CN113956535A - Bead type one-dimensional heterogeneous nano composite material, preparation method and application thereof, and polymer-based wave-absorbing composite material - Google Patents
Bead type one-dimensional heterogeneous nano composite material, preparation method and application thereof, and polymer-based wave-absorbing composite material Download PDFInfo
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Abstract
The invention provides a bead type one-dimensional heterogeneous nano composite material, a preparation method and application thereof, and a polymer-based wave-absorbing composite material, and belongs to the technical field of wave-absorbing materials. According to the invention, MOFs are synthesized in situ and stringed in a one-dimensional inorganic insulating nano material, and the Co-C @ one-dimensional inorganic heterogeneous nano composite material is constructed after high-temperature calcination. The wave absorbing performance of the Co-C @ one-dimensional inorganic heterogeneous nano composite material can be regulated and controlled within a certain range by regulating the Co-C loading amount. On the basis, the one-dimensional heterogeneous nano composite material is filled into a polymer to prepare the polymer-based wave-absorbing composite material, and the rigid Co-C @ one-dimensional inorganic heterogeneous nano composite material with large length-diameter ratio is easy to disperse and lap joint in a polymer matrix to form a three-dimensional network structure, so that the wave-absorbing performance and the comprehensive performance of the composite material are improved.
Description
Technical Field
The invention relates to the technical field of wave-absorbing materials, in particular to a bead type one-dimensional heterogeneous nano composite material, a preparation method and application thereof and a polymer-based wave-absorbing composite material.
Background
With the rapid development of electronic technology, electronic equipment in life constantly influences the life of people, and electromagnetic pollution not only causes damage to electronic communication equipment, but also has great harm to human health. In order to overcome the pollution problem caused by electromagnetic radiation, electromagnetic wave absorbing materials are produced. The electromagnetic wave absorbing material has high absorption capacity and wide absorption bandwidth, and is favorable for reducing the harm of electromagnetic waves to electronic communication equipment and human health. On the other hand, electromagnetic absorption materials are also widely used in the military field, and have become an important index for measuring the military level of a country. Therefore, the development of the wave-absorbing material with excellent performance has great significance in military use, civil use and the like.
The traditional wave-absorbing materials comprise graphite, barium titanate, ferrite, silicon carbide and the like, but the application of the traditional wave-absorbing materials is limited due to the defects of narrow absorption band and high density. In recent years, porous carbon nanocomposites prepared from MOFs (Metal organic Framework compounds, english name Metal organic Framework) have attracted attention. The MOFs material is an organic-inorganic hybrid material formed by self-assembling metal ions, clusters and organic ligands, adjacent metal ions are connected through the organic ligands, the structure is neat and ordered, and the MOFs material has the characteristics of large specific surface area, high porosity and the like. MOFs precursors can be converted to metal/carbon composites by carbonization at different temperatures. The porous carbon material formed after the MOFs are calcined converts the insulating MOFs into a conductive material, and magnetic metal or metal oxide cluster nano particles formed in situ in the porous carbon material can widely adjust magnetic loss and dielectric loss, so that multiple reflection loss of electromagnetic waves in an absorber is greatly promoted, and the absorption effect of the electromagnetic waves is favorably improved. However, the resistivity of the MOFs-derived carbon-based material is greatly different from that of air, thereby causing impedance mismatching, and the metal particles contained in the MOFs-derived carbon-based material affect the chemical stability thereof, thereby limiting the application of the MOFs-derived carbon-based material in the field of electromagnetic wave absorption. In addition, the porous carbon material formed after the MOFs are calcined is a spherical powder material, and is not easy to disperse in a polymer matrix and other matrixes, if the filling amount is too small, a large number of conductive carbon particles in the porous carbon material cannot be in close contact, a large and wide conductive path cannot be formed, and a conductive network cannot be constructed, so that the conductive network formed in the polymer matrix needs a large filling amount (more than 60 wt%), the cost of the material is increased, and the original mechanical property and the processing flow property of the polymer matrix material are reduced.
Disclosure of Invention
The invention aims to provide a beaded one-dimensional heterogeneous nano composite material, a preparation method and application thereof, and a polymer matrix wave-absorbing composite material.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a bead type one-dimensional heterogeneous nano composite material, which comprises a one-dimensional inorganic insulating nano material and Co-C particles strung on the one-dimensional inorganic insulating nano material, wherein the Co-C particles are prepared by sintering a metal organic framework ZIF-67, and the Co-C particles and the one-dimensional inorganic insulating nano material form a bead type structure; the one-dimensional inorganic insulating nano material comprises a boron nitride nanotube, a boron nitride whisker or an aluminum oxide nanowire.
