CN116355586B - Composite shielding material and preparation method thereof - Google Patents
Composite shielding material and preparation method thereof Download PDFInfo
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- CN116355586B CN116355586B CN202111633649.3A CN202111633649A CN116355586B CN 116355586 B CN116355586 B CN 116355586B CN 202111633649 A CN202111633649 A CN 202111633649A CN 116355586 B CN116355586 B CN 116355586B
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- 239000002131 composite material Substances 0.000 title claims abstract description 91
- 239000000463 material Substances 0.000 title claims abstract description 85
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- 229910052751 metal Inorganic materials 0.000 claims abstract description 162
- 239000002184 metal Substances 0.000 claims abstract description 162
- 229920001690 polydopamine Polymers 0.000 claims abstract description 66
- VYFYYTLLBUKUHU-UHFFFAOYSA-N dopamine Chemical compound NCCC1=CC=C(O)C(O)=C1 VYFYYTLLBUKUHU-UHFFFAOYSA-N 0.000 claims abstract description 50
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 49
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 48
- 150000003839 salts Chemical class 0.000 claims abstract description 40
- 239000012621 metal-organic framework Substances 0.000 claims abstract description 30
- 229960003638 dopamine Drugs 0.000 claims abstract description 25
- 238000001354 calcination Methods 0.000 claims abstract description 24
- 150000001875 compounds Chemical class 0.000 claims abstract description 22
- 239000013110 organic ligand Substances 0.000 claims abstract description 18
- 239000002904 solvent Substances 0.000 claims abstract description 18
- 239000012298 atmosphere Substances 0.000 claims abstract description 5
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 33
- 238000006243 chemical reaction Methods 0.000 claims description 27
- LXBGSDVWAMZHDD-UHFFFAOYSA-N 2-methyl-1h-imidazole Chemical compound CC1=NC=CN1 LXBGSDVWAMZHDD-UHFFFAOYSA-N 0.000 claims description 24
- 239000003638 chemical reducing agent Substances 0.000 claims description 21
- 239000011247 coating layer Substances 0.000 claims description 20
- 239000010410 layer Substances 0.000 claims description 20
- 238000000034 method Methods 0.000 claims description 17
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 claims description 14
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 claims description 14
- 239000008103 glucose Substances 0.000 claims description 14
- 239000011975 tartaric acid Substances 0.000 claims description 14
- 235000002906 tartaric acid Nutrition 0.000 claims description 14
- 230000035484 reaction time Effects 0.000 claims description 13
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 12
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 claims description 10
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 10
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 claims description 10
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 9
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 9
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical group O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 229910021645 metal ion Inorganic materials 0.000 claims description 7
- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 claims description 6
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 6
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical group [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 6
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 claims description 6
- 239000007983 Tris buffer Substances 0.000 claims description 6
- 239000002253 acid Substances 0.000 claims description 6
- 239000000872 buffer Substances 0.000 claims description 6
- 239000012153 distilled water Substances 0.000 claims description 5
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 4
- 239000008367 deionised water Substances 0.000 claims description 4
- 229910021641 deionized water Inorganic materials 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- ZCUJYXPAKHMBAZ-UHFFFAOYSA-N 2-phenyl-1h-imidazole Chemical compound C1=CNC(C=2C=CC=CC=2)=N1 ZCUJYXPAKHMBAZ-UHFFFAOYSA-N 0.000 claims description 3
- ULKLGIFJWFIQFF-UHFFFAOYSA-N 5K8XI641G3 Chemical compound CCC1=NC=C(C)N1 ULKLGIFJWFIQFF-UHFFFAOYSA-N 0.000 claims description 3
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 3
- 125000003172 aldehyde group Chemical group 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 claims description 3
- 239000006172 buffering agent Substances 0.000 claims description 3
- 235000015165 citric acid Nutrition 0.000 claims description 3
- 229910000402 monopotassium phosphate Inorganic materials 0.000 claims description 3
- 235000019796 monopotassium phosphate Nutrition 0.000 claims description 3
- 229910017604 nitric acid Inorganic materials 0.000 claims description 3
- PJNZPQUBCPKICU-UHFFFAOYSA-N phosphoric acid;potassium Chemical compound [K].OP(O)(O)=O PJNZPQUBCPKICU-UHFFFAOYSA-N 0.000 claims description 3
- 229910000030 sodium bicarbonate Inorganic materials 0.000 claims description 3
- 235000017557 sodium bicarbonate Nutrition 0.000 claims description 3
- 239000003513 alkali Substances 0.000 claims 1
- 239000002585 base Substances 0.000 claims 1
- 230000007246 mechanism Effects 0.000 description 28
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- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 13
- 239000006185 dispersion Substances 0.000 description 13
- CTENFNNZBMHDDG-UHFFFAOYSA-N Dopamine hydrochloride Chemical compound Cl.NCCC1=CC=C(O)C(O)=C1 CTENFNNZBMHDDG-UHFFFAOYSA-N 0.000 description 10
- 229960001149 dopamine hydrochloride Drugs 0.000 description 10
- 230000010287 polarization Effects 0.000 description 10
- 239000000126 substance Substances 0.000 description 10
- 229910052709 silver Inorganic materials 0.000 description 8
- QGUAJWGNOXCYJF-UHFFFAOYSA-N cobalt dinitrate hexahydrate Chemical compound O.O.O.O.O.O.[Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O QGUAJWGNOXCYJF-UHFFFAOYSA-N 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 6
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 6
- PLKATZNSTYDYJW-UHFFFAOYSA-N azane silver Chemical compound N.[Ag] PLKATZNSTYDYJW-UHFFFAOYSA-N 0.000 description 6
- 229910052759 nickel Inorganic materials 0.000 description 6
- 230000009471 action Effects 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
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- 238000006722 reduction reaction Methods 0.000 description 5
- 238000001878 scanning electron micrograph Methods 0.000 description 5
- 239000004332 silver Substances 0.000 description 5
- LENZDBCJOHFCAS-UHFFFAOYSA-N tris Chemical compound OCC(N)(CO)CO LENZDBCJOHFCAS-UHFFFAOYSA-N 0.000 description 5
