Dispersion of carbon nanotubes

FIELD: chemistry.

SUBSTANCE: invention can be used in manufacturing composites, containing organic polymers. A dispersion of carbon nanotubes contains 1 wt.p. of oxidised carbon nanotubes and 0.25-10 wt.p. of a product of interaction of organic amine, which contains in a molecule at least one hydroxyl group and at least one amino group, with tetraalkyltitanate.

EFFECT: dispersion is stable with the high content of nanotubes and minimal content of ballast substances.

8 ex

 

The invention relates to the technology of carbon nanomaterials, particularly to methods of obtaining compositions containing carbon nanotubes dispersed in different environments.

Carbon nanotubes (CNTS) tend to form agglomerates, which complicates their implementation in different environments. Typically, to achieve a uniform distribution of carbon nanotubes in solvents and polymers used surfactants, sonication or treatment with various mechanical mills, and the original CNTS functionalitywith by chemical grafting of certain groups. In order for the carbon nanotubes can be entered in various organic and inorganic environment (water, various solvents, polymers), without significantly changing the existing process line, it would be desirable to create a prepared concentrated dispersions of carbon nanotubes, which could be introduced in the organic system by simple mixing without the use of ultrasound or other methods that require the use of complex equipment. However, known up to the present time dispersion of carbon nanotubes stabilized by one method or another, usually stable only at very low concentration of CNTS, usually not more than 0,01-0,1%. The use of such razbavlennyi impractical because simultaneously with the nanotubes in the target system to be paid a large amount of auxiliary substances, which, when included in the composition, reduce the strength properties of the material, which necessitates their removal, for example, by distillation in vacuum, annealing, and the resulting complexity of the process.

Known dispersion of CNTS in water containing carbon nanotubes and one or another surfactant (anionic, cationic or nonionic) as a substance that stabilizes the dispersion (1. Chen, L., Xie, H., Li Y., Yu W. Applications of cationic gemini surfactant in preparing multi-walled carbon nanotube contained nanofluids // Colloids and Surfaces A: Physicochem. Eng. Aspects 330 (2008) 176-179. 2. Rastogi R., Kaushal R., Tripathi S.K., Sharma A.L., Kaur I., L.M. Bharadwaj Comparative study of carbon nanotube dispersion using surfactants //Journal of Colloid and Interface Science 328 (2008) 421-428. 3. Vaisman L., H.D. Wagner, Marom G. The role of surfactants in dispersion of carbon nanotubes //Advances in Colloid and Interface Science 128-130 (2006) 37-46. 4. The application of the U.S. 20060099135. Carbon nanotubes: high dispersion of solids and their nematic gels, IPC D01F 9/12, 2006).

Common essential characteristics of dispersions of carbon nanotubes in this group and the claimed invention is the content in their composition of carbon nanotubes and a stabilizing substance.

The disadvantage of these dispersions is that, typically, surfactants are not working in organic solvents, which does not allow to obtain a stable dispersion of CNTS in organic RA is the founders. In addition, these dispersions, due to the presence of surface-active substances (surfactants)may not be directly included in the composite materials, because of surfactants in this case represent a ballast substances, which often worsen the properties of the composite material. In addition, with the introduction of aqueous dispersions of carbon nanotubes stabilized by surfactants in organic systems, as a rule, is the coagulation of carbon nanotubes because of the known surfactants may not be equally effective in water and in organic medium.

