International audienceCovalent surface modification of conductive, semiconductive, and insulating substrates with thin organic polymers films induced by redox activation of aryl diazonium salts in the presence of vinyl monomers has been investigated in acidic aqueous media. This new process, called diazonium-induced anchoring process (DIAP), is an efficient technique to impart covalent adhesion of polyvinyl coatings onto raw inorganic or organic surfaces without any conductivity requirement. Typically, aryl diazonium salts are reduced with iron powder to give surface-active aryl radicals leading (i) to the formation of a grafted polyphenylene-like film on the substrate surface and (ii) to the initiation of the radical polymerization of the vinylic monomer in solution. The resulting radical-terminated macromolecular chains formed in solution are then able to react with the polyphenylene primer layer to form a very homogeneous thin organic film on the surface. The final organic thin coating is strongly grafted on materials surfaces, as evidenced by its persistence after a long ultrasonic treatment in a good solvent of the polymer. We speculate this process is supported by the large concentration of aryl and hydrogen radicals formed when iron powder is added in the acidic aqueous solution. The thickness of the polymer film can be controlled as a function of time, typically a few minutes, and was measured between 10 and several hundred nanometers. Infrared reflection–absorption spectroscopy (IRRAS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and contact angle measurements were used to characterize the surface modification of metals, glass, carbon nanotubes, or polytetrafluoroethylene (PTFE). This very simple and efficient grafting method provides a powerful tool for the covalent coating of organic or inorganic surfaces possessing complex geometrical shapes

As recently reported, the SEEP process (surface electroinitiated emulsion polymerization) is a new grafting method that provides covalently grafted polymer films on conducting or semiconducting surfaces by radical polymerization in aqueous dispersed media. It relies on cathodic electroinitiation, which creates radical species able to start a radical polymerization. Contrary to the formerly described cathodic electrografting of vinylic polymers (CE), which also delivers submicrometerthick and stable polymer films on conducting substrates but requires strictly anhydrous conditions and organic aprotic solvent, SEEP brings a major improvement in switching from a purely anionic mechanism to a radical one by adding an aryldiazonium salt in the reaction mixture, while retaining the same polymer films characteristics. Moreover, SEEP is not restricted to water-soluble monomers but can be performed even with hydrophobic ones, such as n-butyl methacrylate (BMA). In such cases, a surfactant is necessary to stabilize the monomer in water emulsion. From this one-pot electrografting process performed in water at room temperature, in a few minutes, without restrictions on vinylic monomer water solubility, results a polymer coating strongly grafted to the substrate. This article aims at completing our first one and focuses on mechanistic aspects of SEEP to eventually establish a possible "grafting onto" mechanism. To achieve that goal, we have analyzed grafted polymer films obtained by SEEP on gold substrate from BMA in water as a miniemulsion by IR-ATR, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), and atomic force microscopy (AFM).