- 239000011701 zinc Substances 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 229910017052 cobalt Inorganic materials 0.000 description 4
- 239000010941 cobalt Substances 0.000 description 4
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 4
- 238000011065 in-situ storage Methods 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 238000006116 polymerization reaction Methods 0.000 description 4
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- 238000001035 drying Methods 0.000 description 3
- 230000002349 favourable effect Effects 0.000 description 3
- 229910052737 gold Inorganic materials 0.000 description 3
- 238000001338 self-assembly Methods 0.000 description 3
- GGCZERPQGJTIQP-UHFFFAOYSA-N sodium;9,10-dioxoanthracene-2-sulfonic acid Chemical compound [Na+].C1=CC=C2C(=O)C3=CC(S(=O)(=O)O)=CC=C3C(=O)C2=C1 GGCZERPQGJTIQP-UHFFFAOYSA-N 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 230000002195 synergetic effect Effects 0.000 description 3
- 238000001291 vacuum drying Methods 0.000 description 3
- XIOUDVJTOYVRTB-UHFFFAOYSA-N 1-(1-adamantyl)-3-aminothiourea Chemical group C1C(C2)CC3CC2CC1(NC(=S)NN)C3 XIOUDVJTOYVRTB-UHFFFAOYSA-N 0.000 description 2
- 101710134784 Agnoprotein Proteins 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- WTDRDQBEARUVNC-UHFFFAOYSA-N L-Dopa Natural products OC(=O)C(N)CC1=CC=C(O)C(O)=C1 WTDRDQBEARUVNC-UHFFFAOYSA-N 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical group [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- MHUWZNTUIIFHAS-CLFAGFIQSA-N dioleoyl phosphatidic acid Chemical compound CCCCCCCC\C=C/CCCCCCCC(=O)OCC(COP(O)(O)=O)OC(=O)CCCCCCC\C=C/CCCCCCCC MHUWZNTUIIFHAS-CLFAGFIQSA-N 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 238000007772 electroless plating Methods 0.000 description 2
- 125000000524 functional group Chemical group 0.000 description 2
- 238000003837 high-temperature calcination Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- 229960004502 levodopa Drugs 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000005389 magnetism Effects 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- 231100000252 nontoxic Toxicity 0.000 description 2
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- 230000035699 permeability Effects 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 238000006479 redox reaction Methods 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- QKNYBSVHEMOAJP-UHFFFAOYSA-N 2-amino-2-(hydroxymethyl)propane-1,3-diol;hydron;chloride Chemical compound Cl.OCC(N)(CO)CO QKNYBSVHEMOAJP-UHFFFAOYSA-N 0.000 description 1
- SLCITEBLLYNBTQ-UHFFFAOYSA-N CO.CC=1NC=CN1 Chemical compound CO.CC=1NC=CN1 SLCITEBLLYNBTQ-UHFFFAOYSA-N 0.000 description 1
- MYPQMIXEQWTNHO-UHFFFAOYSA-N CO.O.O.O.O.O.O.[N+](=O)([O-])[O-].[Co+2].[N+](=O)([O-])[O-] Chemical compound CO.O.O.O.O.O.O.[N+](=O)([O-])[O-].[Co+2].[N+](=O)([O-])[O-] MYPQMIXEQWTNHO-UHFFFAOYSA-N 0.000 description 1
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- YBCVMFKXIKNREZ-UHFFFAOYSA-N acoh acetic acid Chemical compound CC(O)=O.CC(O)=O YBCVMFKXIKNREZ-UHFFFAOYSA-N 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000007853 buffer solution Substances 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
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- 238000005119 centrifugation Methods 0.000 description 1
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- 229910021389 graphene Inorganic materials 0.000 description 1
- 229910021472 group 8 element Inorganic materials 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000009191 jumping Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000002923 metal particle Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 150000002815 nickel Chemical class 0.000 description 1
- AOPCKOPZYFFEDA-UHFFFAOYSA-N nickel(2+);dinitrate;hexahydrate Chemical compound O.O.O.O.O.O.[Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O AOPCKOPZYFFEDA-UHFFFAOYSA-N 0.000 description 1
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(II) nitrate Inorganic materials [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 238000005325 percolation Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 1
- 238000002310 reflectometry Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 229910001961 silver nitrate Inorganic materials 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K3/00—Materials not provided for elsewhere
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K9/00—Screening of apparatus or components against electric or magnetic fields
- H05K9/0073—Shielding materials
- H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A30/00—Adapting or protecting infrastructure or their operation
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
Abstract
The invention provides a composite shielding material and a preparation method thereof. The preparation method comprises the following steps: reacting a first metal salt with a nitrogen-containing heterocyclic organic ligand in the presence of a first solvent to obtain a metal organic framework compound; the first metal element in the first metal salt is selected from one or more of the element species in group VIII; calcining the metal organic framework compound in an inert atmosphere to obtain a first metal/porous carbon composite material; reacting the first metal/porous carbon composite material with dopamine to obtain first metal/porous carbon@polydopamine; under the condition that the pH value is 8.0-8.5, reacting the first metal/porous carbon@polydopamine with a second metal salt in a second solvent to obtain a composite shielding material; the second metal element in the second metal salt is a metal element having electromagnetic shielding property. The reflection of the composite shielding material on electromagnetic waves can be greatly improved, so that the shielding effectiveness of the composite shielding material is greatly improved.
Description
Technical Field
The invention relates to the technical field of electromagnetic shielding, in particular to a composite shielding material and a preparation method thereof.
Background
Electronic devices radiate high-frequency electromagnetic waves, such as microwaves and radio-frequency electromagnetic waves, at high power and high speed operation, which not only interrupt or hinder the effective operation of neighboring devices, but also pollute the ecological environment and harm the health of living beings. In order to protect natural environments from electromagnetic pollution, equipment from electromagnetic interference, and surrounding organisms from electromagnetic hazards, electromagnetic shielding materials have been developed and become one of effective methods for solving the above problems.