Preferably, the diameter of the boron nitride nanotube is 30-50 nm, the length-diameter ratio is 180-300, and the specific surface area is 65-75 m2(ii)/g, average pore radius of 10.86 nm; the mass ratio of the one-dimensional inorganic insulating nano material to the Co-C particles is 1 (1-3).
The invention provides a preparation method of a bead type one-dimensional heterogeneous nano composite material in the technical scheme, which comprises the following steps:
mixing a one-dimensional inorganic insulating nano material, a cobalt source, a surfactant, 2-methylimidazole and an organic solvent, and carrying out in-situ synthesis to obtain a ZIF-67@ one-dimensional inorganic insulating nano composite material; the one-dimensional inorganic insulating nano material comprises a boron nitride nanotube, a boron nitride whisker or an aluminum oxide nanowire;
and sintering the ZIF-67@ one-dimensional inorganic insulating nano composite material to obtain the beaded one-dimensional heterogeneous nano composite material.
Preferably, the cobalt source comprises cobalt nitrate; the molar ratio of the cobalt source to the one-dimensional inorganic insulating nano material is 1 (0.1-1.2).
Preferably, the surfactant comprises polyvinylpyrrolidone, sodium stearyl sulfate, sodium dodecylbenzenesulfonate or sodium dodecyl sulfate.
Preferably, the molar ratio of the surfactant to the one-dimensional inorganic insulating nano material is 1 (20-800).
Preferably, the molar ratio of the 2-methylimidazole to the cobalt source is 1 (0.05-0.2).
Preferably, the temperature of the in-situ synthesis is 25-30 ℃, and the time is 3-8 h; the sintering temperature is 500-900 ℃, and the sintering time is 2-5 h.
The invention provides an application of the beaded one-dimensional heterogeneous nano composite material in the technical scheme or the beaded one-dimensional heterogeneous nano composite material prepared by the preparation method in the technical scheme in the field of microwave absorption.
The invention provides a polymer-based wave-absorbing composite material, which comprises a bead-string type one-dimensional heterogeneous nano composite material and a polymer matrix material which are blended; the bead type one-dimensional heterogeneous nano composite material is the bead type one-dimensional heterogeneous nano composite material prepared by the technical scheme or the preparation method of the technical scheme.
The invention provides a bead type one-dimensional heterogeneous nano composite material, which comprises a one-dimensional inorganic insulating nano material and Co-C particles strung on the one-dimensional inorganic insulating nano material, wherein the Co-C particles are prepared by sintering a metal organic framework ZIF-67, and the Co-C particles and the one-dimensional inorganic insulating nano material form a bead type structure; the one-dimensional inorganic insulating nano material comprises a boron nitride nanotube, a boron nitride whisker or an aluminum oxide nanowire. According to the invention, the carbon-based material particles derived from MOFs are strung on the one-dimensional inorganic insulating nano material, disordered Co-C particles are orderly arranged on the one-dimensional inorganic insulating nano material by virtue of the supporting effect of the rigid one-dimensional inorganic insulating nano material to form a stable three-dimensional conductive network, the Co-C particles can be uniformly distributed in the network and are tightly combined with the one-dimensional inorganic insulating nano material and are not easy to separate, meanwhile, the widely distributed one-dimensional nano materials can be mutually lapped to form polygonal holes which are different in size and very stable, the polygonal holes can support the carbon-based material Co-C particles and can form a complex conductive path, the dielectric loss and the magnetic loss of the composite material are enhanced, and the microwave absorption performance is improved.
According to the invention, an insulated boron nitride nanotube, a boron nitride whisker or an alumina nanowire is used as a support, Co-C particles are strung to form a Co-C @ one-dimensional heterogeneous nano composite material, and the Co-C @ one-dimensional heterogeneous nano composite material with a large length-diameter ratio enables the Co-C @ one-dimensional heterogeneous nano composite material to be easily dispersed and lapped in a polymer matrix, so that a three-dimensional conductive network is constructed, the dielectric loss and the magnetic loss of the Co-C @ one-dimensional heterogeneous nano composite material are enhanced, and the microwave absorption performance is improved; the boron nitride nanotube is an insulating hollow material, has high rigidity, is easy to disperse to form a passage, dissipates microwaves for many times in the hollow nanotube and improves the microwave absorption performance.
The invention can adjust the wave absorbing performance of the bead type one-dimensional heterogeneous nano composite material by adjusting and controlling the loading capacity of the Co-C particles on the one-dimensional nano material, thereby obtaining the one-dimensional heterogeneous nano composite material with adjustable and controllable microwave absorbing performance.
