Hybrid materials, preparation covalent bonding

This method, based on the reactions of mineral polycondensation, constitutes a very important extension of the classical preparation of oxides using hydrolytic polycondensation [84, 86, 88], One of the most interesting perspectives is its total compatibility with organic chemistry. The firm stability of the Si-C bond also allows this methodology to be extended to the elaboration of hybrid materials where organic and inorganic parts are combined and covalently bonded at the molecular level (Fig. 8). 

Considerable attention has also been paid in recent years to hybrid polymer-silica nanocomposites prepared mostly via a sol-gel process [219,243-254] where 10-100 nm size 3D silica domains (clusters) were covalently bound to the polymer. Polymers deprived of groups reactive in the sol-gel process but prone to hydrogen bonding with silanols of silica nanoparticles have also been successfully incorporated into nanophase-separated hybrid materials [246,248-252]. Some polymer-silica nanocomposites, in particular silica core-polymer shell nanoparticles [255-258], were prepared using 3D fumed silica nanoparticles. 

Covalently functionalized hybrid carbon materials can be prepared by click chemistry. This strategy is been explored by Campidelli et al. to anchor porphyrins and phthalocyanines on CNTs and graphene derivatives [191-193]. Nanomateiials based on covalently bonded GO-P was prepared by condensation reaction of GO and 5,15-pentafluorophenyl-10,20-(4-aminophenyl)porphyrin (P). RGO-P was obtained by electrochemical reduction of GO-P in pH 5 PBS solution and used in dopamine and serotonin biosensors, whose detection limits were found to be 3.5 X 10 and 4.9 x 10 pM, respectively, with negligible interference of ascorbic acid [194]. 

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