Metal Organic Frameworks (MOFs) have a rich spatial topology. Through modification and modification, the design and improvement of the pore channel structure and the pore size distribution of MOFs can be realized, so that the specific surface area of the MOFs is larger than that of the traditional carbon material, and the specific surface area of the MOFs can reach 6200m 2/g at most. In addition, MOFs have the characteristics of large specific surface area, high porosity, multiple active sites and the like. In the preparation process of the single-metal MOFs or multi-metal MOFs, after the MOFs are subjected to high-temperature calcination treatment, high-permeability metals (such as iron and cobalt) are often embedded into MOFs matrix materials, so that the permeability of MOFs derivative materials is improved. This aspect increases the magnetic losses; on the other hand, the difference between the dielectric constant and the magnetic permeability of MOFs derivative materials is reduced, impedance matching is better realized, and the porous structure formed after high-temperature calcination and an interface polarization mechanism can provide more microwave reflection and scattering effects.
However, in the conventional preparation methods of MOFs and carbonized derivatives thereof, the introduction of carbon-based fillers (such as graphene, carbon nanotubes, carbon fibers, carbon black, etc.) limits the formation of microscopic current networks and electron relaxation polarization behavior (jumping conductance is dominant in MOFs materials, and larger lattice energy is required for charge-skipping interfaces, defects and functional groups) in carbonized derivatives, which leads to poor conductive properties of the materials and thus poor shielding effectiveness.
In view of the above problems, a method for preparing an electromagnetic shielding material, which is commonly used at present, includes: the high conductivity is obtained by introducing conductive particles, and the reflectivity of the material surface to electromagnetic waves is improved by means of impedance mismatch characteristics, so that higher shielding effectiveness is obtained. However, this approach is mostly filled with metal particles, which not only have a high percolation value (mass fraction > 50%) but also have an excessive density. Thus, constructing a highly conductive network structure is not the best solution for designing an ideal EMI shielding material. An excessively high conductivity generally represents a high reflection of electromagnetic waves, which may result in secondary pollution of the electromagnetic waves.
On the basis, in order to improve the conductivity and shielding effectiveness of the electromagnetic shielding material and avoid secondary pollution of electromagnetic waves, the preparation method of the electromagnetic shielding material and the structure of the electromagnetic shielding material need to be reasonably designed in an optimized way.
Disclosure of Invention
The invention mainly aims to provide a composite shielding material and a preparation method thereof, which are used for solving the problem that an electromagnetic shielding material in the prior art is difficult to simultaneously have good conductivity and good shielding effect.
In order to achieve the above object, according to an aspect of the present invention, there is provided a method for preparing a composite shielding material, the method comprising: s1, reacting a first metal salt with a nitrogen-containing heterocyclic organic ligand in the presence of a first solvent to obtain a metal organic framework compound; the first metal element in the first metal salt is selected from one or more of the element species in group VIII; s2, calcining the metal organic framework compound in an inert atmosphere to obtain a first metal/porous carbon composite material; s3, reacting the first metal/porous carbon composite material with dopamine to obtain first metal/porous carbon@polydopamine; s4, under the condition that the pH is 8.0-8.5, enabling the first metal/porous carbon@polydopamine to react with a second metal salt in a second solvent to obtain a first metal/porous carbon@polydopamine@second metal, namely a composite shielding material; the second metal element in the second metal salt is a metal element having electromagnetic shielding property.
Further, the weight ratio of the first metal/porous carbon@polydopamine to the second metal salt is (1-2): 2-5; preferably, the second metal element is selected from Ag and/or Au.
Further, in the step S4, the pH of the reaction system is 8.0-8.5, and the reaction time is 30-60min.
Further, the first metal element is selected from Co and/or Ni; the nitrogen-containing heterocyclic organic ligand is selected from one or more of the group consisting of 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-phenylimidazole.
Further, the mass ratio of the first metal element, the nitrogen-containing heterocyclic organic ligand and the dopamine is (3.44-7.39): 12.18-24.36): 0.53-3.16.
Further, the temperature of the calcination treatment is 700-800 ℃, the temperature rising rate is 1-5 ℃/min, and the time is 5-8 h.
Further, step S3 further includes: adding a buffering agent into the reaction system to adjust the pH; preferably, the buffer is an aqueous solution of a first compound with an acid or a base, wherein the first compound is selected from one or more of the group consisting of tris, potassium dihydrogen phosphate, citric acid and sodium bicarbonate; the acid is selected from one or more of hydrochloric acid, nitric acid and acetic acid, and the base is selected from ammonia water and/or sodium hydroxide.
Further, the reaction time in the step S3 is 6-12 h.
Further, step S4 further includes: reducing the second metal ions in the second metal salt by adding a reducing agent into the reaction system; preferably, the reducing agent is selected from the group of aldehyde group containing organic reducing agents, preferably one or more of the group consisting of glucose, tartaric acid and acetaldehyde; preferably, the first solvent is selected from one or more of the group consisting of methanol, isopropanol and ethanol; the second solvent is selected from distilled water and/or deionized water; more preferably, when the reducing agent is a combination of glucose and tartaric acid, the weight ratio of glucose to tartaric acid is (3-4): 1-2.
In order to achieve the above object, another aspect of the present application further provides a composite shielding material, which is manufactured by the manufacturing method of the composite shielding material provided by the present application, or from inside to outside, and includes a first metal/porous carbon core, a polydopamine coating layer, and a second metal conductive layer in this order, wherein the first metal is selected from one or more of element types in group VIII, and the second metal is selected from Ag and/or Au; preferably, the first metal is selected from Co and/or Ni; preferably, the thickness of the polydopamine coating layer is 10-20 nm, and the thickness of the second metal conductive layer is 20-60 nm.
