Method for grafting and growing a conductive organic film on a surface
The present invention relates to a process for grafting and growing a conductive organic film on(to) an electrically conductive or semiconductive surface in which the grafting and growing of the film are performed simultaneously by electro-reduction of a diazonium salt that is a precursor of the said film on(to) the said surface cathodically polarized at a potential greater than or equal, in absolute value, to the electro-reduction potential of the diazonium salt relative to a reference electrode. The invention finds an application especially in the protection of surfaces, the manufacture of localized conductive coatings, of chemical sensors in the fields of chemistry and molecular biology, the manufacture of biomedical equipment, etc.
1. A process for grafting and growing a conductive organic film onto an electrically conductive or semiconductive surface by electro-reduction of at least one diazonium salt that is a precursor of the organic film, the process comprising grafting and growing the film by application of at least one protocol consisting of the electro-reduction of the at least one diazonium salt onto the surface, the surface being electrically polarized by applying a variable potential ranging from +0.3 V to −2.9 V relative to an Ag + /Ag reference electrode, wherein the organic film is a covering film.
2. The process according to claim 1 , wherein, in the at least one protocol consisting of the electro-reduction, the potential of the surface is applied so as to form a triangular potential pulse.
3. The process according to claim 1 , wherein, in the at least one protocol consisting of the electro-reduction, the potential of the surface is applied so as to form a square potential pulse.
4. The process according to claim 1 , wherein the diazonium salt is a diazonium salt or a mixture of diazonium salts of generic formula R′—N 2 + , X − , in which R′ contains one or more aromatic ring(s) and/or one or more unsaturated group(s) capable of delivering conductive structures, and X − is a counterion.
5. The process according to claim 1 , wherein the diazonium salt is a diazonium salt or a mixture of diazonium salts of generic formula R′—N 2 + , X − , wherein X − is a counterion and R′ comprises an organic or mineral group selected from the group consisting of nitro, fluoro, bromo, chloro, iodo, thiocyanato, sulphate, sulphonate, sulphonium salts, phosphate, phosphonate, phosphonium salts, diazonium salts, amine, ammonium, alcohol, aldehyde, ketone, carboxylic acid, ester, amide, nitrile, anhydride, acid halide, alkyl, alkenyl, alkynyl, aryl, naphthyl, anthryl, pyrryl and polyaromatic groups of higher degree, and wherein the alkyl, alkenyl, alkynyl, aryl, naphthyl, anthryl, pyrryl and polyaromatic groups of higher degree include a group selected from the group consisting of: nitro, fluoro, bromo, chloro, iodo, thiocyanato, sulphate, sulphonate, sulphonium salts, phosphate, phosphonate, phosphonium salts, diazonium salts, amine, ammonium, alcohol, aldehyde, ketone, carboxylic acid, ester, amide, nitrile, anhydride, and acid halide.
6. The process according to claim 1 , wherein the diazonium salt is selected from a tetrafluoroborate, halide, sulphate, phosphate, carboxylate, perchlorate, or hexafluorophosphate salt or a mixture thereof.
7. The process according to claim 1 , wherein the electro-reduction is performed in a medium in which the diazonium salt is at a concentration of between 10 −4 and 1 mol/l.
8. The process according to claim 1 , wherein the diazonium salt comprises one or more aromatic heterocycle(s) and the electro-reduction is performed in a synthetic medium including metal salts.
9. The process according to claim 1 , wherein the electro-reduction of the diazonium salt is performed in a medium comprising a support electrolyte.
10. The process according to claim 1 , wherein the surface is selected from the group consisting of a surface of a noble metal, a surface containing reducible oxide, a graphite surface, a conductive or semiconductive organic surface, a surface of an alloy, a surface of one or more conventional conductive polymer(s), a surface of an intrinsic or doped semiconductor, and combinations thereof.
11. The process according to claim 10 , wherein the surface is a surface of one or more conventional conductive polymer(s) based on pyrrole, aniline, thiophene, ethylenedioxythiophene, acetylene, or polyaromatics.
12. The process according to claim 1 , further comprising a second step of grafting and growing the film by electro-reduction of a second diazonium salt that is different from said at least one diazonium salt.
13. The process according to claim 1 , further comprising a step of depositing an insulating film on the conductive organic film.
14. The process according to claim 1 , further comprising a step of depositing a film of a vinyl polymer by electropolymerization of the corresponding vinyl monomer on the conductive organic film.
15. The process according to claim 1 , wherein the film is included in a multilayer film.
16. The process according to claim 1 , wherein the film is included in a chemical sensor.
17. The process according to claim 1 , wherein the film is included in an encapsulating coating for electronic components.
18. The process according to claim 1 , wherein the film is included in a hydrophilic coating.
19. The process according to claim 1 , wherein the film is included in a biocompatible coating.