ES2324810A1 - Composition of polymers and carbon nanotubes, method for producing same and the uses thereof - Google Patents

Abstract

Composition of carbon nanotubes and polymer that can be obtained by means of a method that comprises: sonication of a dispersion of carbon nanotubes in an acid solvent the addition of monomers to the nanotube dispersion and the rapid addition of a radical initiator to the previous dispersion of nanotubes and monomer, the resulting mixture being maintained at a temperature of between 0 C and 40 C. The method is implemented with continuous sonication. Not only said composition but also the dispersion thereof in water are useful as components in paints, dyes, printing processes, electronic devices or circuits or in bioapplications.

Description

Composition of polymers and carbon nanotubes,  procurement procedure and its uses.

Object

The present invention relates to a process of in situ polymerization of monomers, more preferably aniline, in the presence of carbon nanotubes. In addition, it refers to the composition obtained by said process, which comprises a polymer, preferably fibrillary polyaniline, and carbon nanotubes, and its different uses. This composition is soluble and stable in water.

Prior art

Intrinsic Conductive Polymers (PCs), also called electroactive polymers or synthetic metals, it They have known for a long time. Examples of these PCs are polyacetylene, polypyrrole, poly (paraphenylene), polythiophene and its derivatives. PCs have electrical, magnetic and optical properties of a metal while having usually associated mechanical properties to conventional polymers. They have great potential for applications for the development of plastic electronics (circuits flexible, transistors, sensors, light emitting diodes organic, photovoltaic cells, actuators, etc.), as well as in corrosion and material protection applications functional textiles Its conductive properties are due to the doped form of the polymer, and this doping can be performed Chemical or electrochemical. In their conductive form, these materials they have limited use for technological applications, since they are, often, chemically unstable, and virtually intractable, being hardly processable in solution or in molten.

Among PCs, polyaniline (PANI) has a Special relevance It is chemically stable and conductive of protonated electricity. In addition, in recent years they have described ways to solubilize it in conventional solvents, what which offers the possibility of being used using techniques usual to form coatings, films, fibers, patterns printed, etc.

The polyaniline polymer can be presented in various general forms, including the so-called reduced form (leuco-emeraldine base), the partially oxidized called the base form emeraldine and the pernigraniline form, completely oxidized Each oxidation state can occur in the form of its base or in protonated form (salt) by means of treatment of the base with an acid. Electrical properties and PANI optics vary with different oxidation states, and The different ways.

The emeraldine form of PANI is of great interest for the aforementioned applications, especially because of its conversion properties of the insulating emeraldine base form soluble to the conductive and non-soluble emeraldine salt. There are several chemical synthesis routes described in the literature, mostly based on acid doped. The non-conductive form of PANI, emeraldine base, is soluble in strong polar solvents such as N-methyl pyrrolidone (NMP), while the conductive form of PANI, emeraldine salt, is soluble only in very acidic acids.
powerful.

Recently, a process for obtaining PANI in fibrillar form by rapid addition of the polymerizing oxidizing agent to the aniline monomer in a single stage has been described (Huang J., et al ., 2006, Chem. Commun . Vol. 4 pp. 367-376 ). The fibrillar character also improves the solubility of the resulting emeraldine in aqueous solutions.

There is a remarkable interest in finding a way to improve the conductivity of PANI while retaining its thermal stability and processability. It is also known in the literature that is possible the combination of PANI with certain carbonaceous materials such as carbon nanotubes.

Carbon nanotubes (CNTs) are objects in the relatively new nanoscale, consisting of one or more rolled graphene sheets forming cylindrical structures for give rise to what is called single wall nanotubes (SWNT of the English single-walled carbon nanotubes) and nanotubes multi-wall (MWNT of English multiwalled carbon nanotubes). CNTs possess structural, mechanical, thermal properties, electronic, and unique optical and are of great interest in applications in several fields of high technological interest such as nanoelectronics, field emission, devices nanoelectromechanics, sensors, composites or plastics functional.