By applying the technical scheme of the application, the following multiple loss mechanisms are simultaneously introduced into the composite shielding material by adopting the preparation method, wherein the multiple loss mechanisms comprise a magnetic loss mechanism of a first metal element (such as Co and Ni), a dielectric loss mechanism of a second metal element (metal element with electromagnetic shielding performance (such as Ag and Au)), an interface loss mechanism between the first metal and porous carbon, a porous carbon and polydopamine coating layer and between the polydopamine coating layer and a second metal conducting layer, and a dipole polarization loss mechanism. The reflection of the composite shielding material on electromagnetic waves can be greatly improved by utilizing the combined action of the diversified loss mechanisms, so that the shielding effectiveness of the composite shielding material is greatly improved. In addition, compared with the traditional electroless plating method, the preparation method provided by the application is simple, convenient, efficient, nontoxic, pollution-free and low in cost.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:
FIG. 1 shows a scanning electron micrograph (SEM image) of a metal-organic framework compound ZIF-67 prepared in example 1 of the present invention at 10000 times with a scale bar of 1. Mu.m;
FIG. 2 shows a scanning electron micrograph (SEM image) of Co/C@PDA prepared in example 1 of the present invention at 10000 times with a scale bar of 1. Mu.m.
Detailed Description
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The present application will be described in detail with reference to examples.
As described in the background art, the existing electromagnetic shielding material has the problem that it is difficult to have both good conductivity and good shielding effectiveness. In order to solve the technical problems, the application provides a preparation method of a composite shielding material, which comprises the following steps: s1, reacting a first metal salt with a nitrogen-containing heterocyclic organic ligand in the presence of a first solvent to obtain a metal organic framework compound; the first metal element in the first metal salt includes, but is not limited to, one or more of the group VIII element species; s2, calcining the metal organic framework compound in an inert atmosphere to obtain a first metal/porous carbon composite material; s3, reacting the first metal/porous carbon composite material with dopamine to obtain first metal/porous carbon@polydopamine; s4, under the condition that the pH is 8.0-8.5, enabling the first metal/porous carbon@polydopamine to react with a second metal salt in a second solvent to obtain a first metal/porous carbon@polydopamine@second metal, namely a composite shielding material; the second metal element in the second metal salt is a metal element having electromagnetic shielding property.
In the step S1, a first metal salt and a nitrogen-containing heterocyclic organic ligand undergo a coordination reaction and self-assembly to form a metal organic framework compound; in the step S2, the calcining treatment is performed to carbonize the nitrogen-containing heterocyclic organic ligand to form porous carbon, and meanwhile, the first metal element in the metal organic framework compound forms a first metal simple substance under an inert atmosphere, so as to finally form the first metal/porous carbon composite material.
In step S3, the Dopamine (DA) undergoes an oxidative self-polymerization reaction to form Polydopamine (PDA), and the phenolic hydroxyl groups and the nitrogen-containing functional groups (such as amino groups) contained in the polydopamine structure can form a strong physical adsorption effect with the surface of the first metal/porous carbon composite material. Through in-situ polymerization of dopamine and bridging action of polydopamine, a firm polydopamine coating layer is formed on the surface of the first metal/porous carbon composite material.
In step S4, under a specific pH condition, polydopamine is used as a reducing agent to reduce the second metal ions in the second metal salt into a second metal simple substance, and the second metal simple substance generated in this part can also continuously catalyze the oxidation-reduction reaction, so as to continuously generate more second metal simple substance particles, and the second metal simple substance particles are gradually deposited and coated on the surface of the first metal/porous carbon@polydopamine composite material, so as to obtain the composite shielding material. The in-situ synthesis and cladding of the second metal can obtain a second metal conductive layer with higher dielectric constant, thereby improving the conductivity of the composite shielding material.
The preparation method introduces the following multiple loss mechanisms into the composite shielding material, wherein the multiple loss mechanisms comprise a magnetic loss mechanism of a first metal element (such as Co and Ni), a dielectric loss mechanism of a second metal element (metal element with electromagnetic shielding performance such as Ag and Au), an interface loss mechanism between the first metal and porous carbon, a porous carbon and polydopamine coating layer and between the polydopamine coating layer and a second metal conducting layer, and a dipole polarization loss mechanism. The reflection of the composite shielding material on electromagnetic waves can be greatly improved by utilizing the combined action of the diversified loss mechanisms, so that the shielding effectiveness of the composite shielding material is greatly improved. In addition, compared with the traditional electroless plating method, the preparation method provided by the application is simple, convenient, efficient, nontoxic, pollution-free and low in cost.
In a preferred embodiment, the weight ratio of the first metal/porous carbon @ polydopamine to the second metal salt is (1-2): 2-5. The weight ratio of the first metal/porous carbon@polydopamine to the second metal salt comprises but is not limited to the above range, and the weight ratio is limited to the above range, so that the generation rate of the second metal simple substance is improved, and meanwhile, the thickness of the second metal conductive layer is controlled in a proper range, so that the conductivity of the composite shielding material is further improved.
In order to further exert the dielectric loss property of the second metal element, the dielectric loss of the composite shielding material is improved, thereby further improving the shielding effectiveness thereof, preferably the second metal element includes, but is not limited to, ag and/or Au.
In order to further control the reaction rate and the reaction degree of the oxidation-reduction reaction within a proper range, and further make the thickness of the second metal conductive layer within a proper range, it is advantageous to achieve that the conductive performance of the composite shielding material can be improved without increasing the weight of the composite shielding material, and in a preferred embodiment, in the step S4, the pH of the reaction system is 8.0 to 8.5, and the reaction time is 30 to 60 minutes.
In a preferred embodiment, the first metal element includes, but is not limited to, co and/or Ni. The first metal element of the above kind has a certain magnetism, and the use of the first metal element of the above kind is advantageous for further improving the magnetic loss performance. In an alternative embodiment, the nitrogen-containing heterocyclic organic ligands include, but are not limited to, one or more of the group consisting of 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-phenylimidazole. The nitrogen-containing heterocyclic organic ligand and the first metal salt can undergo coordination reaction and self-assembly to form a metal organic framework compound with a specific structure, which is beneficial to improving the shielding effectiveness of the composite shielding material.
In a preferred embodiment, the ratio of the amounts of the first metal element, the nitrogen-containing heterocyclic organic ligand and the dopamine is (3.44-7.39): 12.18-24.36): 0.53-3.16. The mass ratio of the first metal element, the nitrogen-containing heterocyclic organic ligand and the dopamine comprises but is not limited to the above range, and the limitation of the mass ratio in the above range is beneficial to improving the generation rate of the metal organic framework compound with a specific structure on one hand, and improving the coating amount of polydopamine on the surface of the first metal/porous carbon composite material on the other hand, so as to improve the interfacial loss between the porous carbon and polydopamine coating layer and between the polydopamine coating layer and the second metal conductive layer.
