RU2515858C2 - Finely-disperse organic suspension of carbon metal-containing nanostructures and method of its production - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to the field of physical and colloidal chemistry and can be used in obtaining polymer compositions. Finely-disperse organic suspension of carbon metal-containing nanostructures is obtained by interaction of nanostructures and polyethylene polyamine. First, powder of carbon metal-containing nanostructures, representing nanoparticles of 3d-metal, such as copper, or cobalt, or nickel, stabilised in carbon nanostructures, are mechanically crushed, after which, mechanically ground together with introduced in portions polyethylene polyamine until content of nanostructures not higher than 1 g/ml is reached.

EFFECT: invention ensures reduction of energy consumption due to the fact that obtained finely-disperse organic suspension of carbon metal-containing nanostructures is capable of recovery as a result of simple mixing.

2 cl, 5 dwg, 2 ex

Description

The invention relates to the field of physical and colloidal chemistry and consists in obtaining finely divided organic suspensions of nanostructures used in the modification of epoxy compositions.

Known organic suspension for the modification of epoxy resin ("Optimization of the properties of epoxy composites modified with nanoparticles" T.A. Nizina, P.A. Kislyakov, Building Materials 2009, No. 9, pp. 78-80) containing a fulleroid multilayer synthetic nanomodifier Astralen NTC dispersed in polyethylene polyamine (PEPA), which is a hardener of epoxy resins.

For the manufacture of a known suspension in PEPA in the amount of 0.0075-0.03%, a fulleroid multilayer synthetic nanomodifier astralen NTC was introduced. The mixture was dispersed by ultrasound with an intensity of 22 kW / m ² frequency of 18 kHz at a power of 40 watts. The resulting suspension remained stable for several days, after which the dispersed phase coagulated and its activity decreased.

A disadvantage of the known suspension is the low aggregative stability, limiting the use of the suspension on an industrial scale, in long production cycles.

A known suspension of carbon nanotubes, the amount of dispersed additives in which is not more than 1 g / ml, see US Pat. US No. 6783746, publ. 2004 year

A known suspension was obtained using the grinding of carbon nanotubes with a surfactant containing PEPA. During grinding, physical sorption of surfactant molecules on the surface of nanostructures occurs, which increases the stability of nanostructures.

A disadvantage of the known suspension is the low strength of the surfactant shell on the surface of active carbon nanotubes, which leads to the desorption of surfactant molecules and the release of nanostructures with their subsequent irreversible coagulation, for example, as a result of temperature changes or other effects during storage of suspensions. This eliminates the possibility of restoring a suspension of nanostructures without significant energy costs.

The closest technical solution is a finely divided organic suspension of carbon metal-containing nanostructures (patent RU No. 2436623, publ. 12/20/2011). The known suspension contains carbon nanostructures dispersed in PEPA medium, including 3d metal (copper, or cobalt, or nickel and its compounds). For the manufacture of the known suspension, carbon-containing metal nanostructures were used, prepared in the combined polymer matrix of polyvinyl alcohol and PEPA by low-temperature synthesis with the addition of aqueous solutions of copper or cobalt or nickel salts as the metal-containing phase (patent RU No. 2323276, publ. May 19, 2008 )

A method of manufacturing a suspension includes pre-washing the powder of carbon metal-containing nanostructures with a slightly alkaline solution to remove chlorine ions and drying. The dried nanostructures are mechanically ground, then added portionwise when mixed in PEPA in an amount of not more than 5 mg / ml.

A known suspension containing carbon nanostructures dispersed in PEPA medium, including 3d metal (copper, or cobalt, or nickel and its compounds), retains aggregative stability from 20 to 35 days.

