Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
  • C01B32/15—Nano-sized carbon materials
  • C01B32/158—Carbon nanotubes
  • C01B32/168—After-treatment
  • C01B32/172—Sorting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y40/00—Manufacture or treatment of nanostructures
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2202/00—Structure or properties of carbon nanotubes
  • C01B2202/02—Single-walled nanotubes
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2202/00—Structure or properties of carbon nanotubes
  • C01B2202/20—Nanotubes characterized by their properties
  • C01B2202/22—Electronic properties
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2202/00—Structure or properties of carbon nanotubes
  • C01B2202/20—Nanotubes characterized by their properties
  • C01B2202/34—Length
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2202/00—Structure or properties of carbon nanotubes
  • C01B2202/20—Nanotubes characterized by their properties
  • C01B2202/36—Diameter

Definitions

• the present invention belongs to the field of nanotechnologies and, in particular, to the field of nano-objects such as carbon nanotubes and, in particular, carbon nanotubes SWNT.
• the present invention aims to provide a method for separating, in a selective and specific manner, the metallic SWNT carbon nanotubes and the semiconducting SWNT carbon nanotubes.
• the process according to the invention is based on the reaction of SWNT nanotubes with a diazonium salt derivative.
• the present invention also provides a kit for implementing such a method.
• Nanomaterials and especially carbon nanotubes are currently attracting particular interest because of their original and exacerbated properties compared to conventional materials. Carbon nanotubes are a promising new material for organic electronics.
• a carbon nanotube is defined as a concentric winding of one or more layers of graphene (paving carbon hexagons).
• SWNT for "Single Wall NanoTube”
• MWNT for "Multi Wall NanoTube”
• nanotubes Due to their unique structure and their dimensions characterized by a length / diameter ratio, nanotubes have exceptional mechanical, electrical and thermal properties.
• the SWNTs can be either metallic, ie conductors with an electrical resistance as low as 1 to 2 k ⁇ for a diameter of 1 to 2 nm, or half conductors, with a growing gap as the diameter decreases (typically 0.5 to 1.2 eV).
• a large scientific literature has demonstrated the interest of SWNTs, thanks to their high conductivity and their metallic or semiconductor character, in electronic applications in field effect transistors, in high frequency devices, in variable resistors, in as pixels, as chemical detector in liquid or gaseous phase, etc.
• SWNTs are dissolved in water using one or more surfactants.
• the surfactants surround the SWNTs, the surfactant-SWNT combination being selective as a function of their metallic or semiconductor type.
• the surfactant-SWNT complexes have different densities and can be separated by ultracentrifugation on a density gradient (Arnold et al., 2006 [2]). As the ultracentrifugations are carried out on limited volumes, the purified quantities are necessarily limited but the samples can be obtained with a good degree of purity.
• the difference in the association with surfactants can be used to obtain a difference in the overall load of SWNTs.
• International application WO 2003/084869 [3] describes a method of separation based on a different protonation of SWNTs surrounded by surfactants, in solution, according to their chirality (n, m). At a given pH, a voltage is applied to attract charged nanotubes to the electrode and a fraction is collected. The process is repeated at different pHs allowing the collection of enriched fractions with different chirality (n, m).
• the DNA can be used as a polymeric surfactant for the solubilization of SWNT and oligomers of different sequence and length were used to separate SWNTs.
• SWNT-DNA adducts can then be separated by ion exchange chromatography, the first fractions being enriched in small diameter metal SWNTs and the last large diameter SWNT semiconductor fractions.
• US patent application 2006/0223068 [4] relates to SWNT-DNA hybrids and, more particularly, to the solubilization of SWNTs by enveloping with DNA. The DNA envelops the SWNTs to form a soluble, rather unstable hybrid.
• International application WO 2004/048256 [5] proposes a method for separating m-SWNTs and sc-SWNTs based on their solubilization using short single-stranded DNA molecules.
• SWNTs can be separated using standard chromatography, electrophoresis, ion exchange chromatography, or two-phase systems.
• the complexation can be used in a simpler way and this by solubilizing part of the SWNT in a bad solvent.
• SWNTs are insoluble in water and most organic solvents.
• Ligands selected for their selectivity for the chirality or diameter of SWNTs such as porphyrin which is a specific SW-SWNT ligand can be used to wrap and solubilize them.
• International application WO 2006/013788 [6] describes a method for separating m- and sc-SWNTs based on their different solubility in amines.
• the m-SWNTs and the sc-SWNTs can also be separated according to their electromagnetic properties.
• the difference in the polarizability of m-SWNTs and sc-SWNTs has already been exploited to separate them. Indeed, the dielectrophoretic attractive force applied by a high frequency AC electric field on the m-SWNTs is greater than that of the sc-SWNTs.
• International application WO 2005/030640 [7] describes a separation method based on the difference of the polarizable character and based on optical trapping for the separation. SWNTs are trapped by a focused laser beam and can be moved in a microfluidic system from one channel to another by moving the laser beam.
• SWNTs of different chirality are trapped at different wavelengths of the laser, making it possible to move the SWNTs according to their chirality.
• a first selective and simple treatment is the oxidation of small diameter m-SWNT under aggressive conditions.
• International application WO 2005/041227 [8] proposes a method based on the application of a voltage on SWNTs deposited on a substrate to protect a type of SWNT, the unprotected type being either burned or chemically destroyed by for example, by treatment with a strong acid.
• the selective oxidation of SWNTs has also been described with electrophilic compounds such as nitronium ions N ⁇ 2 + whose attack functionalizes large diameter sc-SWNTs and destroys small diameter m-SWNTs.
• the patent application US 2005/0255031 [9] is based on a selective oxidation with nitronium ions. Less aggressive oxidation conditions result in preferential functionalization of the m-SWNTs.
• SWNTs small diameter m-SWNTs.