In order to carbonize the nitrogen-containing heterocyclic organic ligand in the metal-organic framework compound to form porous carbon with specific porosity, and further introduce polarization loss generated by dipole polarization, and simultaneously, in order to improve the structural stability and the crystal form uniformity of the metal/porous carbon composite material, in a preferred embodiment, the calcination treatment temperature is 700-800 ℃, the heating rate is 1-5 ℃/min, and the time is 5-8 h.
Dopamine (DA) is capable of undergoing oxidative self-polymerization and forming Polydopamine (PDA). In a preferred embodiment, step S3 further comprises: a buffer is added into the reaction system to adjust the pH. The buffer is adopted to adjust the pH of the reaction system in the step S3 to create proper reaction conditions for the reaction, so that the oxidation self-polymerization reaction of the dopamine is more thorough, the generation rate of the polydopamine is improved, and the interface loss of the composite shielding material is further improved.
In an alternative embodiment, the buffer is an aqueous solution of a first compound with an acid or base, wherein the first compound includes, but is not limited to, one or more of the group consisting of tris, potassium dihydrogen phosphate, citric acid, and sodium bicarbonate; the acid includes, but is not limited to, one or more of the group consisting of hydrochloric acid, nitric acid, and acetic acid (acetic acid), and the base includes, but is not limited to, ammonia and/or sodium hydroxide. Compared with other types of buffering agents, the buffer agents can further improve the generation rate of polydopamine and further improve the interface loss of the composite shielding material.
In a preferred embodiment, the reaction time of step S3 is from 6 to 12 hours. The reaction time in the step S3 includes, but is not limited to, the above-mentioned range is limited to be favorable for making the reaction more thorough, and making the polydopamine coating layer formed by cladding the polydopamine generated by the reaction stronger, so that the interface loss of the polydopamine coating layer can be further developed, and the subsequent cladding treatment of the second metal conductive layer can be facilitated.
In a preferred embodiment, step S4 further comprises: and adding a reducing agent into the reaction system to reduce second metal ions in the second metal salt. The reaction efficiency of reducing the second metal ion into the second metal simple substance is improved under the synergistic reduction effect of polydopamine and a reducing agent (such as glucose, tartaric acid and the like).
In order to further increase the reaction efficiency of the reduction of the second metal ion to the second metal simple substance, preferably, the reducing agent includes, but is not limited to, an organic-based reducing agent containing an aldehyde group. Compared with an inorganic reducing agent, the organic reducing agent can be used for combining the second metal salt with the organic reducing agent and then adsorbing the second metal salt on the surface of the first metal/porous carbon@polydopamine, so that the in-situ synthesis and coating of the second metal are facilitated. In an alternative embodiment, the reducing agent includes, but is not limited to, one or more of the group consisting of glucose, tartaric acid, and acetaldehyde. More preferably, when the reducing agent is a combination of glucose and tartaric acid, the weight ratio of glucose to tartaric acid is (3-4): 1-2.
In a preferred embodiment, the first solvent includes, but is not limited to, one or more of the group consisting of methanol, ethanol, and propanol. Compared with other types of solvents, the first solvent of the type is favorable for improving the dispersion uniformity of the first metal salt and the nitrogen-containing heterocyclic organic ligand, and further improving the reaction degree of coordination reaction and self-assembly of the first metal salt and the nitrogen-containing heterocyclic organic ligand.
In a preferred embodiment, the second solvent includes, but is not limited to distilled and/or deionized water. Compared with other types of solvents, the second solvent of the type is favorable for improving the dispersion uniformity of the first metal/porous carbon@polydopamine and the second metal salt, further improving the thickness uniformity of a second metal simple substance layer generated in situ by the second metal salt, and inhibiting the condition of unstable shielding performance caused by nonuniform coating thickness of the second metal conductive layer.
The second aspect of the present application also provides a composite shielding material, which is prepared by the preparation method of the composite shielding material provided by the present application, or from inside to outside, and sequentially comprises a first metal/porous carbon core, a polydopamine coating layer and a second metal conductive layer, wherein the first metal comprises one or more of element types in group VIII, but not limited to Ag and/or Au.
The composite shielding material is simultaneously introduced with the following multiple loss mechanisms, including a magnetic loss mechanism of a first metal element (such as Co and Ni), a dielectric loss mechanism of a second metal element (such as Ag and Au), an interface loss mechanism between the first metal and porous carbon, a porous carbon and polydopamine coating layer and a second metal conductive layer, and a dipole polarization loss mechanism. The reflection of the composite shielding material on electromagnetic waves can be greatly improved by utilizing the combined action of the diversified loss mechanisms, so that the shielding effectiveness of the composite shielding material is greatly improved.
In a preferred embodiment, the first metal includes, but is not limited to, co and/or Ni. The first metal element of the above kind has a certain magnetism, and the use of the first metal element of the above kind is advantageous for further improving the magnetic loss performance.
In a preferred embodiment, the thickness of the polydopamine coating is 10 to 20nm and the thickness of the second metallic conductive layer is 20 to 60nm. The thickness of the polydopamine coating layer includes, but is not limited to, the above range, and the limitation of the thickness in the above range is beneficial to improving the conductivity of the composite shielding material without increasing the weight of the composite shielding material, and simultaneously inhibiting secondary pollution of electromagnetic waves.
The electromagnetic shielding performance of the composite shielding materials prepared in all examples and comparative examples in the present application was evaluated by the following test methods.
The composite shielding materials prepared in all examples and comparative examples of the present application were mixed with paraffin wax at a weight ratio of 3:1 to prepare a coaxial ring having an inner diameter of 3.0mm, an outer diameter of 7.0mm and a thickness of 2.0 mm. Electromagnetic parameters and S parameters of the composite shielding material are tested by using a vector network analyzer E5071C, and shielding effectiveness of the composite shielding material in the 8.2-12.4 GHz frequency band is calculated, wherein the test standard is GB/T32596-2016.