Physical sorption of PEPA molecules on the surface of nanostructures, resulting from the mixing of components, does not provide a sufficiently strong interaction of PEPA molecules with nanostructures; after 20-35 days of storage, the nanostructures coagulate - they form agglomerates, sedimentation occurs. Exceeding the threshold of the content of carbon metal-containing nanostructures in suspension (5 mg / ml) leads to rapid coagulation of particles and loss of activity. The use of metal chlorides in the synthesis as a metal-containing phase involves leaching of chlorine ions, which leads to loosening of the structure and destabilization of carbon shells, which in turn reduces the activity of nanostructures. To restore the known suspensions of these nanostructures, it is necessary to destroy the formed agglomerates, which is associated with high energy consumption and is not always possible. In addition, the need for leaching of chlorine leads to additional energy costs and is unacceptable in long production cycles. Thus, the use of the suspension on an industrial scale is limited by the agglomeration of carbon metal-containing nanostructures, a low threshold for the content of the dispersed phase (not more than 5 mg / ml), and the need for preliminary washing of the nanostructures with weakly alkaline solutions.

The technical effect of the invention is to obtain a suspension capable of recovering as a result of simple mixing without the use of significant energy costs.

The recovery of a suspension of carbon metal-containing nanostructures is the destruction of the aggregates of particles of carbon metal-containing nanostructures formed during coagulation while maintaining the original particle size and uniform distribution of particles throughout the dispersion medium.

To achieve the technical effect of the invention in a method for producing a finely dispersed organic suspension of carbon metal-containing nanostructures by the interaction of nanostructures and polyethylene polyamine, the powder of carbon metal-containing nanostructures, which are 3d metal nanoparticles, such as copper, or cobalt or nickel, stabilized in carbon nanostructures, is ground mechanically, then ground in conjunction with a portion-administered polyethylene polyamine. The content of nanostructures in the mixture does not exceed 1 g / ml.

When grinding PEPA and carbon nanostructures with metal nanoparticles stabilized inside, as a result of a mechanochemical reaction, amino groups are formed on the surface of carbon metal-containing nanostructures (nanocomposites particles) (MA Chashkin. Features of metal / carbon nanocomposites modification of cold cured epoxy compositions and study of the properties of the obtained polymer compositions. // Abstract of Diss. Candidate of Technical Sciences. - Perm: PNIPU, 2012.17 p.).

Carbon metal-containing nanostructures, which are nanoparticles of a 3d metal, such as copper, or cobalt, or nickel, stabilized in carbon nanostructures, are structurally ordered due to the association of the carbon shell with 3d metal clusters. Due to the presence of free orbitals, 3d metals have a high coordination ability. The nitrogen atoms in the PEPA contain an unshared electron pair; therefore, when the components are rubbed together between carbon metal-containing nanostructures (nanocomposite particles) and PEPA molecules, a chemical interaction occurs with the formation of nitrogen-containing groups on the surface of carbon metal-containing nanostructures. In this case, the surface energy of nanostructures decreases, part of which is spent on the formation of nitrogen-containing groups on the surface of carbon metal-containing nanostructures.

The carbon film on the surface of 3d metal nanoparticles protects them from oxidation and initiates the appearance of nitrogen-containing groups on the surface of nanostructures, which increase the stability of carbon metal-containing nanostructures, preventing the irreversible coagulation of the dispersed phase.

During storage of the suspension, PEPA molecules and nanostructures containing nitrogen in the shell are associated with each other using hydrogen bonds between the nitrogen-containing groups NH, NH ₂ . Floccules are formed - “aggregates” of nanostructures interconnected via PEPA molecules via weak hydrogen bonds.

Aggregates have weaker bonds between particles within the aggregate than agglomerates (Encyclopedic Dictionary of Nanotechnology. - 2010, http://dic.academic.ru/dic.nsf/nanotechnology/355). Floccules “aggregates” are easily destroyed by mixing the contents of the suspension without the use of special devices, and the dispersed phase is evenly distributed over the volume of the dispersion medium, acquiring the original size and activity.

The ability to restore the suspension allows it to be used in long production cycles, for example, in the mass production of pressure vessels by dry winding.

At a concentration of nanostructures of more than 1 g / ml in suspension, after several days of storage, hard-to-break agglomerates are formed.

The invention is illustrated by drawings.

Figure 1. Table of optical densities of finely dispersed suspensions of carbon copper, nickel and cobalt-containing nanostructures at a nanostructure concentration of 0.1 mg / ml on the day of manufacture and after recovery.

Figure 2. Photos of the "obsolete" suspension (a) and suspension after recovery (b).