The invention provides a preparation method of a beaded one-dimensional heterogeneous nano composite material, which adopts an in-situ synthesis method to load a metal organic framework compound ZIF-67 on a one-dimensional inorganic insulating nano material in situ, a ZIF-67 crystal grows on the one-dimensional inorganic insulating nano material in a series-lapping mode to form a beaded structure of the ZIF-67@ one-dimensional inorganic insulating nano material, and the organic framework in the ZIF-67 is decomposed into a porous carbon material, Co, through sintering2+Is reduced into Co to form Co-C which is strung on the one-dimensional inorganic insulating nano material to prepare the beaded Co-C @ one-dimensional inorganic insulating nano material heterogeneous nano composite material. The bead-type one-dimensional heterogeneous nano composite material not only endows the insulated boron nitride nanotube, the boron nitride whisker and the alumina nanowire with high conductivity (the high conductivity is endowed by the carbon particles and the metal cobalt particles, and the Co-C particles are strung on the one-dimensional nano material to form a conductive path), but also generates interface polarization loss and multiple reflection loss due to the special bead-type structure, combines the magnetic loss of the magnetic Co particles, the conductive loss of the carbon material and the dielectric loss of the one-dimensional inorganic insulating nano material, and greatly increases the microwave absorption capacity of the material in a multiple energy dissipation mode, so that the bead-type one-dimensional heterogeneous nano composite material is a brand new high-wave absorption composite material, and has a coating structure with large specific surface area (150-430 m) of mutual strung and has a brand new coating structure2The microwave absorbing material has the characteristics of a,/g) and a small pore radius (2.1-5.5 nm), and the like, and the existence of the pores increases the path of microwave reflection in the material, thereby improving the wave absorbing performance of the material. The one-dimensional inorganic insulating nano material is formed by connecting a plurality of ZIF-67 particles in series to form a bead-string structure, and the good mechanical strength and rigidity of the one-dimensional inorganic insulating nano material ensure that the formed Co-C @ one-dimensional inorganic insulating nano material heterogeneous nano composite material is not easy to agglomerate and is easier to form a continuous conductive network in a polymer matrix, and the composite material can achieve more excellent microwave absorption performance than the Co-C material under the same mass under the condition of lower filling amount. Meanwhile, the high thermal conductivity of the one-dimensional inorganic insulating nano material reduces adverse effects caused by eddy current effect heating in the wave absorbing process. The method expands the application of the one-dimensional inorganic insulating nano material, improves the application value of MOFs and the Co-C composite material of the calcination product thereof, and provides a new idea for solving the electromagnetic pollution.
The one-dimensional heterogeneous nano composite material prepared by the invention is non-toxic and pollution-free, does not generate harmful gas to human bodies in the preparation process, and has the advantages of simple and convenient operation process, short synthesis period, environmental protection, safety and controllable appearance.
The beaded one-dimensional heterogeneous nano composite material is used in a polymer matrix, the reflection loss of the polymer matrix composite material is adjustable within the range of-20 to-70 dB by adjusting the loading capacity of Co-C on the one-dimensional nano material and the addition of the one-dimensional heterogeneous nano composite material in the polymer matrix, the wave absorption is adjustable, the beaded one-dimensional heterogeneous nano composite material has good application value, and a new thought is provided for the innovative development of microwave absorbing materials.
The beaded one-dimensional heterogeneous nano composite material is used in a polymer matrix, the filling amount of the composite material in the polymer matrix can be as low as 10%, the beaded one-dimensional heterogeneous nano composite material has a multiple loss mechanism, multiple dissipation of microwaves is formed by the conductive loss of a carbon material, the magnetic loss of cobalt particles and the dielectric loss of a one-dimensional nano material, and simultaneously, multiple interface polarization and microwave loss can be generated due to multiple interfaces formed by a beaded structure; and Co-C particles are serially lapped on the one-dimensional nano material in a bead-string structure and filled into the polymer matrix to form a three-dimensional conductive network, so that the dissipation of microwaves is greatly enhanced, and the low filling amount and high wave-absorbing performance are realized.
Drawings
FIG. 1 is an SEM image of a Co-C material prepared in comparative example 1;
FIG. 2 is an SEM image of a ZIF-67@ BNNT one-dimensional nanocomposite prepared in example 1;
FIG. 3 is an SEM image of one-dimensional heterogeneous Co-C @ BNNT nanocomposite prepared in example 1;
FIG. 4 is the electromagnetic wave reflection curve of the Co-C @ BNNT one-dimensional heterogeneous nanocomposite prepared in example 1 at a matching thickness of 3 mm.
Detailed Description
The invention provides a bead type one-dimensional heterogeneous nano composite material, which comprises a one-dimensional inorganic insulating nano material and Co-C particles strung on the one-dimensional inorganic insulating nano material, wherein the Co-C particles are prepared by sintering a metal organic framework ZIF-67, and the Co-C particles and the one-dimensional inorganic insulating nano material form a bead type structure; the one-dimensional inorganic insulating nano material comprises a boron nitride nanotube, a boron nitride whisker or an aluminum oxide nanowire.