Wherein, the index of the good or bad electromagnetic shielding material performance is called the shielding effectiveness of the composite shielding material. The total shielding effectiveness (SE T) of the composite shielding material includes the reflection loss at the surface of the shielding (SE R), the absorption loss at the shielding (SE A), and the multiple reflection loss at the interior of the shielding (SE MR).
The application is described in further detail below in connection with specific examples which are not to be construed as limiting the scope of the application as claimed.
Example 1
A method of preparing a composite shielding material, comprising:
s1, weighing 1g of cobalt nitrate hexahydrate Co (NO 3)2·6H2 O is dissolved in 100ml of methanol, weighing 1g of 2-methylimidazole and adding into 100ml of methanol, and obtaining a 2-methylimidazole dispersion after complete dissolution, pouring the 2-methylimidazole methanol dispersion into the cobalt nitrate hexahydrate methanol dispersion, magnetically stirring for 24 hours at room temperature, centrifugally washing by methanol, collecting a product, and finally drying in a vacuum drying oven at 60 ℃ for 18 hours to obtain a metal organic framework compound ZIF-67, wherein the microscopic morphology of the ZIF-67 is polyhedral particles with smooth surfaces as shown in figure 1.
And S2, calcining the metal organic framework compound sample in a nitrogen atmosphere, wherein the heating rate is 2 ℃/min, and continuously calcining for 6 hours at the calcining temperature of 700 ℃ to obtain the Co/C composite material sample.
S3, dissolving 0.5g of Tris (hydroxymethyl) aminomethane (Tris) in 500mL of distilled water, regulating the pH of a reaction system to 8.0 by using 1.0mol/L HCl, adding 1g of Co/C or Ni/C sample into Tris-HCl buffer solution, stirring for 45min, adding 0.3g of dopamine hydrochloride (DOPA. HCl) into the solution, stirring for about 8h, washing the sample by using deionized water, and vacuum drying at 60 ℃ to obtain Co/C@PDA. The mass ratio of cobalt nitrate hexahydrate, 2-methylimidazole and dopamine hydrochloride (or dopamine) is 3.44:12.18:1.58. As can be seen from the SEM image shown in FIG. 2, the surface roughness of the prepared Co/C@PDA indicates that the coated sample with dopamine was successfully prepared as compared with FIG. 1.
S4, slowly dropwise adding ammonia water into a silver nitrate (AgNO 3) solution by using a dropper, changing the solution from transparent to turbid, continuously dropwise adding the ammonia water until the solution is just clarified, obtaining 10g/L silver ammonia solution, adding 1g of Co/C@PDA sample into the 500mL 10g/L silver ammonia solution (the weight ratio of the first metal/porous carbon@polydopamine to the second metal salt is 1:5), dissolving glucose and tartaric acid with the weight ratio of 3:1 into the reaction solution, reacting for 45min at normal temperature (25 ℃), and drying the product at room temperature to obtain Co/C@PDA@Ag.
Example 2
The difference from example 1 is that: the first metal salt was nickel nitrate hexahydrate Ni (NO 3)2·6H2O,Ni(NO3)2·6H2 O, 2-methylimidazole to dopamine hydrochloride (or dopamine) in a mass ratio of 3.67:12.18:1.58.
Example 3
The difference from example 1 is that: in the step S4, 2g of Co/C@PDA sample is added into 200mL of 10g/L silver ammonia solution, namely the weight ratio of the first metal/porous carbon@polydopamine to the second metal salt is 1:1.
Example 4
The difference from example 1 is that: in step S4, 4g of the Co/C@PDA sample was added to 200mL of a 10g/L silver ammonia solution at a ratio of 2:1.
Example 5
The difference from example 1 is that: in step S4, the reaction time was 30min.
Example 6
The difference from example 1 is that: the pH of the reaction system in the step S4 was 8.5, and the reaction time was 60min.
Example 7
The difference from example 1 is that: in step S4, the reaction time was 120min.
Example 8
The difference from example 1 is that: the weight ratio of the weighed cobalt nitrate hexahydrate, 2-methylimidazole and dopamine hydrochloride is 1:1:0.1, namely Co (the mass ratio of NO 3)2·6H2 O, 2-methylimidazole and dopamine is 3.44:12.18:0.53).
Example 9
The difference from example 1 is that: the weight ratio of the weighed cobalt nitrate hexahydrate, 2-methylimidazole and dopamine hydrochloride is 2:2:0.6, namely Co (the mass ratio of NO 3)2·6H2 O, 2-methylimidazole and dopamine is 6.87:24.36:3.16).
Example 10
The difference from example 1 is that: the weight ratio of the weighed cobalt nitrate hexahydrate, 2-methylimidazole and dopamine hydrochloride is 1:0.5:0.6, namely Co (the mass ratio of NO 3)2·6H2 O, 2-methylimidazole and dopamine is 3.44:6.09:3.16).
Example 11
The difference from example 1 is that: in the step S1, cobalt nitrate hexahydrate Co (the dosage of NO 3)2·6H2 O is 2g, the dosage of 2-methylimidazole is 2g, the dosage of methanol in the cobalt nitrate hexahydrate dispersion liquid and the 2-methylimidazole dispersion liquid is 200mL respectively, the dosage of Tris in the step S3 is 1g, and the dosage of dopamine hydrochloride is 0.6g, namely the mass ratio of cobalt element, 2-methylimidazole and dopamine hydrochloride (or dopamine) is 6.87:24.36:3.16.
Example 12
The difference from example 1 is that: in step S1, 1g of Co (NO 3)2·6H2 O and 1g of Ni (NO 3)2·6H2 O are dissolved in 100ml of methanol; the amount of 2-methylimidazole is 1.5g (18.27 mmol)), namely cobalt salt and nickel salt, and the mass ratio of 2-methylimidazole to dopamine hydrochloride (or dopamine) is 7.13:18.27:1.58, respectively.