• the reduction of SWNTs can be followed by alkylation for separation.
• the inorganic functionalization of SWNTs generally involving the reduction of a salt on the surface of SWNTs has also been used to separate SWNTs.
• the patent application US 2007/0258880 [10] describes a method for separating m-SWNTs and sc-SWNTs based on the photochemical reduction of a metal salt on the surface of SWNTs in solution. The photochemical reaction is selectively induced on one type of SWNT by irradiating the solution at their absorption wavelength. The metal-coated SWNTs can be separated from the solution under the action of a magnetic field.
• WO 2004/043857 [13] proposes a method for separating m-SWNTs and sc-SWNTs using a terminal bond to a polymer.
• the polymer promotes solubility in solution and the bond between the polymers and the SWNTs can be selectively broken by repeated heat treatment at increasing temperatures.
• SWNTs without bound polymer are separated by filtration.
• SWNT CoMoCat or HiPco small diameter SWNTs
• small diameter SWNTs show greater chemical reactivity in general, due to the greater curvature of the rolled graphene sheet which induces tension on the C-C bonds.
• These samples also contain a smaller number of different chirality, purifying a single chirality.
• electronic devices are difficult to obtain from small diameter SWNTs.
• sc-SWNT devices can only be manufactured on a large scale if sc-SWNT-based fractions are of sufficiently high purity to prevent short-circuits of m-SWNTs.
• the object of the present invention is to provide a functional process which meets, inter alia, the needs indicated above and which solves the technical problems of the processes of the prior art.
• the object of the present invention therefore relates to a method for separating, selectively and specifically, SWNT semiconductors and metal SWNT and whatever their size.
• FIG. 1 shows the evolution of the SWNT absorption spectra of diameters of 1.2 to 1.4 nm reacting with bromobenzenediazonium tetrafluoroborate (BrBDT) of formula N 2 + -CeH 4 -Br, BF 4 ".
• BrBDT bromobenzenediazonium tetrafluoroborate
• the metal absorption peaks and semiconductor can be viewed respectively at 600-700 nm and 900-1000 nm, successive spectra overlap.
• the peak of m-SWNT decreases more rapidly than peak of sc-SWNT, but functionalization only of m-SWNT is not possible.
• the m-SWNT vs sc-SWNT selectivity defined here as the ratio of the reaction rate of m-SWNT vs that of sc-SWNT, ranges from 2 to 4 depending on the substituent of aryl diazonium (selectivity is 3 in Figure 1) but does not depend on the concentration of diazonium nor the concentration of SWNT.
• the Applicant has shown that the use not of a diazonium salt but of a derivative of a diazonium salt makes it possible to reduce the selectivity by a factor of between 2 and 4 to a factor understood between 6.4 and 15 (data in Table 1 below).
• the fact that the improvement of the selectivity and therefore the specificity is mainly due to the use of a diazonium salt derivative has been confirmed experimentally.
• the present invention thus relates to a method for separating single-layered metal graphene carbon nanotubes (m-SWNT) and semiconductor graphene single-layer nanotubes (sc-SWNT) comprising a step of reacting a derivative of diazonium salt on a mixture of m-SWNT and sc-SWNT.
• said step consists in reacting, by radical chemical grafting, a diazonium salt derivative on a mixture of m-SWNT and sc-SWNT.
• the present invention relates to a method for separating carbon nanotubes from a single metal graphene layer (m-SWNT) and semiconductor graphene single-layer nanotubes (sc-SWNT) comprising a grafting step of a diazonium salt derivative on a mixture of m-SWNT and sc-SWNT of so as to obtain a mixture of grafted m-SWNTs and non-grafted sc-SWNTs, whereby the grafted m-SWNTs and the ungrafted sc-SWNTs separate due to the differential chemical and / or physical properties caused by said grafting .
• the grafting used is a radical chemical grafting.
• separation process is meant, in the context of the present invention, both a physical separation method that a method for distinguishing m-SWNT from sc-SWNT in the same mixture. This separation is based on the differential chemical and / or physical properties between the selectively and specifically grafted m-SWNTs and the ungrafted sc-SWNTs. Examples of such properties will be given below.
• SWNT single layer graphene nanotubes
• Those skilled in the art know different techniques for preparing such carbon nanotubes. Examples include physical processes based on carbon sublimation such as electric arc methods, laser ablation or using a solar oven. These processes are described and explained from line 4, page 2 to line 25, page 3 of the international application WO 03/084869 [3].
• the nanotubes used in the context of the present invention are carbon nanotubes with a single layer of graphene having a length of between 10 nm and 400 ⁇ m, in particular between 20 nm and 200 ⁇ m, in particular between 50 nm and 100 ⁇ m and, in particular, between 100 nm and 80 ⁇ m and a diameter of between 0.2 and 6 nm, especially between 0.6 and 4 nm and, in particular, between 1 and 2 nm.
• derivative of diazonium salt is meant, in the context of the present invention, a product obtained by reaction of a diazonium salt with a compound C selected from the group consisting of an organic acid, a sulfoxide, an alcohol and one of their salts.
• the organic acid, the sulfoxide or the alcohol may be in the form of salts.
• said organic acid is selected from the group consisting of a carboxylic acid, a phosphonic acid, a sulfonic acid.
• carboxylic acid is meant, in the context of the present invention, a compound of formula R1-COOH in which R1 represents a hydrocarbon group of 1 to 20 carbon atoms such as an alkyl group, an alkenyl group, a alkoxy group, an aryl group, an aryloxy group or a carboxylic group.
• phosphonic acid is meant, in the context of the present invention, a compound of formula R2-PO (-OH) 2 in which R2 represents a hydrocarbon group of 1 to 20 carbon atoms such as an alkyl group, an alkenyl group, an alkoxy group, an aryl group or an aryloxy group.