In the present invention, the starting materials or reagents required are commercially available products well known to those skilled in the art unless otherwise specified.
The bead-type one-dimensional heterogeneous nano composite material provided by the invention comprises a one-dimensional inorganic insulating nano material, wherein the one-dimensional inorganic insulating nano material comprises Boron Nitride Nanotubes (BNNT), Boron Nitride Whiskers (BNW) or aluminum oxide nanowires (ANW).
In the invention, the diameter of the boron nitride nanotube is preferably 30-50 nm, the length-diameter ratio is preferably 180-300, and the specific surface area is preferably 65-75 m2The average pore radius is preferably 10.86 nm; the diameter of the boron nitride whisker is preferably 100-500 nm, the length-diameter ratio is preferably 10-100, and the specific surface area is preferably 10-15 m2(ii)/g; the diameter of the aluminum oxide nanowire is preferably 2-8 nm, the length-diameter ratio is preferably 200-800, and the specific surface area is preferably 150-160 m2/g。
According to the invention, the load rate of MOFs is improved by virtue of the high specific surface area, the ion adsorption capacity and the excellent mechanical property of the one-dimensional nano material, and the wave absorbing performance of the Co-C @ one-dimensional inorganic heterogeneous nano composite material is adjustable within a certain range by adjusting the load capacity of ZIF-67. And the Co-C @ one-dimensional inorganic heterogeneous nano composite material is easy to construct a three-dimensional network structure by the support of the rigid one-dimensional inorganic insulating nano material, so that the stability and the dispersibility of the composite material are improved. The insulating property and the high contact area of the one-dimensional inorganic insulating nano material optimize impedance matching, are beneficial to the generation of electronic polarization and interface polarization, and are beneficial to improving the dielectric loss and magnetic loss capacity of MOFs particles; a complex microwave transmission channel is constructed by the Co-C and the one-dimensional inorganic insulating nano material, so that energy dissipation generated by microwaves in the material is facilitated; the addition of the one-dimensional inorganic insulating nano material effectively improves the heat conductivity and the corrosion resistance of the material, effectively reduces the influence caused by the vortex effect, and avoids the structural damage and the reduction of the wave absorbing performance caused by the vortex effect.
The bead-type one-dimensional heterogeneous nano composite material provided by the invention comprises Co-C particles which are strung on the one-dimensional inorganic insulating nano material; the Co-C particles are made of a metal organic framework ZIF-67 through sintering, and the Co-C particles and the one-dimensional inorganic insulating nano material form a bead-string structure.
In the bead-type one-dimensional heterogeneous nano composite material, an inorganic insulating one-dimensional nano material, conductive porous carbon and metal cobalt form a heterogeneous structure.
In the invention, the metal organic framework ZIF-67 has a regular dodecahedron microstructure, and the Co-C material formed by high-temperature sintering has abundant bulges on the surface, contains magnetic metal Co inside and is microporous.
The process for preparing the Co-C particles by sintering the metal organic framework ZIF-67 is not particularly limited, and may be performed according to a process well known in the art.
In the invention, the mass ratio of the one-dimensional inorganic insulating nano material to the Co-C particles is preferably 1 (1-3), more preferably 1: (1.3-2.6).
In the invention, the specific surface area of the Co-C particles is preferably 100-300 m2(ii) g, more preferably 200m2The pore radius is preferably 3-4 nm, more preferably 3.76nm, and the conductivity is preferably 4-9S/cm, more preferably 8S/cm.
The invention provides a preparation method of a bead type one-dimensional heterogeneous nano composite material in the technical scheme, which comprises the following steps:
mixing a one-dimensional inorganic insulating nano material, a cobalt source, a surfactant, 2-methylimidazole and an organic solvent, and carrying out in-situ synthesis to obtain a ZIF-67@ one-dimensional inorganic insulating nano composite material; the one-dimensional inorganic insulating nano material comprises a boron nitride nanotube, a boron nitride whisker or an aluminum oxide nanowire;
and sintering the ZIF-67@ one-dimensional inorganic insulating nano composite material to obtain the beaded one-dimensional heterogeneous nano composite material.
The preparation method comprises the steps of mixing a one-dimensional inorganic insulating nano material, a cobalt source, a surfactant, 2-methylimidazole and an organic solvent, and carrying out in-situ synthesis to obtain the ZIF-67@ one-dimensional inorganic insulating nano composite material. In the present invention, the cobalt source preferably comprises cobalt nitrate, more preferably cobalt nitrate hexahydrate; the mol ratio of the cobalt source to the one-dimensional inorganic insulating nano material is preferably 1 (0.1-1.2), more preferably 1 (0.2-1), and further preferably 1 (0.875-1).