Example 13
The difference from example 1 is that: in step S2, the calcination treatment time was 8 hours.
Example 14
The difference from example 1 is that: in step S2, the calcination treatment is carried out at 800 ℃ for 5 hours.
Example 15
The difference from example 1 is that: in step S2, the calcination treatment was carried out at 500℃for 3 hours.
Example 16
The difference from example 1 is that: in step S2, the temperature rising rate of the calcination treatment is 8 ℃/min.
Example 17
The difference from example 1 is that: in step S4, no reducing agent (glucose and tartaric acid) is added.
Comparative example 1
The difference from example 1 is that: 1g of Co (NO 3)2·6H2 O was dissolved in 200ml of methanol to obtain a cobalt salt dispersion, 1.0g of 2-methylimidazole was dissolved in 200ml of methanol to obtain a 2-methylimidazole dispersion after sufficient dissolution, and the 2-methylimidazole dispersion was poured into the cobalt salt dispersion to obtain a solution A.
0.5G of Tris (hydroxymethyl) aminomethane (Tris) was dissolved in 500mL of distilled water, the pH was adjusted to 7.0 with 1.0mol/L HCl, and stirred for 30min, and 0.3g of DOPA HCl was added to the above solution and stirred for about 8 hours, to give solution B.
Slowly dropwise adding ammonia water into the AgNO 3 solution by using a dropper, changing the solution from transparent to turbid, continuously dropwise adding the ammonia water until the solution is just clarified, obtaining 10g/L silver ammonia solution, and dissolving glucose and tartaric acid with the weight ratio of 3:1 into the 500mL, 10g/L silver ammonia solution to obtain solution C.
The above-prepared solution A, solution B and solution C were mixed and stirred at room temperature for 24 hours, and the product was collected by centrifugation through methanol. Finally, drying for 12 hours in a vacuum drying oven at 70 ℃ to obtain the ZIFs/PDA/Ag composite material.
And (3) calcining the ZIFs/PDA/Ag sample in a nitrogen atmosphere, wherein the heating rate is 2 ℃/min, and the calcination is continuously performed for 5 hours at the calcination temperature of 700 ℃ to finally obtain the Co/C/Ag composite material.
Comparative example 2
The difference from example 1 is that: the first metal salt is zinc nitrate hexahydrate Zn (NO 3)2·6H2 O, namely the first metal element is zinc element, and the mass ratio of Zn element, 2-methylimidazole and dopamine hydrochloride (or dopamine) is 3.36:12.18:1.58. The comparative example finally prepares a Zn/C@PDA@Ag nonmagnetic sample.
TABLE 1
SE T for composite Shielding Material (dB) | |
Example 1 | 57.7 |
Example 2 | 50.5 |
Example 3 | 57.9 |
Example 4 | 52.2 |
Example 5 | 55.0 |
Example 6 | 55.9 |
Example 7 | 39.2 |
Example 8 | 57.2 |
Example 9 | 56.8 |
Example 10 | 42.0 |
Example 11 | 54.0 |
Example 12 | 62.0 |
Example 13 | 57.8 |
Example 14 | 58.2 |
Example 15 | 49.5 |
Example 16 | 56.7 |
Example 17 | 50.2 |
Comparative example 1 | 41.7 |
Comparative example 2 | 43.5 |
From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:
In comparative example 1, a first metal salt, a nitrogen-containing heterocyclic organic ligand, dopamine and a second metal salt were prepared into respective dispersions, the dispersions were directly mixed, and finally, calcination was directly performed to obtain a product Co/C/Ag composite. In comparison with example 1, the preparation method in comparative example 1 cannot obtain the polydopamine coating layer because it is carbonized to form porous carbon during the calcination treatment; meanwhile, since the reduced product silver particles are incorporated into the ZIFs/C or ZIFs/PDA structures during the calcination process, a complete metallic silver conductive layer cannot be formed, and thus the composite shielding material obtained in comparative example 1 is completely different from that obtained in example 1. As can be seen from comparison of the results of the shielding performance test in Table 1, the Co/C@PDA@Ag composite shielding material prepared in example 1 of the present application has a shielding performance (57.7 dB) significantly better than that of the Co/C/Ag composite material of comparative example 1 (46.8 dB). This shows that the following multiple loss mechanisms are introduced into the composite shielding material provided by the application, including a magnetic loss mechanism of a first metal element (such as Co), a dielectric loss mechanism of a second metal element (such as Ag) per se, an interface loss mechanism between the first metal and porous carbon, a porous carbon and polydopamine coating layer, an interface loss mechanism between the polydopamine coating layer and a second metal conductive layer, and a loss mechanism caused by dipole polarization. The reflection of the composite shielding material on electromagnetic waves can be greatly improved by utilizing the combined action of the diversified loss mechanisms, so that the shielding effectiveness of the composite shielding material is greatly improved.
The first metal element in example 1 is cobalt, and the first metal element in example 2 is nickel, both of which are elements in group VIII; whereas the first metal salt in comparative example 2 was zinc nitrate hexahydrate, i.e., the first metal element was zinc element of group IIB. From the test results in Table 1, the shielding effectiveness (57.7 dB) of example 1 is significantly better than 49.7dB of comparative example 2. This shows that the introduction of the element species in group VIII can improve the magnetic loss properties of the composite shielding material based on the reason of the magnetic properties of the first metal element itself, thereby improving the shielding effectiveness of the composite shielding material.
Comparing examples 1,3 and 4, it is seen that the shielding effectiveness of example 1 (57.7 dB) and example 3 (57.9 dB) is superior to example 4 in combination with the shielding effectiveness test results in table 1, which indicates that the shielding effectiveness obtained is superior when the weight ratio of Co/c@pda to silver salt takes a value within the preferred range of the present application. It is known that the weight ratio of the Co/C@PDA to the silver salt includes but is not limited to the preferred range of the application, and the weight ratio is limited to the preferred range of the application, so that the production rate of the second elemental silver metal is improved, and the thickness of the metallic silver conductive layer is controlled in a proper range, so that the conductivity of the composite shielding material is further improved.