Known dispersion of CNTS in water and in polar organic solvents containing carbon nanotubes, the surface of which contains grafted oxide groups (hydroxyl, carboxyl, quinoid) (5. Datsyuk V., M. Kalyva, K. Papagelis, J. Parthenios, D. Tasis, Siokou A., I. Kallitsis, Galiotis C. Chemical oxidation of multiwalled carbon nanotubes // Carbon, 2008, vol. 46, p.833-840. 6. Schierz, A., Zanker H. Aqueous suspensions of carbon nanotubes: Surface oxidation, colloidal stability and uranium sorption //Environmental Pollution, 2009, vol. 157, p.1088-1094. 7. Shieh Y.-T., Liu, G.-L., Wu, H.-H., Lee C.-C. Effects of polarity and pH on the solubility of acid-treated carbon nanotubes in different media // Carbon, 2007, vol.45, p.1880-1890). The introduction of surface oxide groups is carried out by treating the CNTS of different oxidants in liquid or gas phase in liquid phase nitric acid, a mixture of nitric and sulphuric acids, a mixture of hydrogen peroxide with sulfuric acid, ammonium persulfate it is moral or ammonia environment, potassium permanganate in acidic medium in the gas phase - pairs of nitric acid, nitrogen dioxide, ozone, oxygen). Due to the presence of polar oxide groups of the oxidized CNTS better wetted with water and polar organic solvents, making the dispersion thus treated CNTS in water or polar organic solvents stable even in the absence of surfactant. Typically, these dispersions are sufficiently stable in alkaline and mildly alkaline environment and unstable in neutral and acidic medium, because in the alkaline environment of the surface carboxyl groups dissociate, resulting in the carbon nanotubes appears negative charge, preventing their coagulation.

Common essential features known dispersions of this group and claimed is the presence of a dispersion of carbon nanotubes with oxidized surface.

A disadvantage of the known dispersions are considered group is a very small concentration of CNTS, usually not more than 0,01-0,1%, above which the dispersion becomes unstable. This forces when creating composite materials to enter, and then remove a large amount of ballast solvent.

Known dispersion of CNTS in water and organic solvents, stable block copolymers (8. Sluzarenko N., Heurtefeu Century, M. Maugey, C. Zakri, Poulin P., S. Lecommandoux Diblock copolyme stabilization of multi-wall carbon nanotubes in organic solvents and their use in composites // Carbon 44 (2006) 3207-3212. 9. Wang Z., Liu Q., Zhu, H., Liu H., Chen Y., Yang M. Dispersing multi-walled carbon nanotubes with water-soluble block copolymers and their use as supports for metal nanoparticles // Carbon 45 (2007) 285-292. 10. The application of the U.S. 20090118420. Dispersion of carbon nanotubes in block copolymers and functional composite materials and coatings, IPC C08L 25/08, B29D 7/01, 2009), synthetic polymers (11. Darsono N., Yoon, D.-H., Kim J. Milling and dispersion of multi-walled carbon nanotubes in texanol // Applied Surface Science 254 (2008) 3412-3419. 12. Ogoshi T., Saito T., Yamagishi T., Nakamoto Y. Solubilization of single-walled carbon nanotubes by entanglements between them and hyperbranched phenolic polymer //Carbon 47 (2009) 117-123. 13. U.S. patent 7,682,590. Dispersion of carbon nanotubes dispersed in the polar organic solvent, and a method thereof IPC D01F 9/12; VV 1/00; C08J 3/02; SC 3/04; SC 7/24; C08L 39/06, C09D 139/06, 2010. 14. Lee J.U., Huh j, Kim K.H., Park, C., W.H. Jo Aqueous suspension of carbon nanotubes via non-covalent functionalization with oligothiophene-terminated poly(ethylene glycol) // Carbon 45 (2007) 1051-1057, polymeric and low molecular weight substances of biological origin (15. Li Z., Wu Z., Li K. The high dispersion of DNA-multiwalled carbon nanotubes and their properties // Analytical Biochemistry 387 (2009) 267-270. 16. U.S. patent 7,588,941 Dispersion of carbon nanotubes on nucleic acids, IPC C12Q 1/68; SN 21/04; SM 1/00; C12N 11/16, 2009. 17. The application of the U.S. 20090162277. Dissolution of single-wall carbon nanotubes in lysophospholipid, IPC AC 9/14, C12Q 1/02, AK 51/02, AK 49/00, 2009. 18. Moulton SE, Minett, A.I., R. Murphy, K.P. Ryan, D. McCarthy, J.N. Coleman, W.J. Blau, Wallace G.G. Biomolecules as selective dispersants for carbon nanotubes // Carbon 43 (2005) 1879-1884. The surface of the CNTS can be either an oxide is military, and unoxidized.