For many applications, especially for the manufacture of functional plastics composites, is desirable to be able to disperse CNTs and maintain such dispersions to achieve a good homogeneity of the product, minimize processing problems and improve their quality.

There are composite materials with PANI and CNT that were obtained by means of dispersion methods of CNT /
PANI applying the appropriate treatment to CNTs and their use in insulating polymers. The process is based on a mixture of the two constituents CNTs and PANI through an ex situ approach . This type of material could be used in electronic circuit printing.

On the other hand, in 2001 a process of in-situ polymerization of aniline in nanotubes was described, to obtain the first PANI / CNTs composite material, and the process of transfer of charge between nanotubes and polyaniline through selective interactions. These procedures were carried out at temperatures of about -3 ° C (Cochet, M. et al ., 2001, Chem. Commun ., Vol. 16, pp. 1450-1451).

Subsequently, the manufacture of a highly functional soluble CNT / PANT composite material at temperatures below 0 ° C was described (In het Panhuis M., et al ., 2005, J. Phvs. Chem. B , vol. 109, pp. 22725 -22729). This composite, consisting of polyaniline in its base form and carbon nanotubes, was soluble in NMP (N-methyl-2-pyrrolidinone). The composite material, PANI / CNTs, in powder had conductivity both in its base form and salt, giving conductivity values at room temperature of approximately 1 S / cm, conductivity that was determined by the percolation network of the nanotubes in the composite material .

Explanation of the invention.

The present invention describes an in-situ polymerization process of monomers, preferably aniline, on carbon nanotubes, obtaining a composite material (fibrillar polyaniline salt in its conductive form (emeraldine) and carbon nanotubes) with nanotube contents of up to even more. 50% by weight (up to 70% by weight), which is highly dispersible and stable in aqueous solutions. In addition, the invention relates to aqueous dispersions of this composition. Likewise, the material obtained is an electrical conductor, has better thermal stability than the polyaniline salt without nanotubes and is fluorescent.

A combination of reaction conditions is involved in the production of these materials, such as ultrasonic irradiation of the dispersions, the controlled temperature in an in situ polymerization of aniline in the presence of nanotubes, the rapid addition of the oxidant, in addition, the nanometric size of these nanotube structures also allows the compositions of the present invention to be highly dispersible and stable in water, even with high nanotube content.

In addition, the new nanostructured nanocomposite it has high stability against detonation compared with the polymer only, due to the nanotube interaction itself with the polymer.

This synthesis process is transferred to other polyaniline derivatives and other types of polymers conductors, such as polythiophene, polypyrrole, poly (phenylene sulfide) or its possible mixtures.

Therefore, an aspect of the present invention refers to a procedure (hereafter method of the invention) of obtaining a composition of Carbon and polymer nanotubes, comprising:

to.

sonication of a dispersion of carbon nanotubes in an acid solvent;

b.

addition of monomers in the dispersion of step (a);

C.

quick addition of an initiator radicals to the dispersion of step (b), keeping the mixture obtained at a temperature between 0 ° C and 40 ° C, preferably between 15 and 25 ° C, for a time, which can be between 30 min and 24 hours.

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Stirring by irradiation of Ultrasound (sonication) continues in steps (b) and (c).

"Quick addition" means the addition at once, not drop by drop, of the radical initiator.

Sonication can be carried out at a irradiation power between 5-3000 W being the preferred range of 10-100 W.

The polymer of the present invention is a electricity conductive material selected from the group that comprises polyaniline or its derivatives, polythiophene or its derivatives, polypyrrole or its derivatives, poly (phenyl sulfide) or its derivatives, or any of their mixtures. Understanding by "mixtures", in this particular case, to more than one polymer and / or a derived from any polymer. Preferably the polymer is polyaniline, and consequently its monomer is aniline, or its derivatives.