• alcohol is meant in the context of the present invention, a compound of formula (R 7 R 8 R 8 ) C-OH in which R 7 , R 5 and R 8 independently represent an alkyl group or a hydrogen.
• alkyl group is meant, in the context of the present invention, a linear, branched or cyclic alkyl group, optionally substituted, of 1 to 20 carbon atoms, in particular of 1 to 15 carbon atoms and, in particular, from 1 to 10 carbon atoms.
• alkenyl group is meant, in the context of the present invention, an alkenyl group linear, branched or cyclic, optionally substituted, from 2 to 20 carbon atoms, in particular from 2 to 15 carbon atoms and, in particular, from 2 to 10 carbon atoms.
• alkoxy group is meant, in the context of the present invention, an oxygen atom substituted by an alkyl as defined above.
• aryl group is meant, in the context of the present invention, an optionally substituted aromatic or heteroaromatic, mono- or polycyclic group having from 6 to 20 carbon atoms, in particular from 6 to 14 carbon atoms, in particular, from 6 to 8 carbon atoms.
• the heteroatom (s) likely to be present in the aryl group is (are) advantageously chosen from the group consisting of N, O, P or S.
• each ring may comprise from 3 to 8 carbon atoms.
• aryloxy group is meant, in the context of the present invention, an aryl-substituted oxygen atom as previously defined.
• carboxylic group is meant in the context of the present invention, a group of formula -COOH.
• optionally substituted is meant, in the context of the present invention, a radical substituted with one or more groups selected from a group containing one or more heteroatoms, such as N, O, F, Cl, P, Si, Br or S; an alkyl group; an alkoxy group; a halogen; a hydroxy; a cyano; trifluoromethyl; a carboxylic group or a nitro.
• halogen is meant, in the context of the present invention, a fluorine, a chlorine, a bromine or an iodine.
• diazonium salt known to those skilled in the art can be used to prepare the diazonium salt derivative used in the process according to the present invention.
• the diazonium salt is an aryl diazonium salt and in particular an aryl diazonium salt of formula (I): R 6 -N 2 + , A " (I) in which:
• Re represents an aryl group as previously defined.
• R 6 is preferably chosen from aryl groups substituted with electron-withdrawing groups such as NO 2 , COH, ketones, CN , CO 2 H, NH 2 (as NH 3 + ), esters and halogens.
• Particularly preferred aryl groups Re are nitrophenyl, benzoic acid, methyl benzoate and bromophenyl.
• A may especially be chosen from inorganic anions such as halides such as I ⁇ , Br “ and Cl " , haloborates such as tetrafluoroborate, perchlorates and sulfonates and organic anions such as alcoholates, carboxylates.
• inorganic anions such as halides such as I ⁇ , Br “ and Cl "
• haloborates such as tetrafluoroborate, perchlorates and sulfonates
• organic anions such as alcoholates, carboxylates.
• the preparation of the diazonium salt derivative used in the context of the present invention is advantageously carried out before carrying out the process according to the invention.
• the process comprising the following steps consisting of: i) dissolving the diazonium salt as previously defined to form a So solution; ii) bringing the So solution into contact with a compound C as previously defined; iii) bringing the mixture obtained in step (ii) under conditions allowing the formation of a diazonium salt derivative and thus obtaining an Si solution.
• the solution S0 comprises, as a solvent, a polar solvent, preferably this one will be protic.
• polar solvent is meant, in the context of the present invention, a solvent which has a high dielectric constant, generally it is greater than 7 and preferably 15.
• protic solvent is meant, in the context of the present invention, a solvent which comprises at least one hydrogen atom capable of being released in the form of a proton.
• the protic solvent is advantageously chosen from the group consisting of water, deionized water, distilled water, acidified or basic water, acetic acid, hydroxylated solvents such as methanol and ethanol, and low glycols. molecular weights such as ethylene glycol, and mixtures thereof.
• the protic solvent used in the context of the present invention consists only of a protic solvent or a mixture of different protic solvents.
• the protic solvent or the mixture of protic solvents may be used in admixture with at least one aprotic solvent, it being understood that the resulting mixture has the characteristics of a protic solvent.
• Water, preferably distilled and / or deionized is the preferred protic solvent.
• aprotic solvent is meant, in the context of the present invention, a solvent which is not considered as protic. Such solvents are not likely to release a proton or accept one under non-extreme conditions.
• the aprotic solvent is advantageously chosen from dimethylformamide (DMF), acetone, acetonitrile and dimethyl sulfoxide (DMSO).
• the solvent may correspond to an organic acid, a sulfoxide or an alcohol as defined above.
• a variant of step (i) consists of preparing the diazonium salt in situ.
• a diazonium salt can be prepared from a precursor of said diazonium salt.
• precursor of the diazonium salt it is necessary to understand a molecule separated from the diazonium salt by a single operating step and easy to implement.
• an amino aryl which may contain several amino substituents, which gives an aryl diazonium salt by reaction with NaNO 2 in acidic medium.
• step (ii) compound C is typically added in excess relative to the diazonium salt.
• concentration of compound C 50 times, in particular 20 times, in particular, 10 times and, more particularly, 5 times greater than the concentration of the diazonium salt in the So solution.
• the conditions allowing the formation of a diazonium salt derivative from a diazonium salt and a compound C generally correspond to the mere placing in the presence of the reaction partners in the reaction medium. It is preferable to use an excess of compound C.
• a diazonium salt RC 6 H 4 -N 2 + is added to an organic acid or its salt, such as acetic acid CH 3 -COOH, it seems that the diazonium salt reacts with the acid to form an ester compound such as RC 6 H 4 -N 2 -O-CO-CH 3 in the case of acetic acid.
• ester compound such as RC 6 H 4 -N 2 -O-CO-CH 3
• diazonium ester is demonstrated by the stabilization of the diazonium reagent. Indeed, the diazonium salts decompose rapidly in aqueous solutions, forming an orange precipitate. In contrast, solutions of diazonium salts in the presence of an excess of acidic compounds such as acetic acid are colorless or yellow and remain clear and stable for several days.