Common essential features of these dispersions and the claimed invention is the presence of a dispersion of carbon nanotubes auxiliary substances, stabilizing the variance.

A disadvantage of the known dispersions of this group is the presence in their composition of ballast substances, which, when using a dispersion of carbon nanotubes to obtain a polymer (e.g. epoxy) composite materials are not always compatible with the polymer matrix composite material and degrade its properties.

Closest to the claimed invention is a dispersion of the oxidized carbon nanotubes, including organic amine containing in the molecule at least one hydroxyl group and at least one amino group, bonded to aliphatic carbon atoms, such as triethanolamine, and the solvent (KR application No. 2012021807, IPC SW 31/02, 2012).

The disadvantages of these dispersions are high cost, which inevitably caused a very complex, difficult scalable technique to obtain with the use of aggressive reagents (processing of carbon nanotubes large quantities of acid, then with thionyl chloride, then amines). If you conduct a direct reaction carboxylating nanotubes with amines, it takes a long time (3-10 days at 70-140°C) and skin is of a large excess of amine, which is then to be washed. The presence of all these numerous operations leads to the fact that the resulting dispersion is very expensive. In addition, the chemical grafting of amines to the surface of the nanotubes amino groups into amide groups, which, if these dispersions to be used as hardeners for epoxy resins require a much higher temperature curing. In addition, unknown compatibility thus obtained dispersion with epoxy resins.

The basis of the claimed invention is the task by selecting the structure of organic amines, to create a stable dispersion of carbon nanotubes in the absence or minimum permissible content of ballast substances, which need to be removed with the introduction of dispersion in polymer compositions, in particular epoxy, and which could be used as nano-modifier hardener or accelerator curing epoxy compositions.

The problem is solved in that the dispersion of carbon nanotubes containing oxidized carbon nanotubes and a solvent, contains the product of the interaction of organic amine containing in the molecule at least one hydroxyl group and at least one amino group, with tetraalkylammonium in the following ratio of components:

oxide the main carbon nanotubes - 1 mass

the product of the interaction of the specified organic amine with

tetraalkylammonium - 0.25 to 10 mass

Optionally, the dispersion may also contain a solvent, the amount of which to take the necessary working viscosity of the dispersion. The solvent may be used organic solvents that are compatible with the components of the dispersion, and the introduction of dispersion in the composition of composite materials with the components of composite material. As solvents can, for example, used glycerin, monobutyl ether of diethylene glycol and other esters of ethylene glycol and diethylene glycol, N-organic, and others.

As one of the possible embodiments of the invention, as the organic amine used triethanolamine.

As one of the possible embodiments of the invention, as the organic amine used Tris-2,4,6-(N,N-dimethylaminomethyl)phenol.

As products of interaction of tetraallylsilane with organic amine can be used in a variety of products, known in the art. For example, in the reaction of tetrabutyltin with triethanolamine (from 1 to 2 mol of triethanolamine per 1 mole of titanate) are formed of different products, the composition of which is known (22. Kirk-Othmer Encyclopedia of Chemical Technology (4th Edition), vol.24, 538, p. P.141, 142). These products are industrial is the laziness and apply for example, as curing agents of epoxy resins and for other purposes (23. Himeks limited, http://www.chimexltd.com - catalogue of the hardeners of epoxy resins, 24. http://www.vitareaktiv.ru/catalogue/ trietanolamintitanat, 25.http://capatue.en.made-in-hina.com/product/e MOSS opjvLKWA/China-Triethanolamme-Titanium-Complex-Tyzor-TE-CAS-No-36673-16-2-.html). As a rule, technical products are a mixture of compounds of different structure, but this does not prevent their use for the implementation of the claimed invention.

The following are the data demonstrating the ability of the proposed method and its effectiveness.

For carrying out the invention was applied following the initial substance.

Carbon nanotubes tunic with conical orientation of the carbon layers produced by Nanocenter was characterized by an outer diameter of 20-70 nm and a length of more than 2 μm.

Carbon nanotubes Taunit-M with cylindrical orientation of the carbon layers produced by Nanocenter was characterized by an external diameter of 8 to 15 nm and a length of more than 2 μm.