Comparing examples 1, 5 to 7, the reaction time in step S4 of example 7 was too long, 120min, and the shielding effectiveness was only 39.2dB, which was significantly lower than 55.0dB in example 5. This means that the pH and the reaction time of the reaction system in step S4 include, but are not limited to, the preferred ranges of the present application, and that limiting the pH and the reaction time to the preferred ranges of the present application is advantageous in that the thickness of the second metal conductive layer is in a suitable range, and in that the conductive performance of the composite shielding material can be improved without increasing the weight of the composite shielding material.
Comparing examples 1, 8 to 12, the amount of 2-methylimidazole used in example 10 is significantly smaller than that in examples 1, 8 and 9, and the shielding effectiveness test results in Table 1 show that example 10 achieves only 42.0dB, which is significantly lower than that in examples 1, 8 and 9. The first metal element in the first metal salt used in example 11 is the preferred species of the present application (cobalt element and nickel element), and the use amount ratio is also within the preferred range of the present application, and the shielding effectiveness is good, which can reach 54.0dB. It is understood that the mass ratio of the first metal element, the 2-methylimidazole and the dopamine includes, but is not limited to, the preferred range of the present application, and the porous carbon and the polydopamine coating layer and the interface loss between the polydopamine coating layer and the second metal conductive layer are improved by limiting the mass ratio to the preferred range of the present application.
Comparing examples 1, 13 to 15, the calcination treatment temperature in example 15 was lower than the preferred range of the present application, and the time was also shorter than the preferred range of the present application, and it was found that the shielding effectiveness in example 15 was only 49.5dB, which is significantly lower than that in examples 13 (57.8 dB) and 14 (58.2 dB) in combination with the data in Table 1. It is understood that, compared with other ranges, the temperature and time of the calcination treatment are limited within the preferred ranges of the present application, which is advantageous for introducing the polarization loss generated by dipole polarization, thereby improving the shielding effectiveness of the composite shielding material.
Comparing examples 1 and 16, it is understood that limiting the rate of temperature rise of the calcination treatment to the preferred range of the present application is advantageous in improving the structural stability and the crystal form uniformity of the Co/C composite material, and thus the shielding effectiveness of the composite shielding material, compared to other ranges.
As is clear from comparing examples 1 and 17, in example 17, the reduction agent was not added additionally, and in the reaction of step S4 in this example, only polydopamine actually had a reduction effect, and it was impossible to reduce all of the silver in the silver salt to elemental silver. The polydopamine in example 1 and the reducing agent (such as glucose, tartaric acid, etc.) have synergistic effect, and the reaction efficiency of reducing the second metal ion into the second metal simple substance is improved under the synergistic reduction effect.
It should be noted that the terms "first," "second," and the like in the description and in the claims are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those described herein.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (13)
1. The preparation method of the composite shielding material is characterized by comprising the following steps of:
Step S1, reacting a first metal salt with a nitrogen-containing heterocyclic organic ligand in the presence of a first solvent to obtain a metal organic framework compound; the first metal element in the first metal salt is selected from Co and/or Ni; wherein the nitrogen-containing heterocyclic organic ligand is selected from one or more of the group consisting of 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-phenylimidazole;
Step S2, calcining the metal-organic framework compound in an inert atmosphere to obtain a first metal/porous carbon composite material;
step S3, reacting the first metal/porous carbon composite material with dopamine to obtain first metal/porous carbon@polydopamine;
Step S4, under the condition that the pH value is 8.0-8.5, enabling the first metal/porous carbon@polydopamine and the second metal salt to react in a second solvent to obtain a first metal/porous carbon@polydopamine@second metal, namely the composite shielding material; the second metal element in the second metal salt is a metal element with electromagnetic shielding performance; in the step S4, the reaction time is 30-60 min;
The mass ratio of the first metal element, the nitrogen-containing heterocyclic organic ligand and the dopamine is (3.44-7.39): 12.18-24.36): 0.53-3.16.
2. The method of producing a composite shielding material according to claim 1, wherein the weight ratio of the first metal/porous carbon @ polydopamine to the second metal salt is (1-2): (2-5).
3. The method of producing a composite shielding material according to claim 2, wherein the second metal element is selected from Ag and/or Au.
4. The method for preparing a composite shielding material according to claim 1, wherein the calcination treatment is performed at a temperature of 700-800 ℃, a heating rate of 1-5 ℃/min, and a time of 5-8 hours.
5. The method for preparing a composite shielding material according to claim 1, wherein the step S3 further comprises:
adding a buffering agent into the reaction system to adjust the pH;
The buffer is an aqueous solution formed by a first compound and acid or alkali, wherein the first compound is one or more selected from the group consisting of tris, potassium dihydrogen phosphate, citric acid and sodium bicarbonate; the acid is selected from one or more of the group consisting of hydrochloric acid, nitric acid and acetic acid, and the base is selected from ammonia water and/or sodium hydroxide.
6. The method for preparing a composite shielding material according to claim 1, wherein the reaction time of the step S3 is 6 to 12 hours.
7. The method for preparing a composite shielding material according to claim 6, wherein the step S4 further comprises:
And adding a reducing agent into the reaction system to reduce second metal ions in the second metal salt.
8. The method for producing a composite shielding material according to claim 7, wherein the reducing agent is selected from aldehyde group-containing organic reducing agents.
9. The method of producing a composite shielding material according to claim 7, wherein the first solvent is one or more selected from the group consisting of methanol, isopropanol, and ethanol; the second solvent is selected from distilled water and/or deionized water.
10. The method of preparing a composite shielding material according to claim 8, wherein the reducing agent is one or more selected from the group consisting of glucose, tartaric acid and acetaldehyde.
11. The method of producing a composite shielding material according to claim 10, wherein the reducing agent is a combination of the glucose and the tartaric acid, and the weight ratio of the glucose to the tartaric acid is (3-4): (1-2).
12. A composite shielding material, characterized in that it is produced by the method for producing a composite shielding material according to any one of claims 1 to 11.
13. The composite shielding material of claim 12, wherein the polydopamine coating layer has a thickness of 10-20 nm and the second metal conductive layer has a thickness of 20-60 nm.
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