Electrochemical reduction of a wide variety of aromatic diazonium salts on carbon electrodes (glassy carbon, highly oriented pyrolytic graphite) leads to the covalent attachment of the corresponding aromatic radicals. The films thus deposited on glassy carbon surfaces require mechanical abrasion to be removed. Cyclic voltammetry, X-ray photoelectron spectroscopy, polarization modulation IR reflection absorption spectroscopy, Auger spectroscopy, and Rutherford backscattering spectroscopy allow the characterization of the overlayer and an estimate of the surface coverage. The latter can be controlled through diazonium concentration and electrolysis duration. The mechanism of derivatization is discussed on the basis of the kinetic data obtained from cyclic voltammetry and preparative electrolysis. This versatile method of surface modification may find applications in the field of carbon−epoxy composites as attested by the successful binding of grafted p-aminophenyl groups with epichlorhydrin.

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The chemical grafting of iron surfaces at open-circuit potential by reduction of different aryldiazonium salts in aqueous acidic solution occurs spontaneously without the need of electrochemical assistance. X-ray photoelectron spectroscopy (XPS) and IR allowed to evidence the grafting of organic moieties without any adsorption of diazonium salts. The aryl groups are strongly bonded to the metal since they can withstand sonication in acetone. XPS measurements also show that spontaneous grafting in water is at least as efficient as electrochemical grafting and also indicate the presence of a multiphenyl layer coverage of the iron surface. The surface film of carboxyphenyl groups on iron was chemically derivatized further by octyltriethoxysilane. The anticorrosive effects of the different films were evaluated in 0.01 M H 2 SO 4 aqueous solution, by polarization and impedance measurements. Grafting of the diazonium salt results in an inhibition efficiency up to 73%, which can be slightly increased up to 85% by derivatization of the film by octyltriethoxysilane. The inhibition efficiency can be significantly improved up to 97% when the grafted metal is left in the corrosion medium in the presence of the diazonium salt.

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The surface composition of electrically conductive polypyrrole-coated polystyrene latex particles has been examined by X-ray photoelectron spectroscopy (XPS). We have systematically characterized the surface of polystyrene (PS), poly(N-vinylpyrrolidone) (PNVP), chloride-doped polypyrrole (PPyCl) powder, and PNVP-stabilized PS latex in order to determine the relative contributions of PS (core), PNVP (stabilizer), and PPyCl (shell) to the surface composition of the PPyCl-coated PS latex. XPS was found to be very effective in detecting PNVP at the surface of uncoated PS latex using N1s signal as an elemental marker and showed that the former polymer contributes to ca. 50% of the PS latex surface. In contrast, the surface composition of PPyCl-coated PS latex was found to be very PPyCl-rich, since the PPyCl bulk powder and the PPyCl-coated PS latex have very comparable XPS spectra. However, some additional iron chloride species (FeCl2 and/or FeCl3 -) were also detected as impurities at the surface of the coated latex.

Indium tin oxide (ITO) substrates have been modified by alkanethiol and fatty acid self-assembled monolayers (SAMs). The SAMs were grown by dipping the cleaned surface into either a pure alkanethiol or a fatty acid dissolved in various solvents. They were characterized through contact angle, X-ray photoelectron (XPS) and infrared absorption-reflection spectroscopy (IRRAS). Their density and structural organization was found to greatly depend on the cleaning treatment of the ITO surface, the length of the alkyl chain, and, in the case of fatty acids, the concentration of the solution. XPS measurements brought evidence for the fact that, in the case of alkanethiols, the grafting mechanism was through the formation of ionic or covalent bonds involving thiolates. The most prominent result of this comparative study is that thiol-based SAMs are more strongly attached to the ITO substrate and better organized than fatty acids, which we attribute to the fact that the reaction of the ITO surface with fatty acids is more reversible than that with thiols.