For oxidation of carbon nanotubes taunt and Taunit-M and vaccinations to their surface carboxyl and hydroxyl groups of the nanotubes were treated with a solution of ammonium persulfate with the addition of ammonia, washed with water and dried.

Triethanolamine was used technical on THE 2423-168-00203335-2007.

Tris-2,4,6-(N,N-dimethylaminomethyl)phenol was used stamps shall lcopen MA (hardener epoxy resins).

Tetrabutyltin applied technical on THE 6-09-2738-89.

To control the dispersion of the carbon nanotubes and the stability of the dispersions during storage was measured optical density of the dispersion, diluted with water, using a photometer, ck-3, at a wavelength of 500 nm. From the obtained data was calculated absorption coefficient K=D/(C*L), where D is the optical density (dimensionless), C is the concentration of carbon nanotubes in the measured solution in g/l, L is the length of the cuvette (cm). Control experiments it was found that the optical density in the investigated systems is proportional to the concentration of the nanotubes, i.e. we observe the law of Lambert-Baer, and allows you to use the value of the coefficient of light absorption as a parameter characterizing the dispersion. If there is a large dispersion of agglomerates of nanotubes, the size of which is comparable to or greater than the wavelength of light (500 nm), the value of K decreases. As reference points, you can take the value 10=34,1 l/g·cm, which was measured for the oxidized CNTS Taunit dispersed using ultrasound in dimethylacetamide. It has been found that in this system nanotubes do not form agglomerates. In addition, to visually assess aglomerirovannosti dispersions of carbon nanotubes (diluted with solvent) used this criterion as the transparency of the solution and the absence of mutipoint experiments have shown, in all cases, the dispersion of CNTS in solvents that do not contain large agglomerates are transparent and do not show turbidity. Agglomerated same dispersion always visually are muddy.

Example 1. This example used the product of the interaction of triethanolamine (tea) with tetrabutylammonium (TBT). Getting this product had known in the art method, namely the exchange reaction tetrabutyltin and triethanolamine at a molar ratio of tea:TBT=2:1. To this mixture components was heated in a flask equipped with a nozzle for distillation of volatile substances in a stream of argon at 120°C. to remove n-butanol, which is formed in the exchange reaction of tea with TBT. Received the product of the interaction (tea-TBT) as a vitreous mass, which is softened when heated to 60-80°C. In a porcelain mortar made of 1 g of oxidized carbon nanotubes brand "Taunit", 2 g obtained by tea-TBT and 10 ml of solvent (water). After grinding for 15 min obtained a homogeneous black dispersion not containing agglomerates, which upon dilution with water gave a clear solution. As the original dispersion and its solutions when diluted in water were stable when stored.

Example 2. Carried out analogously to example 1, but the number of tea-TBT took 0.25 was Obtained a stable dispersion.

Example 3. Khujand who have been analogously to example 1, but the number of tea-TBT took 10, Got a stable dispersion.

Example 4. Carried out analogously to example 1, but the number of tea-TBT took 0,15, In this case a stable dispersion could not be obtained.

Experiments have also shown that the increase in the number of tea-TBT more than 10 g per 1 g of nanotubes is impractical for economic reasons.

Example 5. Carried out analogously to example 1, but as the organic amine used Tris-2,4,6-(N,N-dimethylaminomethyl)phenol in the same molar ratio with tetrabutylammonium. In this case, the product of the interaction of the amine with TBT was a solid mass of brown color. In a porcelain mortar made of 1 g of oxidized carbon nanotubes brand "Taunit", 3 g of the obtained titanium containing product and 10 ml of solvent (water). After grinding for 20 min obtained a homogeneous black dispersion not containing agglomerates. The resulting dispersion was stable when stored.

Example 6. In this example, as carbon nanotubes applied oxidized nanotubes tounit)

In a mortar were placed 1 g of oxidized nanotubes Taunit-M, 4 g of triethanolamine and 20 g of N-methylpyrrolidone. In this case, the addition of solvent was necessary, because without solvent system was so thick that process it was not possible. See the camping was ground in a mortar for 1 hour. Received a viscous black liquid, which was dissolved in N-organic no sediment.