In the invention, the surfactant preferably comprises polyvinylpyrrolidone, sodium octadecyl sulfate, sodium dodecyl benzene sulfonate or sodium dodecyl sulfate, and the molar ratio of the surfactant to the one-dimensional inorganic insulating nano material is preferably 1 (20-800), more preferably 1 (32-700), and further preferably 1 (140-500). The invention utilizes the surfactant to promote the combination of cobalt ions and the one-dimensional nano material, so that the cobalt ions are wrapped on the one-dimensional nano material, and the ZIF-67 crystal is grown in situ.
In the present invention, the molar ratio of the 2-methylimidazole to the cobalt source is preferably 1 (0.05 to 0.2), and more preferably 1: 0.1.
In the present invention, the organic solvent is preferably anhydrous methanol; the invention has no special limitation on the dosage of the organic solvent, and can ensure that materials are fully mixed and the reaction is smoothly carried out.
In the present invention, the mixing process of the one-dimensional inorganic insulating nanomaterial, the cobalt source, the surfactant, the 2-methylimidazole, and the organic solvent is preferably: dispersing a one-dimensional inorganic insulating nano material in a first part of organic solvent, dissolving a surfactant in a second part of organic solvent, and mixing and stirring the obtained surfactant solution and the one-dimensional inorganic insulating nano material dispersion liquid uniformly to obtain a first solution; dissolving a cobalt source in the third part of organic solvent, uniformly oscillating, and adding the obtained cobalt source solution into the first solution to obtain a second solution; dissolving 2-methylimidazole in the residual organic solvent, dropwise adding the obtained 2-methylimidazole solution into the second solution, and uniformly stirring to obtain a mixed material. The stirring speed is not specially limited, and the materials can be uniformly mixed.
In the invention, the concentration of the cobalt source solution is preferably 30-85 mmol/L, and more preferably 40 mmol/L; the concentration of the 2-methylimidazole solution is preferably 700-900 mmol/L, and more preferably 800 mmol/L.
In the invention, the temperature of the in-situ synthesis is 25-30 ℃, more preferably 28 ℃, and the time is preferably 3-8 h, more preferably 6 h; the in-situ synthesis is preferably carried out under the stirring condition and the standing condition in sequence, the time ranges of the stirring condition and the standing condition are not specially limited, and the in-situ synthesis is adjusted according to actual requirements to meet the total synthesis time.
After the in-situ synthesis is completed, the product is preferably subjected to centrifugal separation, drying and grinding in sequence to obtain the ZIF-67@ one-dimensional inorganic insulating nano composite material. In the present invention, the drying is preferably performed in vacuum, and the drying temperature is preferably 60 ℃. The process of centrifugation and grinding is not particularly limited in the present invention, and may be performed according to a process well known in the art.
After the ZIF-67@ one-dimensional inorganic insulating nano composite material is obtained, the invention sinters the ZIF-67@ one-dimensional inorganic insulating nano composite material to obtain the beaded one-dimensional heterogeneous nano composite material. The invention preferably performs the sintering in a muffle furnace; the sintering temperature is preferably 500-900 ℃, and more preferably 600-800 ℃; the time is preferably 2 to 5 hours, and more preferably 3 hours. The invention controls the structure and the composition of the product through the sintering temperature and the protective gas, so that the product has good electromagnetic wave absorption effect.
Compared with the prior art, the invention has the following advantages:
(1) according to the invention, Co-C particles are serially lapped on the one-dimensional inorganic insulating nano material, and the large length-diameter ratio of the one-dimensional inorganic insulating nano material enables the one-dimensional inorganic insulating nano material to easily construct a three-dimensional conductive network in a polymer matrix, so that low filling and high absorption can be realized, and the defects that the Co-C particles are filled into the polymer matrix, the particle size is small, the particles are easy to agglomerate, a conductive path is not easy to form in the polymer matrix, and the Co-C particles can form the conductive network only by needing large filling amount, so that the composite material has poor wave-absorbing performance are overcome.
(2) Improve impedance matching, strengthen the microwave absorption: Co-C has good conductivity and magnetic permeability, so that the conductivity loss and the magnetic loss can be generated, when the resistivity is too much different from that of air, electromagnetic waves are reflected when being emitted to the surface of the material, and the material with high conductivity enables the electromagnetic waves to be reflected on the surface of the material in a large amount and not to effectively enter the material, so that impedance mismatching is caused, and the wave absorbing performance is limited. The invention compounds the insulated one-dimensional inorganic nano material with Co-C with higher conductivity, reduces the difference between the electrical resistivity of the Co-C and the air, optimizes impedance matching and enhances the absorption of the composite material to electromagnetic waves. The Co-C @ one-dimensional inorganic insulating nano composite material integrates the conductance loss, the dielectric loss and the magnetic loss, and gives consideration to impedance matching, so that the Co-C @ one-dimensional inorganic insulating nano composite material has excellent wave absorbing performance. Moreover, because the Co-C particles are small, the structure is high, and the Co-C particles have a plurality of gaps, a plurality of reflection points can be formed on the electromagnetic waves, and the electromagnetic waves are scattered for a plurality of times to consume energy, thereby achieving the purpose of absorbing the electromagnetic waves.
