Formation of organic electro-grafted films on the surface of electrically conductive or semi-conductive surfaces
The invention relates to a method for grafting an organic film onto an eclectically conductive or semiconductive surface by electro-reduction of a solution, wherein the solution comprises one diazonium salt and one monomer bearing at least one chain polymerizable functional group. During the electrolyzing process, at least one protocol consisting of an electrical polarization of the surface by applying a variable potential over at least a range of values which are more cathodic that the reduction or peak potential of all diazonium salts in said solution is applied. The invention also relates to an electrically conducting or semiconducting surface obtained by implementing this method. The invention further relates to electrolytic compositions.
1 . An electrically conducting or semiconducting surface, comprising: an organic film layer, grafted on said surface, or portion of said surface, and an outer layer adhered to the organic film layer by interdigitation, wherein the organic film layer comprises the chemical structure of at least one monomer or macro-object comprising a group that can be involved in propagation chain reactions and which is precursor of said organic film layer, and a moiety of an aryldiazonium salt or its electro-reduction by-products,
wherein the organic film layer has a thickness from 10 nm to 10 μm; and
wherein the organic film layer is not homogeneous in a direction perpendicular to the surface, the organic film layer being richer in diazonium and its electro-reduction by-products close to the surface, while farther from the surface, the organic film layer is richer in polymer.
2 . The surface of claim 1 , wherein the organic film layer is a polymeric or nonpolymeric macrostructure functionalized with at least one group that can be involved in propagation chain reactions.
3 . The surface of claim 1 , wherein the organic film layer is a vinylic polymer or copolymer.
4 . The surface of claim 1 , wherein the monomer is an activated vinylic group or a cyclic molecule cleavable by nucleophilic attack.
5 . The surface of claim 1 , wherein said surface is a surface of stainless steel, cobalt or its alloys, titanium or its alloys, iron, copper, nickel, niobium, aluminum, silver, silicon (doped or not), silicon carbide, titanium nitride, tungsten, nitride of tungsten, tantalum, nitride of tantalum or a noble metal surface chosen from platino-iridium or iridium, platinum, and gold surfaces.
6 . The surface of claim 4 wherein the cyclic molecule has formula (II):
in which:
R1 and R2, identical or different, represent a hydrogen atom; a C1-C4 alkyl group; a nitrile group; a function selected from the group consisting of hydroxyl, amine —NHx with x=1 or 2, ammonium, thiol, carboxylic acids and their salts, ester, amide —C(═O)NHy in which y=1 or 2, imide, imido-ester, acid halide C(═O)X in which X represents an halogen atom chosen among fluorine, chlorine, bromine and iodine, acid anhydride —C(═O)OC(═O), amino-acids, phosphonic acids and their salts, phosphoric acids and their salts, phosphonyl choline and its derivatives, sulfonic acids and their salts, sulfuric acids and their salts, nitrile, succinimide, phthalimide, isocyanate, epoxy, siloxane —Si(OH)z in which z is a whole number ranging between 1 and 3 inclusively, benzoquinone, carbonyl-diimidazole, para-toluene sulphonyl, para-nitrophenyl chloroformiate, ethylene and vinyl, aromatic; a functional group being able to complex cations; molecular structures substituted and/or functionalized starting from these functional groups; thermally or photochemically cleavable groups, electroactive groups, aniline, thiophene, methylthiophene, bis thiophene, pyrrole, ethylene dioxothiophene (EDOT) and analogues, as well as electro-cleavable, as well as mixtures of monomers containing the aforementioned groups;
the straight line of formula (II) represents a C3-C10 alkyl radical;
n, m and p, identical or different, are whole numbers ranging between 0 and 20 inclusively, under the proviso that n, m, and p are not at the same time 0.
7 . The surface of claim 6 , wherein the cyclic molecule is chosen from epoxies, lactones, lactic acids, glycolic acids, oxiranes, polyaspartate, and any mixtures thereof.
8 . The surface of claim 4 , wherein the activated vinyl monomer has the formula (I):
in which:
A, B, identical or different, represent a hydrogen atom; a C1-C4 alkyl group; a nitrile group; a function selected from the group consisting of hydroxyl, amine —NHx with x=1 or 2, ammonium, thiol, carboxylic acids and their salts, ester, amide —C(═O)NHy in which y=1 or 2, imide, imido-ester, acid halide C(═O)X in which X represents an halogen atom chosen among fluorine, chlorine, bromine and iodine, an acid anhydride —C(═O)OC(═O), amino-acids, phosphonic acids and their salts, phosphoric acids and their salts, phosphonyl choline and its derivatives, sulfonic acids and their salts, sulfuric acids and their salts, nitrile, succinimide, phthalimide, isocyanate, epoxy, siloxane —Si(OH)z in which z is a whole number ranging between 1 and 3 inclusively, benzoquinone, carbonyl-diimidazole, para-toluene sulphonyl, para-nitrophenyl chloroformiate, ethylene and vinyl, aromatic; a functional group being able to complex cations; molecular structures substituted and/or functionalized starting from these functional groups; thermally or photochemically cleavable groups; electroactive groups, aniline, thiophene, methylthiophene, bis thiophene, pyrrole, ethylene dioxothiophene (EDOT) and analogues, as well as electro-cleavable groups, as well as mixtures of monomers containing the aforementioned groups.
9 . The surface of claim 4 , wherein the activated vinylic monomer is chosen from the group consisting of acrylonitrile, methacrylonitrile, methyl, ethyl, propyl and butyl methacrylate, hydroxyethyle hydroxypropyle glycidyle methacrylate, acrylamides, cyanoacrylates, di-acrylates or di-methacrylates, tri-acrylates or tri-methacrylates, tetra-acrylates or tetra-methacrylates, acrylic and methacrylic acid, styrene and its derivatives, parachlorostyrene, pentafluorostyrene, N-vinyl pyrrolidone, 2-vinyl pyridine, vinyl acryloyle, methacryloyle halides, and di-vinylbenzene (DVB).
10 . The surface of claim 2 , wherein the macrostructure is functionalized with a vinylic group selected from the group consisting of methacrylate, acrylate, vinyl chloride, acrylonitrile, methacrylonitrile, 4-vinylpyridine, 2-vinylpyridine, and N-vinylpyrrolidone.
11 . The surface of claim 1 , wherein the macro-object is an object of nanometric or micrometric size, the surface of which being functionalized with vinyl groups activated with electro-withdrawing groups or cyclic groups.
12 . The surface of claim 1 , wherein the organic film layer has no crosslinking.
13 . The surface of claim 1 , wherein the aryldiazonium salt is nitrophenyl diazonium, the monomer is BUMA, the organic film layer is a polymeric film that is not homogeneous in a direction perpendicular to the surface, wherein close to the surface, the film is richer in nitrophenyl diazonium and its electro-reduction by-products, while farther from the surface, the film is richer in poly-BUMA.
14 . An object comprising a surface of claim 1 .
15 . The object of claim 14 , wherein the object is biocompatible.
16 . The object of claim 14 , wherein the conductive surface is a 316L stainless steel coupon, the organic film layer is a 150 nm poly-BUMA layer, grafted on a 316L stainless steel coupon, and further comprising an outer coating that is a 5 micrometer PLA layer.
17 . The object of claim 14 , wherein the object is a stent.