Example 7. This example used a reaction product of triethanolamine (tea) with tetrabutylammonium (TBT) in a molar ratio of 2:1. This product was synthesized by heating a mixture of tea with TBT in the ratio indicated in the installation for the distillation in a stream of argon. The process was carried out at a slow temperature rise of the mixture to 120°C., the control of flowing the reaction was performed according to the mass Athanasios n-butanol (volatile reaction product). It was found that under these conditions, the reaction of tea with TBT leads to removal from molecules TBT all four butoxyl groups (due to the transesterification of the hydroxyl groups triethanolamine). The resulting product was a viscous liquid, and when cooled to room temperature glassy amorphous mass, such as rosin. The product was soluble in water and resistant to hydrolysis. It should be noted that sales of the product obtained by the reaction of 2 mol of tea with 1 mol TBT when Stripping 2 butoxyl groups, in aqueous solution is unstable. Thus, hydrolytic stability depends on the degree of interesterification butoxyl groups TBT hydroxyl groups of the IEA.

For convenience, we synthesized product, glassy at room temperature, was what assault solvent monobutyl ether of diethylene glycol (MEG) in an amount of 1 mol of BAG 1 atom of titanium. After mixing with the solvent obtained viscous liquid.

In a mortar were placed 2 g of oxidized CNTS Taunit, 8 g of the above product containing BAG and rubbed within half an hour. Got a black gel, soluble in water, glycerine and epoxy resin ED-20. An aqueous solution obtained by diluting this gel was stable for at least a month. So, to check the stability of the aqueous solution of the sample 0,1667 g of gel was dissolved in 30 ml of water and diluted in a liter volumetric flask to volume of 1 liter was Measured optical density of this solution at the wavelength of 500 nm. From the obtained data was calculated absorption coefficient (K). It was found that the value of K was reached 28.5 l/g·cm to a freshly prepared solution and 27.6 l/g·cm after storage for one month. Sediment or turbidity during storage diluted with water dispersion during the month was not observed.

Example 8. In this example, used a complex compound of an organic amine of Alkoven MA tetrabutylamonium in a molar ratio of 2:1. In this case, to obtain the complex compounds just mixed components. The transesterification not conducted.

In a mortar were placed 1 g of oxidized CNTS Taunit and specified complex the second connection Alkoven MA TBT in the amount of 4 g in terms of Alkoven MA. After grinding for half an hour got the gel, soluble in epoxy. In water, this gel gave a residue, because the specified compound is unstable to hydrolysis.

Due to the solubility of the inventive dispersions of carbon nanotubes in epoxy resins, these dispersions can be used as nanomodification hardeners of epoxy resins.

Thus, the claimed invention can be used to obtain stable dispersions of carbon nanotubes in various organic solvents, as well as for the introduction of carbon nanotubes in organic polymers.

Dispersion of carbon nanotubes containing oxidized carbon nanotubes and a solvent, characterized in that it contains the product of the interaction of organic amine containing in the molecule at least one hydroxyl group and at least one amino group, with tetraalkylammonium in the following ratio of components:
oxidized carbon nanotubes - 1 parts by weight of
the product of the interaction of the specified organic amine with tetraalkylammonium - 0.25 to 10 parts by weight of



 

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EFFECT: higher efficiency of production at high magnetic permeability.

FIELD: metallurgy.

SUBSTANCE: method of iron powder production involves preparation of iron-carbon melt with the carbon content of 3.9-4.3 wt %, its spraying into water by compressed air, dehydrating, drying to produce raw powder with the proportion of concentration of oxygen to carbon being equal to 1.1-2.0, and grinding down to the particle size of maximum 0.250 mm. The ground raw powder is mixed with granulated iron oxides produced from waste rolling muriatic pickling solutions, with the concentration of impurities of maximum 2 wt % and granule size of maximum 0.160 mm. Concentration of granulated iron oxides in the mix with iron powder is determined, then the obtained mix is annealed in a furnace under the temperature of 950-1000°C for 1.5-2 hours in the layer of 25-35 mm high on a continuously moving band, crushing with the isolation of proper fraction of iron powder with the particle size of less than 0.200 mm.