(3) Co-C is threaded on the one-dimensional inorganic insulating nano material, a local conductive network is formed in the material, and the thermal conductivity of the material is effectively improved (the maximum thermal conductivity coefficient can reach 1.42 W.m)-1·K-1The thermal conductivity of the pure boron nitride filling system is measured to be 1.13 W.m under the same filling ratio-1·K-1) Because the lapping also forms a heat conducting network, the one-dimensional inorganic insulating nano material adopted by the invention has very high large thermal coefficient (20-300 W.m)-1·K-1) Therefore, the heat brought by energy loss generated by absorbing electromagnetic waves can be effectively dissipated, and the safety and stability of the material are improved.
In the invention, the invention provides the application of the beaded type one-dimensional heterogeneous nano composite material prepared by the preparation method in the technical scheme or the application of the beaded type one-dimensional heterogeneous nano composite material prepared by the preparation method in the microwave absorption field. The method of the present invention is not particularly limited, and the method may be applied according to a method known in the art.
The invention provides a polymer-based wave-absorbing composite material, which comprises a bead-string type one-dimensional heterogeneous nano composite material and a polymer matrix material which are blended; the bead type one-dimensional heterogeneous nano composite material is the bead type one-dimensional heterogeneous nano composite material prepared by the technical scheme or the preparation method of the technical scheme. In the present invention, the polymer matrix material preferably comprises Thermoplastic Polyurethane (TPU), polyvinyl butyral (PVB), or polyvinylidene fluoride (PVDF); the mass ratio of the beaded one-dimensional heterogeneous nano composite material to the polymer matrix material is preferably 1: (1 to 9), more preferably 1: (2-4).
In the invention, the preparation method of the polymer-based wave-absorbing composite material preferably comprises the following steps: mixing the bead type one-dimensional heterogeneous nano composite material with the polymer material dispersion liquid, and carrying out tape casting on the obtained mixture to form a film so as to obtain the polymer-based composite material.
In the present invention, the solvent used for the polymer material dispersion is preferably N, N-Dimethylformamide (DMF). The invention has no special limit on the concentration of the polymer material dispersion liquid, and can be obtained by fully mixing the polymer material and the bead-type one-dimensional heterogeneous nano composite material.
In the invention, the process of mixing the beaded one-dimensional heterogeneous nano composite material and the polymer material dispersion liquid is preferably carried out under the stirring condition, the stirring speed is not particularly limited, and the materials can be fully mixed.
In the present invention, the film formation is preferably performed on a substrate, and the present invention preferably performs film casting on a substrate, which is preferably a glass plate or a stainless steel plate; the present invention is not particularly limited with respect to the specific type and source of the substrate, and any commercially available substrate known in the art may be used.
The process of the casting film formation and the thickness of the obtained film are not particularly limited in the present invention, and the film formation is performed according to the process well known in the art, and the film thickness is determined according to the material amount.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The following examplesThe Boron Nitride Nanotube (BNNT) has a diameter of 30-50 nm, a length-diameter ratio of 180-300, and a specific surface area of 65-75 m2(ii)/g, average pore radius of 10.86 nm; the boron nitride crystal whisker (BNW) has the diameter of 100-500 nm, the length-diameter ratio of 10-100 and the specific surface area of 10-15 m2(ii)/g; the diameter of the aluminum oxide nanowire (ANW) is 2-8 nm, the length-diameter ratio is 200-800, and the specific surface area is 150-160 m2/g。
Example 1
Dispersing 0.7mmol of boron nitride nanotubes in 60mL of anhydrous methanol, dispersing 0.005mmol of polyvinylpyrrolidone in 60mL of anhydrous methanol, and mixing the two obtained dispersions to obtain a first solution; dissolving 0.8mmol of cobalt nitrate hexahydrate in 20mL of anhydrous methanol, uniformly stirring, and adding the mixture into the first solution to obtain a second solution; rapidly stirring 8mmol of 2-methylimidazole in 10mL of anhydrous methanol, gradually dropping the second solution to obtain a third solution, stirring for 3h, standing and aging at 28 ℃ for 3h, carrying out in-situ synthesis, centrifuging the obtained product, drying the purple precipitate in a 60 ℃ oven in vacuum, grinding the product into powder, placing the obtained ZIF-67@ BNNT one-dimensional nano composite material in a muffle furnace, and sintering the product at 800 ℃ for 3h to obtain a Co-C @ BNNT one-dimensional heterogeneous nano composite material, wherein the mass ratio of the one-dimensional inorganic insulating nano material to the Co-C particles is 1: 2.6.