• the preferred sulfoxides are those for which R 4 and R 5 are identical or different alkyl groups.
• reaction temperature is generally less than 50 ° C., in particular less than 40 ° C. and more particularly less than 30 ° C.
• temperature during step (iii) is the ambient temperature.
• ambient temperature is meant a temperature of 20 ° C. ⁇ 5 ° C.
• the preparation of the diazonium salt derivative is carried out in an acid medium.
• an acid medium in the context of the present invention, in the presence of an inorganic acid, in particular chosen from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and hydrofluoric acid, in an amount between 10 ⁇ 4 and 1 M, advantageously between 10 ⁇ 3 and 0.6 M and, in particular, between 10 "2 and 0.4 M.
• an inorganic acid in particular chosen from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and hydrofluoric acid, in an amount between 10 ⁇ 4 and 1 M, advantageously between 10 ⁇ 3 and 0.6 M and, in particular, between 10 "2 and 0.4 M.
• this step consists of subjecting, in the presence of carbon nanotubes (m-SWNT and sc-SWNT), the diazonium salt derivative to non-electrochemical conditions allowing the formation of at least one radical entity from said derivative. .
• the formation of this radical entity is in the absence of the application of any electrical voltage at the nanotubes or in the reaction mixture.
• radical chemical grafting refers in particular to the use of molecular entities derived from the diazonium salt derivative having an unpaired electron, or capable of producing, in order to form covalent link bonds with the surface. of nanotubes.
• the grafting step uses a solution S2 which comprises the carbon nanotubes and the diazonium salt derivative (also called in the present "reaction mixture").
• This solution S2 comprises, as a solvent, a polar solvent, preferably a protic solvent as defined above.
• the non-electrochemical conditions allowing the formation of at least one radical entity from the diazonium salt derivative in the grafting step of the process of the present invention are conditions which allow the formation of radical entities from the derivative of diazonium salt. These conditions involve parameters such as, for example, the temperature, the nature of the solvent, the presence of a particular additive, stirring, the pressure while the electric current does not occur during the formation of radical entities.
• radical entities are numerous and this type of reaction is known and studied in detail in the prior art. It is thus possible, for example, to act on the thermal, kinetic, chemical, photochemical or radiochemical environment of the diazonium salt derivative in order to destabilize it so that it forms a radical entity. It is of course possible to act simultaneously on several of these parameters.
• the non-electrochemical conditions allowing the formation of radical entities during the grafting step according to the invention are typically chosen from the group consisting of thermal, kinetic, chemical, photochemical and radiochemical conditions. their combinations.
• the conditions used as part of the grafting step of the process according to the present invention are the kinetic conditions.
• the thermal environment is a function of the temperature. Its control is easy with the heating means usually employed by those skilled in the art.
• the use of a thermostated environment is of particular interest since it allows precise control of the reaction conditions.
• the kinetic environment essentially corresponds to the agitation of the system and the friction forces. It is not a question here of the agitation of the molecules in itself (elongation of bonds, etc.), but of the global movement of the molecules.
• the application of a pressure or the stirring of the reaction mixture makes it possible in particular to supply energy to the system so that the diazonium salt derivative is destabilized and can form reactive radical species.
• the solution S2 is subjected to mechanical stirring and / or ultrasonic treatment.
• the suspension implemented during the grafting step is subjected to a high rotational speed by means of a magnetic stirrer and / or a magnetized bar and this, for a period of time between min and 10 h stirring, especially between 10 min and 5 h and, in particular, between 15 min and 4 h.
• the suspension implemented during the grafting step is subjected to ultrasonic treatment, in particular by using an ultrasonic tank, typically with an absorption power of 500 W and at a frequency of 25. or 45 kHz and this, for a period of between 5 min and 10 h stirring, especially between 15 min and 8 h and, in particular, between 30 min and 5 h.
• one (or more) chemical initiator (s) is used in the reaction medium.
• the presence of chemical initiators is often coupled with non-chemical environmental conditions as discussed above.
• a chemical initiator whose stability is less than that of the diazonium salt derivative under the selected environmental conditions will evolve into an unstable form which will act on the diazonium salt derivative and will generate the formation of radical entities from this last.
• chemical initiators whose action is not essentially related to environmental conditions and which can act over wide ranges of thermal or kinetic conditions.
• the initiator will preferably be adapted to the environment of the reaction, for example to the solvent employed.
• BusSnH and I 2 belong to photochemical or radiochemical initiators; essentially chemical initiators, this type of initiators acting rapidly and under normal conditions of temperature and pressure on the diazonium salt derivative to enable it to form radicals.
• Such initiators generally have a redox potential which is less than the reduction potential of the diazonium salt derivative used in the reaction conditions.
• it can thus be for example a reducing metal, such as iron, zinc, nickel; a metallocene; an organic reducing agent such as hypophosphorous acid (H3PO2) or ascorbic acid; of an organic or inorganic base in proportions sufficient to allow destabilization of the diazonium salt derivative.
• the reducing metal used as a chemical initiator is in finely divided form, such as wool (also known more commonly as "straw") metal or metal filings.
• wool also known more commonly as "straw"
• a pH greater than or equal to 4 is usually sufficient.
• Radical reservoir-type structures such as polymer matrices previously irradiated with an electron beam or with a heavy ion beam and / or with all the irradiation means mentioned above, can also be used as chemical initiators for destabilizing the diazonium salt derivative and leading to the formation of radical entities from the latter.
• the grafting step of the process according to the present invention is carried out in particular at a temperature of less than 50 ° C., in particular less than 40 ° C. and, more particularly, less than 30 ° C.
• the temperature during heating The grafting step is the ambient temperature.