In the prior art they are usually use surfactants or to disperse carbon nanotubes in water or to produce PANI nanofibers. However the procedure of the invention is carried out in the absence of surfactant, by means of said procedure that Polyaniline nanostructures and carbon nanotubes are are well dispersed in the matrix without surfactant.

A preferred embodiment of the process of The invention also includes:

d.

filter, wash and dry the compound carbon and polymer nanotubes, preferably polyaniline, obtained in step (c).

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The acid solvent is a water soluble protic inorganic acid that is selected from the group comprising: hydrochloric acid (HCl), sulfuric acid (H 2 SO 4), nitric acid (HNO 3), phosphoric acid ( H 3 PO 4), boric acid (HBO 3), hydrofluoric acid (HF), hydrobromic acid (HBr), iodhydric acid (HI), perchloric acid (HClO 4), periodic acid (HIO_ {4}, tetrafluoroboric acid (HBF4) or any combination thereof. Preferably, the acid is
HCl

Preferably the concentration of solvent Acid is between 0.001 M to 5M.

Carbon nanotubes can be nanotubes of single layer carbon (SWNTs) or multi layer (MWNTs), produced by the electric arc discharge methods of chemical vapor deposition (CVD) - (including HiPCO), ablation laser or any combination of them. Preferably the nanotubes that are used in the process of the invention are of multiple layer

The amount of carbon nanotubes in the dispersion can be up to 60-70% by weight with with respect to the polymer, preferably to the polyaniline. In spite of its high concentration of nanotubes, the set continues dispersing without producing agglomerates.

Normally, in the state of the art describe compositions of this type with percentages of nanotubes below 5% with respect to the polymer, because from higher concentrations immediately agglomerate and does not disperse Good in the womb.

Preferably the amount of nanotubes of carbon is between 0.001% and 60% by weight with respect to the monomer initial, preferably to the initial aniline.

The aniline used in the process of the invention can be substituted or unsubstituted aniline, with a concentration range that can be between 0.001 g / ml and 0.2 g / ml with respect to the dispersion of the passage
(to).

The radical initiators are salts inorganic water soluble oxidants, where the oxidant is selects from the group comprising ammonium peroxodisulfate ((NH 4) 2 S 2 O 8, 2 eq.redox (number of redox equivalents per mole of oxidant)), potassium peroxodisulfate (K 2 S 2 O 8, 2 eq.redox), iron trichloride (FeCl 3, 1 eq.redox), cobalt trichloride (CoCl 3, 1 eq.redox), hydrogen peroxide (H2O2, 2 eq.redox), sulfate copper (CuSO4, 2 eq.redox), copper chloride (CuCl2, 2 eq.redox), potassium permanganate (KMnO4, 3 eq.redox), chlorate potassium (KClO3, 6 eq.redox), sodium chlorate (NaClO3, 6 eq.redox), potassium dichromate (K2 Cr2 O7, 6 eq.redox), ammonium dichromate ((NH 4) 2 Cr 2 O 7, 6 eq.redox), sodium periodate (NH4 IO4, 8 eq.redox), ammonium periodate (NaIO4, 8 eq.redox) or any of its combinations Preferably the oxidants are peroxodisulfate ammonium, iron trichloride, copper sulfate or ammonium periodate, and more preferably ammonium peroxodisulfate.

The concentration of initiators can be between 0.001 g / ml and 0.2 g / ml with respect to the total dispersion. In this dispersion the number of redox equivalents of oxidant, per mole of monomer, can be between 0.05 and 4 redox equivalents per mol.

A second aspect of the present invention is refers to a composition obtainable by the procedure of the invention (from now on composition of the invention).

The composition of the invention is much more dispersible than the nanotubes themselves, preferably
MWNTs, whereby the polymer, and more particularly PANI, acts here as an efficient vector for the dispersion of MWNTs. This makes the composition of the invention a good material for the improvement of the processing of carbon nanotubes, with the advantage of preserving the properties and functionality of polymers
drivers.