Figure 3. IR spectra of finely dispersed suspensions of carbon-containing copper (a, b), nickel-containing (c, d) and cobalt-containing (e, e) nanostructures, respectively, on the day of manufacture (a, c, e) and after recovery (b, d, e) on the day the beginning of the “aging” of the suspension - the fifth day after the manufacture of the suspension at a concentration of nanostructures of 1 g / ml

Figure 4. IR spectra of finely dispersed suspensions of carbon-containing copper (a, b), nickel-containing (c, d) and cobalt-containing (e, e) nanostructures, respectively, on the day of manufacture (a, c, e) and after reduction (b, d, e) at a concentration nanostructures 0.1 mg / ml.

Figure 5 IR spectra of a finely dispersed suspension of carbon-containing copper nanostructures with a concentration of 1 g / ml: control on the day of manufacture (a), on the fifth day after preparation before recovery (b) and after recovery (c).

Suspensions were made using known carbon metal-containing nanostructures obtained in a polyvinyl alcohol matrix by low-temperature synthesis with the addition of copper or cobalt or nickel oxides as a metal-containing phase (RF Patent No. 2337062, publ. 2008; Trineeva V.V., Maeva I.S., Denisov V.A., Kodolov V.I. Obtaining nanostructures based on metal oxide compounds and polyvinyl alcohol. // Proceedings of the International Conference. Nanotechnology for Green and Durable Construction, 2010, P.68-72; K odolov V.I., Kovyazina O.A., Trineeva V.V., Vasilchenko Yu.M., Bakhrushina M.A., Chmutin I.A. On the production of metal-carbon nanocomposites, aqueous and organic fine suspensions based on them .-- The site of OJSC Izhevsk Electromechanical Plant Kupol. - Access mode: http://www.kupol.ru/system/files/o_proizvodstve_metalluglerodnyh_nanokompozitov_vodnyh_i_organicheskih_tonkodispersnyh_suspenziy_na_ih_osnove.

Carbon metal-containing nanostructures are nanoparticles of a 3d metal, such as copper, or cobalt, or nickel, stabilized in carbon nanostructures (coated with a carbon film-shell consisting of carbon fibers associated with metal clusters). Nanostructures, depending on the synthesis temperature, can take the form of films, balls, and tubes.

To obtain a suspension, the powder of carbon metal-containing nanostructures was mechanically ground. In this case, preliminary activation of nanostructures occurs due to the destruction of most of the aggregates and agglomerates formed due to the high activity of nanostructures during storage of the powder.

Then, the powder of carbon metal-containing nanostructures together with the portion-injected PEPA was mechanically grinded until the content of nanostructures in the mixture was not more than 1 g / ml.

When the powder of carbon metal-containing nanostructures is ground together with PEPA, in addition to the most complete destruction of aggregates and agglomerates remaining after mechanical grinding, PEPA molecules interact with the formation of nitrogen-containing groups on the surface of the nanostructures. The resulting nitrogen-containing groups significantly reduce the degree of formation of agglomerates. The grinding time of nanostructures with PEPA depends on the volume of the produced finely divided organic suspension.

The size of the dispersed phase and the uniformity of its distribution over the volume of the resulting suspension was determined by measuring the optical density of the suspension using a KFK-3-01 photocolorimeter.

To determine the chemical composition of the suspensions and to determine the activity of the suspensions and their ability to recover from the intensity of deformation vibrations, an FSM 1201 FT-IR spectrometer was used.

Example 1. A powder of carbon copper, nickel, and cobalt-containing nanostructures was ground for 3 minutes in a Retsch RM 200 mechanical mortar, then ground in a mortar with portionwise introduced PEPA until the nanostructure content reached 0.1 mg / ml.

On the day of the manufacture of finely dispersed organic suspensions of carbon copper, nickel and cobalt-containing nanostructures, their optical density was measured (Fig. 1). After separation of the suspension in order to restore it, the entire volume was thoroughly mixed, a sample was taken for which the optical density was measured (Fig. 1). For clarity, the image on the lumen of the stratified suspension and suspension after mixing (restored) are shown in figure 2. The optical density of the reconstituted suspensions was close in magnitude to the optical density of the suspensions on the day of manufacture (FIG. 1). This suggests that the suspensions before and after recovery are characterized by the same size and distribution of the dispersed phase in the volume under study. This fact indicates the ability of suspensions to recover.

