of inorganic materials, such as for instance silicon wafers or colloidal silica particles [46,48-52], Various strategies can be employed such as ... 

In order to construct an ordered monolayer on a carbon surface, a premodified smooth and functionalized film is needed. Electrochemical reduction of diazonium salts or oxidation of amine-containing compounds and arylacetate produces free radicals, resulting in covalent derivatization of the carbon surface in nonaqueous solutions (Figure 3). The premodification by free radical grafting methods is quite mild, simple, and rapid experimentally. The monolayers prepared as a precursor film for subsequent assembly are stable to harsh environments and can endure elevated temperatures, and especially are organized in order, compact, and charge-rich. 

Recently, thermoresponsive star polymers have been reported to be applied to TRCS preparation by using a UV-irradiated polymer grafting method (Park et al., 2010). The star polymer consists of thermoresponsive units, 2-(2-methoxyethoxy) ethyl methacrylate and oligo(ethylene oxide)methacrylate segments, and benzophe-none photoreactive unit, at the internal and peripheral location of the star polymer, respectively. After the star polymers were physically deposited on TCPS surface, the star polymers are mutually cross-linked and covalently grafted on TCPS surfaces by UV irradiation. When the star polymer deposited on TRCS is 31 mn in thickness, cell attachment and detachment is satisfactory. However, TRCS having a thicker polymer layer with a thickness of 39-53 nm shows a poor cell attachment character. 

In nanopattern fabrication, for the preparation of smart materials, surface grafting methods have been employed to attach covalently polymer films to various... 

The modification of polysaccharides is needed to improve the properties of these polysaccharides. Grafting is one of the best methods for the modification of polysaccharides. Graft copolymerization is a process in which side chain grafts are covalently attached... 

The chiral vanadyl salen complex was anchored on mesoporous materials by a covalent grafting method. These heterogenized complex catalysts were evaluated as asymmetric catalysts for the asymmetric oxidation of sulfides to sulfoxides [92]. 

A more sophisticated method was developed by Ren et al. [123] for the immobilization of penicillin G acylase by covalent grafting in the interlayer galleries of a LDH by a three-step procedure using a glutamate pillared LDH as the starting material. 

An alternative approach for covalent polymer attachment is called the grafting from method. This method is based on binding the monomer precursor to the nanotube and generating chain growth directly from the tube. By these means, several types of polymers could be grafted, such as polystyrene-sulfonate [46], polyvinylpyri-dine [47], polystyrene [48] and many others. 

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