In these polyaniline-carbon nanotubes nanocompositions obtained by the process of the invention, the polyaniline is in the form of emeraldine salt (its conductive form) and in turn has nanostructured morphology
turada.

A third aspect of the present invention is refers to an aqueous dispersion comprising the composition of the invention.

In this invention, the synthesis of a PANI composite with CNTs, in which the polyaniline preserves a morphology on a nanometric scale, and that It is also dispersible in aqueous solutions. This allows improvements in the processing of said composite that can be used  in various applications in fields such as textiles, inks and functional additives, electronics with plastics, biomaterials, etc.

In a more generic way, it is shown that the procedure of the invention results in an efficient way of obtain stable water dispersions of the nanotubes themselves from carbon, which already constitutes a breakthrough in the processing and purification of said material.

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For many applications, it is highly desirable. have compositions of a conductive polymer and CNT, preferably PANI / CNT, water soluble, homogeneous and stable. And how As a result of this dispersibility in water, there are:

- New opportunities to process nanocomposite polymer-nanotubes in films, fibers, or as an additive in various matrices such as polymers, paints, inks, and printing processes for electronic circuits / devices, impregnation processes textiles, bioapplications, among others.

- New opportunities for the use of nanotubes carbon in aqueous systems such as paints, inks, printing processes, electronic circuits / devices and bioapplications

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Thus, a fourth aspect of the present invention refers to the use of the composition of the invention or of the dispersion of the invention, in paints, inks and dyes, printing processes, circuits or electronic devices or in bioapplications

In this way, the composition of the invention can be easily used to prepare functional additives for paints, inks and dyes, to prepare films and special use fibers in plastic electronics devices and optoelectronics, to prepare anticorrosive coatings.

Throughout the description and the claims the word "comprises" and its variants not they intend to exclude other technical characteristics, additives, components or steps. For those skilled in the art, other objects, advantages and features of the invention will be partly detached of the description and in part of the practice of the invention. The following examples and drawings are provided by way of illustration, and are not intended to be limiting of the present invention.

Brief description of the figures

Fig. 1.- They show the images by microscopy Scanning electronics (SEM) of powdered composites of: Fig. 1A and Fig. 1B: PANI; Fig. 1C and Fig. 1D: PANI / 5M; Fig. 1E and Fig. 1F: PANI / 10M; Fig. 1G and Fig. 1H: PANI / 30M; Fig. 11 and Fig. 1J: PANI / 50M.

Fig. 2.- They show the images by microscopy Transmission electronics (TEM) of powdered composites of: Fig. 2A: PANI; Fig. 2B: PANI / 5M; Fig. 2C: PANI / 10M; Fig. 2D: PANI / 30M.

Fig. 3.- They show the data obtained by Infrared spectrometry of powder composites of: Fig. 3A: PANI; Fig. 3B: PANI / 10M; Fig. 3C: PANI / 30M; Fig. 3D: PANI / 50M.

Fig. 4.- They show the data obtained by Raman spectrometry of the powder composites of: Fig. 4A: PANI; Fig. 4B: MWNT; Fig. 4C: PANI / 50M; Fig. 4D: The three previous.

Fig. 5.- They show the data obtained by visible ultraviolet absorption spectrometry of composites dispersed in water and HCl 0.001 M of: Fig. 5A: PANI; Fig. 5B: PANI / 5M; Fig. 5C: PANI / 30M.

Examples

The invention will be illustrated below through tests carried out by the inventors, which puts manifest the specificity and effectiveness of the procedure of the invention and the composition that is obtained by said process.

Example 1

Multi-layer carbon nanotubes (MWNTs) were prepared by the arc discharge method electric. Pure graphite bars were sublimed to a voltage of 25 V maintaining a current intensity of 60 A under an atmosphere of Helio of 66 kPa. The internal part of the cathodic deposit was collected and used without further purification, This material was formed almost exclusively by MWNTs with lengths of several microns and diameters between 20 and 50 nm.