Example 2. The powder of carbon copper-, nickel- and cobalt-containing nanostructures was ground for 3 minutes in a Retsch RM 200 mechanical mortar, then it was ground with a portion-injected PEPA to achieve a nanostructure content of 1 g / ml.

Due to the fact that the optical density of a suspension with a concentration of 1 g / ml cannot be estimated by spectrophotometry, since a suspension with such a concentration is an opaque paste in the range of operating wavelengths of the KFK-3-01 photocolorimeter (320-940 nm), to determine the ability of suspensions to recover, the IR spectra of suspensions of carbon copper (a, b), nickel (c, d) and cobalt-containing (e, f) nanostructures with a concentration of 1 g / ml obtained in Example 2 were recorded on the day the suspension was prepared and on the day the stratification of susp nzii - fifth day after production the slurry after stirring the slurry in order to restore (Figure 3).

The position of the radiation peaks in the IR spectra determines the chemical composition of the suspensions, in turn, the intensity of the emission bands characterizes the activity of the suspensions and, indirectly, the particle size of the dispersed phase:

the higher the intensity of the bands of valence and skeletal vibrations, the higher the activity, and the particle size is less;

for bending vibrations, on the contrary, the higher the intensity of the bands, the lower the activity and the larger the particle size of the dispersed phase.

The position and intensity of the peaks in the spectra of the suspensions in figure 3 are the same, which indicates the ability of the suspension with a concentration of nanostructures of 1 g / ml to recover.

The IR spectra of finely dispersed organic suspensions of carbon copper (a, b), nickel (c, d) and cobalt-containing (e, f) nanostructures with a concentration of 0.1 g / ml obtained in Example 1 are shown in Fig. 4. Since the IR spectra on the day the suspensions are made and after mixing are close, the dispersed phase with nitrogen-containing groups on the surface acquires the original particle size and is evenly distributed over the volume of the dispersion medium, which confirms the ability of the suspensions to recover.

To illustrate the change in the spectrum of the suspension before and after recovery, Fig. 5 shows the IR spectra of a finely dispersed suspension based on PEPA and carbon copper-containing nanostructures with a concentration of 1 g / ml: control on the day of manufacture (a), on the fifth day of the beginning of separation before recovery (b ) and after recovery (c).

Peaks in the range of 1450-1650 cm ^-1 (Fig. 5) relate to deformation vibrations of NH ₂ groups (Gordon A., Ford R. Sputnik chemist. Physico-chemical properties, methods, bibliography. Translated from English by E. L. Rosenberg , S.I. Koppel, Mir Publishing House, 1976).

Peaks in the range of 1550-1650 cm ^-1 (Figure 5) relate to deformation vibrations of associated NH groups (L. A. Kazitsyna, NB Kupletskaya. Use of UV, IR and NMR spectroscopy in organic chemistry. 1971) .

The position and intensity of the peaks in the spectra of the initial suspension (Fig.5A) and after recovery (Fig.5B) were the same.

In the spectrum of the suspension, which did not undergo mixing on the 5th day of the onset of separation, an increase in the intensity of the bands of deformation vibrations of amino groups is observed, which indicates the formation of aggregates from particles of the dispersed phase (Fig.5b).

Similarly, the IR spectra of suspensions based on nickel (c, d) and cobalt-containing (e, f) nanostructures with a concentration of 1 g / ml (Fig. 3) obtained in Example 2 confirm the ability of these suspensions to be reduced.

Claims (2)

1. A method of manufacturing a finely dispersed organic suspension of carbon metal-containing nanostructures by the interaction of nanostructures and polyethylene polyamine, characterized in that the powder of carbon metal-containing nanostructures, which are nanoparticles of a 3d metal, such as copper, or cobalt, or nickel, stabilized in carbon nanostructures, is mechanically ground, then mechanically fray together with portion-injected polyethylene polyamine to achieve a nanostructure content of not more than 1 g / ml. 2. A finely dispersed organic suspension of carbon metal-containing nanostructures based on polyethylene polyamine, obtained by the method according to paragraph 1.

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