Example 2
The only difference from example 1 is: and replacing 0.005mmol of polyvinylpyrrolidone with 0.001mmol of polyvinylpyrrolidone to obtain the Co-C @ BNNT heterogeneous nano composite material, wherein the mass ratio of the one-dimensional inorganic insulating nano material to the Co-C particles is 1:1.3 in the same manner as in example 1.
Example 3
The only difference from example 1 is: sintering at 600 ℃ for 3h to obtain the Co-C @ BNNT one-dimensional nano composite material.
Example 4
The only difference from example 1 is: and replacing 0.7mmol of boron nitride nanotubes with 0.16mmol of alumina nanowires to obtain the Co-C @ ANW one-dimensional heterogeneous nano composite material, wherein the mass ratio of the one-dimensional inorganic insulating nano material to the Co-C particles is 1:2.6 in the same manner as in example 1.
Comparative example 1
Dissolving 0.8mmol of cobalt nitrate hexahydrate in 140mL of anhydrous methanol, and uniformly stirring to obtain a solution A; placing 8mmol of 2-methylimidazole in 10mL of anhydrous methanol, rapidly stirring and gradually dropping the solution A to obtain a solution B; stirring the solution B for 3 hours, standing and aging for 3 hours, centrifuging, drying the obtained precipitate in an oven at 60 ℃ in vacuum, grinding the dried precipitate into powder, and sintering the powder in a muffle furnace at 800 ℃ for 3 hours to obtain the Co-C material.
In the following application examples, the filler ratio is the mass ratio of the one-dimensional heterogeneous nanocomposite to the polymer matrix.
Application example 1
The Co-C @ BNNT one-dimensional heterogeneous nanocomposite prepared in example 1 was added to the TPU matrix at a filler ratio of 1: 2: and dissolving the TPU in DMF to ensure that the concentration of the TPU is 91mmol/L, adding the Co-C @ BNNT one-dimensional heterogeneous nano composite material prepared in the example 1, stirring uniformly, pouring into a casting mould for molding, and drying to form a film.
Application example 2
The Co-C @ BNNT heterogeneous nanocomposite prepared in example 2 was added to a PVDF matrix at a filler ratio of 1:2, and the composite was prepared according to the method of application example 1.
Application example 3
The Co-C @ BNNT one-dimensional nanocomposite prepared in example 3 was added to a TPU matrix at a filler ratio of 1:2, and the composite was prepared according to the method of application example 1.
Application example 4
The Co-C @ BNNT heterogeneous nanocomposite prepared in example 1 was added to a TPU matrix at a filler ratio of 1:1 and made into a composite as in application example 1.
Application example 5
The Co-C @ ANW one-dimensional heterogeneous nanocomposite prepared in example 4 was added to a PVB matrix at a filler ratio of 1:2, and the composite was made according to the method of application example 1.
Application example 6
The Co/C @ BNNT one-dimensional heterogeneous nanomaterial prepared in example 1 was added to a TPU matrix at a filler ratio of 1:9, and a composite was prepared according to the method of application example 1.
Comparative application example 1
The Co-C material prepared in comparative example 1 was added to a TPU matrix at a 1:2 filler ratio to make a polymer matrix composite as in application example 1.
Comparative application example 2
The boron nitride nanotubes were added to the TPU matrix at a filler ratio of 1:2, and the polymer matrix composite was prepared according to the method of application example 1.
Comparative application example 3
The pure TPU matrix was used as comparative application example 3.
Characterization and Performance testing
1) SEM test of the Co-C material prepared in comparative example 1, the obtained result is shown in FIG. 1; as shown in FIG. 1, Co-C is a powder material which is similar to a sphere and is easy to agglomerate. The structure of the Co-C material prepared in comparative example 1 was measured by the BET method, and the result showed that the Co-C material had a specific surface area of 200m2(ii)/g, average pore radius of 3.76 nm; and the conductivity is measured by referring to a four-probe method in the method for measuring the powder conductivity in GBT 30835-.
2) SEM test of the ZIF-67@ BNNT one-dimensional nanocomposite prepared in example 1 is carried out, and the obtained result is shown in FIG. 2; as can be seen from FIG. 2, ZIF-67 clusters on boron nitride nanotubes.
3) SEM test of the Co-C @ BNNT one-dimensional heterogeneous nano composite material prepared in example 1 is carried out, and the obtained result is shown in figure 3; as can be seen from FIG. 3, the Co-C formed by decomposition after the ZIF-67 carbonization still strung on the boron nitride nanotubes, indicating that the beaded composite material was successfully prepared.