• the carbon nanotubes are present in the solution S2 in an amount of between 1.10 5 and 1 g / l, in particular between 1.10 -4 and 1.10 1 g. / L and, in particular, between 1.10 ⁇ 3 and 5.10 "2 g / L of solution S 2 .
• the solution S 2 can comprise a single diazonium salt derivative or a mixture of at least two, in particular at least three and even at least four derivatives. of different diazonium salt.
• the amount of derivative (s) of the diazonium salt in the solution S 2 is between 1.10 "7 and 1.1 CT 1 M, especially between 1.10" 6 and 1.10 "2 M and in particular between 1.10" 5 and 1.10 " 3 M.
• the grafting step according to the process of the present invention can be stopped before all the radical entities derived from the diazonium salt derivatives are preferentially attached to the m-SWNTs.
• the method of the present invention comprises the successive steps of: a) providing a solution S3 comprising a mixture of m-SWNT and sc-SWNT in contact with at least one diazonium salt derivative; b) reacting, by radical chemical grafting, said diazonium salt derivative on said mixture of m-SWNT and sc-SWNT according to the grafting step as defined above; c) optionally, purifying the grafted m-SWNTs and / or sc-SWNTs.
• the process of the present invention comprises the successive steps of: a) providing a solution S3 comprising a mixture of m-SWNT and sc-SWNT in contact with at least one diazonium salt derivative; b) grafting, by radical chemical grafting, said diazonium salt derivative onto said mixture of m-SWNT and sc-SWNT according to the grafting step as defined above so as to obtain a mixture of grafted m-SWNTs and non-grafted sc-SWNT; c) optionally, purifying grafted m-SWNTs and / or non-grafted sc-SWNTs based on the differential chemical and / or physical properties caused by said grafting.
• the separation method according to the present invention includes a method for distinguishing m-SWNT from sc-SWNT in the same mixture. For this reason, in the process according to the invention, the purification step (c) is optional.
• the m-SWNT / sc-SWNT ratio in the carbon nanotube mixture used during step (a) of the process according to the invention is variable and can in particular depend on the conditions used during the preparation of these nanotubes.
• step (a) of the process according to the invention typically the SWNT nanotubes are present in the solution S3, in an amount of between 1.1CT 5 and 1 g / 1, in particular between 1.1CT 4 and 1.1 CT 1 g / 1 and, in particular, between 1.10 "3 and 5.10 " 2 g / 1 of solution S 3 .
• the solution S3 contains, as a solvent, a polar solvent, preferably a protic solvent as defined above.
• solution S3 may further comprise a dispersing agent.
• a dispersing agent makes it possible to solubilize the mixture of carbon nanotubes used in the context of the present invention and to maintain it in the form of a stable suspension.
• stable suspension is meant in the context of the present invention a suspension in which the nanotubes do not sediment or little sediment to the eye and remain in suspension for a few minutes, for a few hours, for several days or for several weeks.
• Any dispersing agent known to those skilled in the art can be used in the context of the solution S3 and in particular any agent known to disperse lipids or proteins in aqueous solutions.
• dispersing agents used to prepare stable solutions of nanotubes are chosen from the group consisting of natural and synthetic detergents and surfactants. More particularly, the dispersing agent used in the context of the present invention is chosen from the group consisting of poloxamers such as poloxamer F127 and polyoxyethylene sorbitol esters such as those marketed under the trademark TWEEN® or EMASOL TM .
• the dispersing agent is present in the solution S3 in an amount of between 0.1 and 10%, especially between 0.5 and 7% and, in particular, between 1 and 4% by weight relative to the mass of solution. S3.
• the solution S2 in which the grafting step is carried out can correspond to the solution resulting from the mixing of the solution S3, which contains the mixture of nanotubes sc-SWNT and m-SWNT. , and Si solution, in which the diazonium salt derivative was prepared.
• these three solutions contain the same solvent, especially the same polar solvent, preferably protic and, in particular, distilled water.
• the amounts of solution S3 containing the nanotubes and Si solution containing diazonium salt derivative used are variable.
• the solution ratio Ss / Si solution is between 99/1 and 1/99, in particular between 95/5 and 5/95 and, in particular, between 90/10 and 10/90.
• Step (a) of the process according to the present invention is especially carried out at a temperature of less than 50 ° C., in particular less than 40 ° C. and, more particularly, less than 30 ° C.
• the step ( a) the process according to the present invention is carried out at room temperature.
• the chemical and / or physical properties of the m-SWNTs can be modified by the reaction with the diazonium salt derivatives, whereas the sc-SWNTs are preserved. thanks to the selective and specific nature of said grafting.
• the mixture of grafted m-SWNTs and sc-SWNTs can be considered as a source of "pure" sc-SWNTs. Such a mixture can, therefore, be used in electronic devices and in particular in the manufacture of transistors.
• Step (c) of the process according to the present invention aims at using the selective and specific character of the grafting of the diazonium salt derivative on m-SWNTs and the chemical and / or differential physical properties caused by said grafting.
• Step (c) of the process according to the present invention can implement at least one technique selected from separation techniques based on chemical affinity, filtration, centrifugation, electrophoresis and / or chromatography.
• nanotubes without polymer ie sc-SWNT can be precipitated.
• the experimental part proposes a method of separation of grafted m-SWNTs and sc-SWNTs. This process is based on a reduction by tin dichloride of the NO2 grafted onto m-SWNTs.
• the carbon nanotubes may undergo a treatment, in particular to remove the metal particles of catalyst and the carbon used during this preparation.
• a treatment in particular to remove the metal particles of catalyst and the carbon used during this preparation.
• the method below makes it possible to obtain suspensions of carbon nanotubes with a good quality or even greater than the suspensions prepared by the techniques of the state of the art.