15 mg of MWNTs were dispersed by sonication in 20 ml of 1M aqueous HCl solution for 10 minutes. Be added 0.3 ml of distilled aniline (99.5%, Scharlau Chemie, Spain) and were dispersed by sonication for another 10 minutes at 15 ° C. 20 ml of a solution of rapidly added 0.32 g of ammonium peroxodisulfate (APS, 98%, Sigma-Aldrich) in 1 M HCl. The reaction mixture at thereafter it was kept under sonication of ultrasound of 50 W of power, at a temperature within the range of 15 to 20 ° C for 2 hours.

After that time the mixture was filtered and the dark green precipitate was repeatedly washed with 1M HCl and acetone. Finally the product was dried under vacuum at room temperature for 24 hours.

The material obtained can be easily dispersed in varying amounts of water by a short sonication period (around 3 minutes). The stability of these dispersions depend on the proportion of MWNTs in the material compound.

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Example 2

90 mg of multi-layer carbon nanotubes (MWNTs) produced according to the method detailed in Example 1 were dispersed in 10 ml of 0.5 M aqueous HCl solution together with 0.3 ml of aniline for 20 minutes at room temperature. The temperature of this dispersion was adjusted to 15 ° C by a bath of thermostated ultrasound. 10 ml of a 0.5 g solution of FeCl 3 hexahydrate in 0.5 M HCl. reaction was maintained at constant temperature within the range 15 to 25ºC and under sonication of 60 W of power during 1 hour.

After that time the mixture was filtered and the dark green precipitate was repeatedly washed with 0.5 M HCl until the oxidant remains are completely removed and later with acetone. Finally the product was dried in vacuum at room temperature for 24 hours.

The material obtained was easily dispersed in varying amounts of water for a short period (around at 3 minutes) of sonication. The stability of these dispersions depends on the proportion of MWNTs in the material compound.

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Example 3

The elemental analyzes of the products were performed on a Thermo Flash EA 1112 analyzer and analyzes thermogravimetrics were performed on a Setaram thermobalance TG-DTA 92, burning 10 mg samples under a flow of air of 50 ml per minute with a heating ramp of 3ºC per minute. Table 1 shows the results of the analyzes elementary of C, H, N and O, weight loss corresponding to nanotubes obtained by TGA and polymerization performance with respect to aniline.

Sample nomenclature refers to to the proportion by weight of MWNTs with respect to the amount of aniline initially used in polymerization, so PANI does not contain nanotubes, PANI / 5M contains 5% of nanotubes, PANI / 10M 10%, PANI / 30M 30% and PANI / 50M 50%.

TABLE 1

one

The presence of nanotubes in the polymerization it seems to affect its performance, as can be observed in Table 1. The increase in the amount of MWNTs induces a slight increase in the amount of PANI obtained. It is remarkable that the same method that leads to the formation of PANI nanofibers produces homogeneous composites with a high content in MWNTs (up to 62%)

The thermogravimetries carried out with these materials showed the typical decomposition pattern associated with polyaniline doped with HCl, with a loss of water up to 100 ° C and a decomposition of polyaniline chains between 280 and 620 ° C. The composite materials showed oxidation of the MWNTs that happened at lower temperatures than in the case of samples of pure MWNTs, as shown in Table 1. This phenomenon indicates the interaction between the PANI and the MWNTs, showing the good dispersion of the latter in the matrix polymeric

Powder samples of the products were observed by scanning electron microscopy (SEM) using a Hitachi S3400N microscope and by electron microscopy of Transmission (TEM) with a JEOL JSM-6400. The Raman spectrometry was performed on a Horiba brand equipment Jovin-Yvon Infrared spectrometry is carried out incorporating the powder in KBr tablets.

