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Diazonium salts induced anchoring process: mechanism, application(s)

Abstract : In this work, three surface functionalization processes have been studied: the spontaneous grafting from diazonium salts, the chemically induced grafting from diazonium salts and the chemically induced grafting from diazonium salts in presence of vinylic monomers (which is Graftfast). These processes work at room temperature, atmospheric pressure, in aqueous medium and without any external energy source ("green" chemistry). They lead to the formation of organic films (in particular polymer films in the case of the Graftfast process), stable, strongly grafted and with a controlled thickness (chemically activated processes). Contrary to diazonium salt electrografting methods, the reaction can occur on any type of substrate from insulators to conductors including nanomaterials. The so modified surface can show new properties (for instance water-repellency or protection against corrosion) which is of a major interest in some industrial fields. The main objective of this work was to understand the grafting mechanism of those processes, especially of the Graftfast process, by studying the chemical composition of the films, their structure as well as the composition of the reactive solution. As for classical radical chain polymerization, the mechanism can be split in three steps: initiation, propagation, termination. The polymerization is initiated by aryl radicals in solution coming from the chemical reduction of the diazonium salts (outer sphere or inner sphere mechanism according to the reducing agent used). In parallel, aryl radicals can graft to the surface of the substrate and form an essential polyphenylene primer layer. The propagation stops when the growing polymer chains react on the aromatic rings already grafted on the substrate (termination step). It results an aryl groups/polymers mixed structure of the films. The Graftfast process has been notably tested with a view to improve the dispersion of nano objects in water in the framework of a preliminary study on sunscreens containing TiO2 nanoparticles.
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https://pastel.archives-ouvertes.fr/pastel-00629041
Contributor : Alice Mesnage <>
Submitted on : Tuesday, October 4, 2011 - 6:08:46 PM
Last modification on : Wednesday, November 29, 2017 - 3:02:26 PM
Long-term archiving on: : Thursday, January 5, 2012 - 2:31:38 AM

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  • HAL Id : pastel-00629041, version 1

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Alice Mesnage. Diazonium salts induced anchoring process: mechanism, application(s). Material chemistry. Ecole Polytechnique X, 2011. English. ⟨pastel-00629041⟩

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