• This method comprises a treatment of the mixture of sc-SWNT and m-SWNT with nitric acid and a size exclusion chromatography of the mixture of sc-SWNT and m-SWNT following treatment with nitric acid. It is It is also possible to apply ultrasound treatment before, during and / or after exposure to nitric acid.
• the process for treating SWNT prior to the separation process comprises the successive steps of: i ') contacting a suspension of a mixture of m-SWNT and sc-SWNT with a solution containing nitric acid; ii ') heating the solution obtained in step (i') and then cooling it; iii ') filtering the solution obtained in step (ii') and suspending the filtrate in a basic pH solution; iv ') filtering the suspension obtained in step (iii') and suspending the filtrate in a solution containing a dispersing agent as previously defined; v ') submit the resulting solution to step
• the preparation of the different suspensions used in this process and step (ii ') are subjected to agitation.
• Any mechanical technique for dispersing and suspending carbon nanotubes can be used for this purpose. Examples of such techniques include manual agitation, ultrasonic treatment, mechanical agitation or a combination of such techniques. These techniques may require the use of a magnetic stirrer and a bar magnet, an ultrasonic bath or a mechanical stirrer with rods, blades, propellers, etc. These mechanical stirring techniques for dispersion can last from 1 to 30 minutes, in particular from 2 to 15 minutes. It is also possible to heat, typically around 80 0 C, the medium.
• the application of ultrasonic treatment and heating cycles for example 5 to 20 cycles, preferably 10, over a period of 12 to 36 hours, preferably 24 hours, makes it possible to obtain very satisfactory dispersions.
• the solution containing nitric acid typically comprises, as a solvent, a protic solvent as previously defined.
• Nitric acid is generally present in this solution in an amount of between 20 and 70%, especially between 30 and 60%, in particular between 40 and 50% and, more particularly, of the order of 45% (ie 45%). % ⁇ 3%).
• the suspension of nanotubes is advantageously prepared in a solution comprising, as solvent, a protic solvent as defined above.
• the amount of nanotubes in this solution is between 0.5 and 100 g / l, especially between 0.5 and 50 g / l and, in particular, of the order of 1 g / l of suspension (ie 1 g / L ⁇ 0.5 g / L).
• the volume ratio (solution containing nitric acid) / (suspension of nanotubes) is typically between 10 / 0.1 and 10/10, in particular between 10 / 0.5 and 10/5 and, in particular, from about 10/1.
• Stage (ii ') generally consists, first of all, in bringing the mixture of nanotubes and nitric acid to reflux.
• This sub-step typically lasts 1 hour at 12 h, in particular from 2 h to 6 h and, in particular, of the order of 4 h (ie 4 h ⁇ 30 min).
• Any technique known to those skilled in the art for cooling a liquid can be used to cool the mixture after this heating sub-step.
• the cooled mixture obtained after step (ii ') is filtered by any filtration technique known to those skilled in the art and, in particular, by using a filtration membrane such as a hydrophilic polypropylene filtration membrane advantageously of porosity of 0.45 ⁇ m.
• the sodium hydroxide solution used in step (iii ') comprises, as a solvent, a protic solvent as defined above.
• the solution is preferably buffered to a basic pH generally greater than 8 and advantageously to 10.
• the buffer may be made with different salts such as hydroxides and carbonates of sodium and potassium.
• sodium hydroxide is present in this solution in an amount of between 1.1 CT 2 and 10 g / L, in particular between 1.10 -1 and 1 g / L, and in particular of the order of 0.5 g. / L of solution
• Step (iii ') can be repeated several times and as long as the filtrate is gray.
• Step (iv ') consists in putting the last filtrate in a solution containing a dispersing agent as defined above.
• This solution generally comprises, as a solvent, a protic solvent as defined above.
• the dispersing agent is present in this solution in an amount of between 0.1 and 10%, especially between 0.5 and 7% and, in particular, between 1 and 4% by weight relative to the mass of this solution.
• the solution containing the nanotubes and the dispersing agent is heated to a temperature greater than 40 ° C., in particular greater than 50 ° C. and, in particular, of the order of 70 ° C. (ie 70 ° C. ⁇ 10 ° C.) and this at least twice, advantageously three times.
• step (v ') of the process Any size exclusion chromatography technique known to those skilled in the art and any suitable equipment for this technique can be used during step (v ') of the process.
• the present invention also relates to a mixture of m-SWNT grafted and sc-SWNT obtainable following step (b) of a method as defined above.
• the present invention also relates to a kit for separating m-SWNTs and sc-SWNTs contained in a mixture.
• such a kit comprises in particular: ⁇ ) in a first compartment, a solution containing at least one diazonium salt derivative as defined above, ⁇ ) in a second compartment, a solution containing at least one agent capable of stop the reaction, by chemical grafting radical, diazonium salt derivative on m- SWNT and sc-SWNT.
• the latter comprises in particular: ⁇ ') in a first compartment, a diazonium salt as defined above or one of its precursors as defined above; ⁇ ') in a second compartment, a compound C selected from the group consisting of an organic acid, a sulfoxide, an alcohol and a salt thereof, as previously defined;
• the agent capable of stopping the radical chemical grafting reaction of the diazonium salt derivative is advantageously chosen from pH modifiers and complexing or reactive agents with the diazonium salt derivative, such as optionally substituted naphthol.
• the two kit variants according to the invention may comprise at least one other compartment in which there will be at least one element selected from the group consisting of a mixture of m-SWNT and sc-SWNT, a dispersing agent, a usable solution to purify the mixture of m-SWNT and sc-SWNT prior to the process according to the invention, a solution for transforming the salt precursor diazonium salt and a solution that can be used in at least one step of the process according to the invention.
• Figure 1 shows the evolution of the SWNT reaction (Nanoledge, 18 mg / L) with BrBDT in a 2% aqueous solution of F127 at 27 ° C. Thin lines: Spectra recorded at 15 sec, 7 min, 14 min,
• Thick line Baseline of the complete reaction.