SEM images (Fig. 1) clearly illustrate the nanometric morphology of these compositions. The MWNTs are they presented in a wide range of diameters and lengths, although in all cases they kept the structure straight and without defects typical of nanotubes produced by electric arc discharge. In the case of polyaniline, small particles were observed elongated about 100 nm in diameter, as can be seen in the Fig. 1A and 1B and in Fig. 2A corresponding to an image of TEM. This morphology corresponds to the nanofibrillar PANI, which It has been synthesized and characterized repeatedly, although nanofibers shown here show a much less elongated appearance and greater homogeneity in particle sizes is refer.

The nanometric size certainly favors the dispersibility of these materials. The composites present a new type of nanostructure that coexists with the nanofibers of PANI, in which the MWNTs are partially coated by PANI forming cylindrical structures of about 300 nm in diameter  (Fig. 1C). As can be seen in the TEM images (Fig. 2B, 2C and 2D), these cylinders usually house more than a single nanotube, oriented in parallel. These images allow you to appreciate the homogeneity of composite materials, which are capable of form stable dispersions for contents up to 50% in CNT The presence of these nanostructures explains the role of vector for the dispersion of CNTs exerted by polyaniline in composites, when the nanotubes are hardly dispersible coated by a layer of hydrophilic polyaniline.

The infrared spectrum obtained from Solid samples of nanostructured PANI composites are corresponds well with the own spectrum of PANI in the state of Emeraldine salt, as seen in Figures 3A-3D. Here the nanotubes do not produce any change in intensities or frequencies of infrared absorptions, since the MWNTs per themselves do not present any characteristic absorption in that zone. The spectra have the characteristic "Fano" effect of doped polyanilines.

Raman spectra for MWNTs show the typical bands for well-graffiti arc MWNTs, as seen in Fig. 4B. The relative intensity of the G band located at 1582 cm -1 in relation to the D band located at 1353 cm -1  It has a value of 7.88, which indicates the high graphitization of the nanotubes produced. For the nanostructured PANI the spectrum Raman is typical of polymethyline in emeraldine salt state, with the most intense absorptions at 1168, 1488 and 1583 cm -1, this last absorption coincides with that of greater intensity in the case of the MWNTs. This makes the presence of MWNTs in composites can only be detected in materials with a higher proportion of MWNTs, as seen in Fig. 4C, the presence of nanotubes is it is clear by the appearance of the band around 2700 cm -1 and an increase in the relative intensity of the peak around 1580 cm -1.

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Example 4

Aqueous dispersions of materials are they achieved by simple sonication of the products obtained in powder in water or aqueous solutions of 1 mM HCl for 5 min. These dispersions were analyzed by absorption spectrometry UV-Vis. The stability of these dispersions is evaluated leaving them at rest, taking aliquots from the top of the dispersions from time to time and analyzing them by UV-Vis absorption spectrometry and analysis elementary.

The stability of aqueous dispersions of Nanostructured PANI and its composites with MWNTs is remarkably high. A few minutes of sonication were enough to achieve homogeneous dispersions with sufficient stability as to be processed and characterized by spectrometry of UV-Vis absorption. The absorption spectra both of PANI as of the composites agree with the spectra found in literature of nanoparticle dispersions of PANI, as can be seen in Figures 5A, 5B and 5C. In the dispersions made in distilled water a phenomenon of detonation of polyaniline, so to get the spectrum  of PANI in its protonated state, the dispersions must be made in acidic medium. In this case a concentration of HCl 1 mM was sufficient, these dispersions being stable for days and even weeks.

The detonation effect of PANI and its composites depend on the concentration of the sample, so the low concentration dispersions are quickly transformed into Emeraldine base. The spectra obtained from these dispersions of Emeraldine base does not differ much from those of the solutions of pure base emeraldine, with absorption maxima located at 351 and 696 nm. The widest aspect of the absorption bands in the spectra of the composites is indicative of the lower homogeneity of these dispersions In fact the stability of aqueous dispersions emeraldine base is noticeably lower than the dispersions in the form of emeraldine salt. The MWNTs present in composites affect the kinetics of the reaction of detonation, this being slower for higher proportions of nanotubes in the dispersed material. The primed materials, is that is, in the form of emeraldine base, they are soluble in NMP such and such as composite materials with MWNTs synthesized by Other methods

Claims (18)

1. Procedure for obtaining a composition of carbon and polymer nanotubes, comprising:

to.

sonication of a dispersion of carbon nanotubes in an acid solvent;

b.

addition of monomers in the dispersion of step (a); Y

C.

quick addition of an initiator radicals to the dispersion of step (b), keeping the mixture obtained at a temperature between 0ºC and 40ºC, continuing with the sonication in steps (b) and (c).