4) The BET test and the conductivity test are carried out on the Co-C @ BNNT nanotube prepared in example 1, and the result shows that the specific surface area is 150-200 m2(ii)/g, average pore radius of 3nm, and conductivity of 4S/cm.
5) FIG. 4 is the microwave reflection plot of the Co-C @ BNNT one-dimensional heterogeneous nanocomposite prepared in example 1 at a matched 3mm thickness; as can be seen from fig. 4, when the matching thickness is 3mm, the maximum wave-absorbing effect is-54.2 dB in the frequency range of 8-12.4 GHz.
6) The materials of application examples 1-6 and comparative application examples 1-3 are subjected to performance testing, the wave-absorbing performance is tested according to a method for measuring the shielding effectiveness of materials SJ 20524-; the thermal conductivity is measured according to the flash method described in GB/T22588-.
TABLE 1 Performance data for materials of application examples 1-6 and comparative application examples 1-3
As shown in Table 1, in the case of a low filler ratio (beaded Co-C @ BNNT filler: polymer: 1:2), the microwave absorption performance of the polymer-based composite material was greatly improved, and the maximum wave absorption effect R was exhibitedL-54.2 dB; and under the condition of lower filler ratio (beaded Co-C @ BNNT filler: polymer: 1:9), the maximum wave absorption effect RL is-15.4 dB, and the commercial application requirement of the wave absorbing material can be met (generally R is RL<-10dB), meanwhile, the polymer matrix composite material prepared by the invention has excellent thermal conductivity, and overcomes the defect of poor heat dissipation of common wave absorbing materials.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A bead type one-dimensional heterogeneous nano composite material comprises a one-dimensional inorganic insulating nano material and Co-C particles which are strung on the one-dimensional inorganic insulating nano material, wherein the Co-C particles are made by sintering a metal organic framework ZIF-67, and the Co-C particles and the one-dimensional inorganic insulating nano material form a bead type structure; the one-dimensional inorganic insulating nano material comprises a boron nitride nanotube, a boron nitride whisker or an aluminum oxide nanowire.
2. The beaded one-dimensional heterogeneous nanocomposite material as claimed in claim 1, wherein the boron nitride nanotube has a diameter of 30 to 50nm, an aspect ratio of 180 to 300, and a specific surface area of 65 to 75m2(ii)/g, average pore radius of 10.86 nm; the mass ratio of the one-dimensional inorganic insulating nano material to the Co-C particles is 1 (1-3).
3. The method for preparing the beaded one-dimensional heterogeneous nanocomposite material of claim 1 or 2, comprising the steps of:
mixing a one-dimensional inorganic insulating nano material, a cobalt source, a surfactant, 2-methylimidazole and an organic solvent, and carrying out in-situ synthesis to obtain a ZIF-67@ one-dimensional inorganic insulating nano composite material; the one-dimensional inorganic insulating nano material comprises a boron nitride nanotube, a boron nitride whisker or an aluminum oxide nanowire;
and sintering the ZIF-67@ one-dimensional inorganic insulating nano composite material to obtain the beaded one-dimensional heterogeneous nano composite material.
4. The method of claim 3, wherein the cobalt source comprises cobalt nitrate; the molar ratio of the cobalt source to the one-dimensional inorganic insulating nano material is 1 (0.1-1.2).
5. The method of claim 3, wherein the surfactant comprises polyvinylpyrrolidone, sodium stearyl sulfate, sodium dodecylbenzenesulfonate or sodium dodecyl sulfate.
6. The preparation method according to claim 5, wherein the molar ratio of the surfactant to the one-dimensional inorganic insulating nanomaterial is 1 (20-800).
7. The method according to claim 3 or 4, wherein the molar ratio of the 2-methylimidazole to the cobalt source is 1 (0.05 to 0.2).
8. The preparation method according to claim 3, wherein the temperature of the in-situ synthesis is 25-30 ℃ and the time is 3-8 h; the sintering temperature is 500-900 ℃, and the sintering time is 2-5 h.
9. The beaded one-dimensional heterogeneous nano-composite material of claim 1 or 2 or the beaded one-dimensional heterogeneous nano-composite material prepared by the preparation method of any one of claims 3 to 8, and the application thereof in the field of microwave absorption.
10. A polymer-based wave-absorbing composite material comprises a bead-type one-dimensional heterogeneous nano composite material and a polymer matrix material which are blended; the beaded one-dimensional heterogeneous nano composite material is the beaded one-dimensional heterogeneous nano composite material of claim 1 or 2 or the beaded one-dimensional heterogeneous nano composite material prepared by the preparation method of any one of claims 3 to 8.
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