EFFECT: production of high quality iron powder with high chemical purity, satisfactory fluidity, high compressibility and increased strength of pressing.

2 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a matrix carrier composition for use in a pharmaceutical delivery system for oral administration, which is a suspension consisting of particles of a material in a continuous oil phase. The material consisting of particles comprises a first solid phase comprising silicon dioxide nanoparticles having hydrophobic surface, with particle size of 5-1000 nm, and a second solid phase comprising a biopolymer having hydrophilic and hydrophobic parts, said biopolymer containing polysaccharide. Said continuous oil phase is associated with the first and second solid phases, and the weight of the biopolymer is double that of the silicon dioxide nanoparticles. The invention also relates to a method of producing a matrix carrier composition, which includes mixing a first solid phase comprising silicon dioxide nanoparticles with oil, activating a second solid phase containing polysaccharide, wherein activation includes grinding, vacuum treatment, chemical treatment or ultrasonic treatment, adding said activated second solid phase to the oil and mixing the oil containing the first solid phase and oil containing the activated second solid phase.

EFFECT: improved efficiency and bioavailability of a medicinal agent encapsulated in a matrix carrier.

13 cl, 3 dwg, 1 tbl, 8 ex

FIELD: metallurgy.

SUBSTANCE: proposed method comprises making the mix of titanium and lithium compounds to be heat treated, heat treatment products being annealed. Beforehand, said titanium tetrachloride solution is subjected to salt hydrolysis in boiling solution of said tetrachloride at 120÷150°C. Then, formed pulp is filtered to flush obtained precipitate with solution of alkaline agent. The latter is selected from the group consisting of ammonia carbonate, ammonia hydroxide, lithium carbonate, lithium hydroxide. Now, it is flushed with water and dried. Lithium compound with titanium and lithium is selected from the group including: lithium carbonate, hydroxide, oxalate, acetate and mixes thereof. Then, heat treatment is performed at 400-500°C under pyrolysis conditions. Annealing of heat treated mix at conducted at 800-900°C for 5 hours.

EFFECT: simplified production of nanosized particles of spinel-structure powders of lithium titanate Li4Ti5O12.

5 cl, 3 dwg, 2 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to the chemical industry and can be used to produce composites which are used in photocatalytic processes as catalysts of oligomerisation of olefins and polymerisation of ethylene. The composite material based on silica gel is obtained by precipitation of silicon dioxide from sodium silicate in the presence of titanium dioxide or copper oxide by bubbling of carbon dioxide through the thickness of the suspension at the atmospheric pressure to form the composite material with the type "core (silicon dioxide)/shell (metal oxide)". The method can be used both in the laboratory and in industrial conditions.

EFFECT: invention enables to simplify the process of obtaining a composite, as the need for complex instrumental execution of the process is eliminated, connected with the use of high pressure of carbon dioxide in obtaining the silica gel, as well as environmental safety of the technology, which is connected to the lack of carbon dioxide emissions, achieved by its repeated use.

3 dwg, 2 ex

Fuel composition // 2531146

FIELD: chemistry.

SUBSTANCE: invention relates to a fuel composition, which contains hydrocarbon fuel, components, which arise at a high-voltage electric discharge, additional carbon-containing additives and a disperse phase. As the carbon-containing additives the composition includes nanoparticles in the form of carbon nanotubes, obtained by catalytic pyrolysis of acetylene on nanoclusters of iron and cobalt in an aluminium oxide matrix and having a structure of twisted balls with a diameter over 2 mcm with an average external diameter ~20-30 nm, or nanoparticles in the form of graphene, which has a layered structure with the granule size ~ 400 nm and obtained by a chemical method, consisting in oxidation of graphite layers with the following reduction and obtaining nanometer layers of a carbon product. The quantitative ratio of components, included in the composition, constitutes: hydrocarbon fuel - 100 g; carbon nanotubes or graphene - 0.5 g, remaining part - disperse phase.

EFFECT: composition makes it possible to reduce the time of delay of fuel ignition and increase stability of the flame burning.

4 cl, 3 dwg

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