• Figure 2 shows the determination of peak heights for m- and sc-SWNT at 688 and 940 nm respectively (marked by arrows) from the baseline-corrected spectra of the complete reaction, in the SWNT reaction ( Nanoledge,
• Figure 3 shows the determination of the M vs SC selectivity in the reaction of BrBDT (5 mM) with SWNTs (57 mg / L) in a 2% aqueous solution of F127.
• the relative height of the peak at 940 nm (sc-SWNT) is represented as a function of the relative height of the peak at 688 nm (m-SWNT).
• Selectivity is defined as the inverse of the slope (2.8 in this case).
• Figure 4 shows the stop of the reaction and the recovery of functionalized SWNTs.
• the relative height of the peak of m-SWNT (*) and sc-SWNT (o) is plotted as a function of time during the reaction of SWNTs (18 mg / L) with BrBDT (1 mM) in an aqueous solution.
• 2% F127 800 ⁇ L.
• 80 ⁇ l of a 50 mM solution of 2-naphthol is added, followed by 2.4 ml of ethanol.
• the solution is filtered and the residue suspended in 800 ⁇ l of a 2% aqueous solution of F127 (relative peak heights marked by a square).
• FIG. 5 shows a comparison of the M vs Sc selectivity in the SWNT reaction with a diazonium salt or a diazonium salt derivative.
• the relative height of the peak at 940 nm is plotted against the relative height of the peak at 688 nm.
• the SWNTs 21 mg / L are incubated either with 100 ⁇ M of NO 2 BDT (D) or with 100 ⁇ M of NO 2 BDT preincubated with 50 mM of trifluoroacetic acid for 1, 10 or 30 minutes ( *, •, o respectively).
• FIG. 5B the SWNTs (12 mg / L) are incubated with either 5 mM BrBDT (0) or with 5 mM BrBDT in the presence of 500 mM ammonium acetate (*).
• Figure 6 shows a histogram representation of the M vs Sc selectivity in the SWNT reaction with either diazonium salts (gray rectangles) or diazonium salt derivatives (black rectangles).
• the SWNTs reacted in a 2% aqueous solution of F127, either with a salt of diazonium alone, either with a diazonium salt and an acid compound, with or without incubation, as described in columns 1 to 5 of Table 1.
• the selectivity is calculated as described in Figure 3, with the adjustment parameters at line as given in columns 7 and 8 of Table 1 below.
• Figure 7 shows the separation of m-SWNT and sc-SWNT.
• Figures 7A and 7B are the absorption spectra (absorption as a function of wavelength in nm) of SWNT fractions after enrichment in sc-SWNT: supernatant ( Figure 7A) and pellet (Figure 7B). Baselines for m-SWNT peaks (600-700 nm) and sc-SWNT peaks (750-1200 nm) are shown in broken lines.
• Figure 7C shows the absorption peaks of the SWNTs as a function of the incident light energy (eV) for the supernatant fractions (dashed line) and the pellet (solid line).
• eV incident light energy
• the baseline is subtracted from the peak spectrum and the resulting curve is plotted against the energy of the incident light.
• the area under the curve is calculated for each peak and the curves are renormalized by the peak area of m-SWNT (1.7-2.05 eV).
• the sc-SWNT / m-SWNT peak ratios are 40 and 64 for the supernatant and pellet, respectively.
• SWNT solutions Single-wall carbon nanotubes (SWNT) are purified by nitric acid treatment for removing the catalyst metal particles and the amorphous carbon and then size exclusion chromatography to remove the remaining amorphous carbon particles.
• SWNT Single-wall carbon nanotubes
• One hundred mg of crude SWNT (purchased from Nanoledge, France) is suspended in 10 mL of pure water by ultrasonic bath treatment (80 W, 45 kHz, peak power) for 30 min.
• the suspension is diluted in a mixture of 70 ml of 65% concentrated nitric acid and 30 ml of pure water. The whole is refluxed for 4 h with magnetic stirring.
• the suspension was then cooled in an ice bath, diluted by the addition of 110 ml of ice-cold pure water and then vacuum-filtered on a hydrophilic polypropylene filtration membrane with a porosity of 0.45 ⁇ m (PALL membranes, USA).
• the filter residue is resuspended in sodium hydroxide solution (100 mg NaOH in 200 mL of pure water) by a 2 min treatment in an ultrasonic bath (same conditions as above), then filtered. again (same conditions as above).
• the residue is rinsed with the sodium hydroxide solution until the filtrate is gray. Then it is rinsed with some pure water and stored wet in a closed container.
• One quarter of the black residue is suspended in 20 ml of F127 poloxamer solution (2% by weight in pure water), and treated with 3 cycles of heating at 70 ° C. followed by 10 minutes in an ultrasonic bath.
• the solution is then purified by size exclusion chromatography on a Sephacryl S400 column (GE Healthcare, France) 4 cm in diameter and 2.5 cm in height.
• SWNTs are elected with a solution of F127 at 2% in pure water heated at 50 ° C.
• the fractions of the first dark peak are collected and used as stock solution of SWNT.
• the concentration and purity of the SWNT solutions are tested by absorption spectroscopy.
• the purity is estimated from the ratio of the peak height at 940 nm (determined according to the protocol described in the following paragraph) and the absorbance at 940 nm. This ratio is greater than or equal to 0.4 for good purity.
• nanotubes have been pretreated. This consists of subjecting the carbon nanotubes to ultrasound in solution in concentrated nitric acid. It could be done on the SWNT before and after the purification.
• concentration of nitric acid varied from 30% to 65% in water.
• the optimal duration of ultrasound exposure depends on the power of the ultrasonic bath used and the concentration of nitric acid. The following example gives typical conditions:
• Raw SWNTs (9.4 mg, Nanoledge source, diameters 1.2-1.4nm) were dissolved in 10 mL of concentrated nitric acid (65% in water) and then placed in an ultrasonic bath (8OW, 45kHz, power maximum) for 20 minutes.