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2. Method according to claim 1, which It also includes:

d.

filter, wash and dry the composition of carbon nanotubes and the polymer obtained in the step (C).

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3. Procedure according to any of the claims 1 or 2, wherein the polymer is conductive of electricity selected from the group comprising polyaniline or its derivatives, polythiophene or its derivatives, polypyrrole or its derivatives, poly (phenyl sulfide) or its derivatives, or any of its mixtures 4. Procedure according to any of the claims 1 to 3, wherein the polymer is polyaniline (and its aniline monomer) or its derivatives. 5. Procedure according to any of the claims 1 to 4, wherein the reaction temperature in the step (c) is between 15 and 25 ° C. 6. Procedure according to any of the claims 1 to 5, wherein the acid solvent is selected from group comprising: hydrochloric acid (HCl), sulfuric acid (H 2 SO 4), nitric acid (HNO 3), phosphoric acid (H 3 PO 4), boric acid (HBO 3), hydrofluoric acid (HF), hydrobromic acid (HBr), iodhydric acid (HI), acid perchloric (HClO 4), periodic acid (HIO 4), acid tetrafluoroboric acid (HBF4) or any combination thereof. 7. Procedure according to any of the claims 1 to 6, wherein the concentration of acid solvent It is between 0.001 M to 5M. 8. Procedure according to any of the claims 1 to 7, wherein the carbon nanotubes are select from single layer carbon nanotubes (SWNTs) or multi-layer (MWNTs). 9. Procedure according to any of the claims 1 to 8, wherein the carbon nanotubes are layer multiple. 10. Procedure according to any of the claims 1 to 9, wherein the carbon nanotubes are produced by the electric arc discharge methods of chemical vapor deposition (CVD) - (including HiPCO), ablation laser or any combination of them. 11. Procedure according to any of the claims 1 to 10, wherein the amount of carbon nanotubes It is up to 70% by weight with respect to the initial aniline. 12. Procedure according to any of the claims 1 to 11, wherein the amount of carbon nanotubes It is between 0.001% and 60% by weight with respect to aniline initial. 13. Method according to claim 4, where polyaniline is in the form of emeraldine salt and nanostructured 14. Procedure according to any of the claims 1 to 13, wherein the radical initiator is a oxidant selected from the group comprising peroxodisulfate ammonium ((NH 4) 2 S 2 O 8), peroxodisulfate potassium (K 2 S 2 O 8), iron trichloride (FeCl 3), cobalt trichloride (CoCl 3), hydrogen peroxide (H 2 O 2), copper sulfate (CuSO 4), copper chloride (CuCl2), potassium permanganate (KMnO4), potassium chlorate (KClO3), sodium chlorate (NaClO3), potassium dichromate (K 2 Cr 2 O 7), ammonium dichromate ((NH 4) 2 Cr 2 O 7), sodium periodate (NH 4 IO 4), ammonium periodate (NaIO 4) or any of your combinations 15. Procedure according to any of the claims 1 to 14, wherein the concentration of initiators is between 0.001 g / ml and 0.2 g / ml with respect to the total dispersion. 16. Composition obtainable by the procedure according to any of claims 1 to 15. 17. Aqueous dispersion comprising the composition according to claim 16. 18. Use of the composition according to claim 16 or of the dispersion according to claim 17, in paints, inks, printing processes, circuits or devices electronic or in bioapplications.