Surface Electroinitiated Emulsion Polymerization: grafted organic coatings from aqueous solutions
Résumé
The Surface Electroinitiated Emulsion Polymerization (SEEP) protocol, described here for the first time, combines the advantages of the electrografting process, which delivers thin organic coatings chemically bonded to conducting surfaces, with polymerization in emulsion, which allows synthesizing hydrophobic polymers in aqueous solutions. From the mechanistic point of view, SEEP combines the 'grafting to' and 'grafting from' methods in one fast electrochemical step at room temperature, taking advantage of the ability of diazonium salts to (i) be easily electrografted on conducting surfaces under moderate cathodic conditions and (ii) act as an initiator for the radical polymerization of vinylic monomers in emulsion . This work is a preliminary description of this process applied to various vinylic monomers like acrylic acid (AA), acrylonitrile (AN) and butyl methacrylate (BUMA). Experiments showed that the process works correctly whatever the surfactant used. In all cases, the surface initiation was obtained via the electrochemical reduction of nitrobenzenediazonium tetrafluoroborate salts. The resulting grafted copolymer (poly(nitrophenylene, vinylics)) was obtained and characterized by infrared (IRRAS) and photoelectron (XPS) spectroscopies.