• the treatment can be activated by adding iron straw (20mg), the iron straw is then removed after exposure to ultrasound using a magnetic bar.
• Distilled water (15 mL) was then added and the suspension filtered under vacuum on a PTFE (polytetrafluoroethylene) filter with a porosity of 0.2 ⁇ m previously wet with ethanol. The residue was rinsed three times with 20 mL of distilled water and the black filter kept wet.
• the nanotubes were then refluxed in nitric acid and exclusion chromatography was performed.
• the diazonium salts used are nitrobenzenediazonium tetrafluoroborate (NO 2 BDT), bromobenzenediazonium tetrafluoroborate (BrBDT) and methoxybenzenediazonium tetrafluoroborate (MeOBDT).
• the acids used to form a diazonium salt derivative are acetic acid, ammonium acetate, trifluoroacetic acid, para-toluenesulfonic acid, lactic acid, propylphosphonic acid, oxalic acid.
• Dimethylsulfoxide (DMSO) was used as the sulfoxide and methanol and ethanol as alcohol.
• the control compounds are hydrochloric acid and sodium hydrogencarbonate.
• the reaction of the SWNTs with the diazonium is followed in a quartz tank by absorption spectroscopy, for wavelengths between 320 and 1250 nm.
• the diazonium salt is dissolved in pure water at a concentration 10 times higher than the desired concentration.
• the acid, the sulphoxide or the alcohol are added in excess by at least 50 and the The solution is left for 10 min preincubation at room temperature to allow complete formation of the diazonium salt derivative.
• 80 ⁇ L of this solution are added to the quartz tank with 720 ⁇ L of SWNT solution in F127 2% in pure water (usually 24 mg / L of SWNT, ie 2 mM of carbon atoms of SWNT) .
• the absorption spectra of the solution are recorded for 2 h.
• a sample of SWNT solution is contacted with a large amount of nitrobezenediazonium tetrafluoroborate until the characteristic peaks of SWNTs disappear from the absorption spectrum.
• the reaction is stopped by adding naphthol (80 ⁇ l of a solution of 50 mM naphthol in an aqueous solution of F127 at 2%) and incubated for 10 min.
• the solution is then poured into 10 ml of ethanol to precipitate the SWNT, vacuum filtered on a polytetrafluoroethylene membrane with a porosity of 0.2 ⁇ m and rinsed with ethanol and with pure water.
• the residue is taken up in 800 ⁇ l of 2% aqueous F127 solution and treated with an ultrasonic bath (80 W, 10 min).
• the absorption spectrum of these SWNTs after complete reaction is then used as the "background spectrum" of the SWNTs and deduces spectra for the measurement of the height of the peaks.
• the height of the peaks is determined from the spectra whose background spectrum of the SWNTs was deduced. A baseline tangent to this curve at the low points adjacent to the peak to be measured is plotted, as shown in Figure 2 to account for the drift of the background during the reaction. The height of the peak is measured as the difference between the curve and the line tangent to the maximum absorption wavelength.
• the height of the peak relative to a time t being the height of the peak at t divided by the height of the initial peak.
• the selectivity of the reaction is defined on the graph of the relative height of the semiconductor peak (at 940 nm) plotted as a function of the relative peak height of the metals (at 688 nm), as shown in FIG. graph gives a straight line independent of the SWNT and diazonium concentration and whose inverse of the slope is the selectivity. It ranges from 2 to 4 in the case of the reaction of aryl diazonium tetrafluoroborate with SWNTs (MeOBDT, BRBDT, NO 2 BDT).
• the reaction can be stopped by the addition of an excess of naphthol (typically 100 ⁇ l of a 50 mM naphthol solution with 2% F127 in water) and the diazonium salt and the sodium salt derivative.
• diazonium are removed by precipitation of SWNT by adding 2 volumes of ethanol and filtration under vacuum. The relative height of the peaks is maintained after the stop reaction and the filtration (FIG. 4, data framed by squares).
• the pretreated SWNTs have a selectivity of 6.6 and 8.4 (without or with activation by iron straw, respectively) after reaction with 2 mM Br-BDT + 500 mM ammonium acetate. ⁇ -J OO
• a solution of 1 mM nitrobenzenediazonium tetrafluoroborate and 0.5 M trifluoroacetic acid and 2% F127 in pure water is prepared and incubated at room temperature for 10 minutes. 1.9 ml of this mixture is added to 17 ml of aqueous solution of SWNT at 24 mg / l and F127 2% and the whole is kept under magnetic stirring for one hour at room temperature. Two ml of aqueous solution of 50 mM naphthol and 2% F127 are added and, after 10 min of incubation, the mixture is precipitated by adding 40 ml of ethanol, filtered under vacuum (porosity 0 tetrafluoroethylene filter, 45 ⁇ m). The residue is rinsed with ethanol and with pure water.
• the residue is dissolved in 10 mL of 2% aqueous F127 solution in an ultrasonic bath.
• the suspension is then centrifuged for 20 min at 1000 g.
• the supernatant is separated and the pellet rinsed two twice with an aqueous solution of F127 at 2%.
• the rinsed pellet is dissolved in 10 ml of this solution and the absorption spectra of the supernatant and the pellet are measured and compared (FIG. 7).
• the supernatant enriched in m-SWNT and the pellet in sc-SWNT As shown from the peaks and following the subtraction of the background spectrum, the supernatant enriched in m-SWNT and the pellet in sc-SWNT. Indeed, the peak sc-SWNT / peak m-SWNT ratio is 40 in the supernatant and 64 in the pellet. Due to the selective reactivity of diazonium salt derivatives with m-SWNTs rather than sc-SWNTs, a fraction enriched
• Patent Application JP 2007 031238 (Sony

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