Magnetic control chain-shaped polyaniline-based broadband bionic wave-absorbing material and preparation method thereof

Abstract

The invention discloses a magnetic control chained polyaniline-based broadband bionic wave-absorbing material and a preparation method thereof, and relates to the technical field of electromagnetic wave absorbing materials and space functional composites.The magnetic control chained polyaniline-based broadband bionic wave-absorbing material achieves multi-band impedance matching through the cooperation of orientation arrangement of magnetic nano chains and the polarization effect of a polyaniline interface, is extremely low in average reflection loss at 8-18 GHz under the thickness of 1.5 mm, and can be applied to the field of electromagnetic wave absorbing materials and space functional composites. The composite material covers an X-Ku wave band, the material density is less than or equal to 1.6 g / cm < 3 >, the mechanical strength is high, the composite material can be directly compounded on a flexible film antenna substrate, the satellite load mass is saved by more than or equal to 40%, and the wave absorbing performance attenuation is less than or equal to 5% after 100 times of alternating circulation from-180 DEG C (liquid nitrogen) to + 120 DEG C (vacuum), which is superior to that of a traditional carbon-based material (the attenuation is more than or equal to 20%); magnetic field induction and chemical synthesis are combined, the process temperature is smaller than or equal to 250 DEG C, and a flexible processing production line of an existing satellite film antenna is compatible.

Description

Technical Field

[0001] The present invention relates to the technical fields of electromagnetic wave absorption materials and space functional composite materials, and particularly relates to a magnetically controlled chain-like polyaniline-based broadband bionic wave-absorbing material and a preparation method thereof. Background Art

[0002] With the rapid development of low-earth orbit satellite constellations and thin-film antenna technologies, satellite platforms urgently need to achieve multi-band communication compatibility and electromagnetic stealth functions under limited payloads. Currently, thin-film antenna wave-absorbing materials generally use ferrite coatings, carbon-based composite materials, or metal microstructure metasurfaces. However, these materials have significant limitations: ferrite materials have too high a density, resulting in a significant deterioration of the satellite payload ratio; although carbon-based composite materials are lightweight, their dominant dielectric loss mechanism causes the reflection loss to drop sharply in the high-frequency band, making it difficult to meet the stringent requirements of electromagnetic compatibility (EMC) for communication equipment in the Ku band (12 - 18 GHz); although artificial structures such as metal metasurfaces can regulate electromagnetic responses, there is an inherent conflict between their rigid substrates and the flexible folding requirements of thin-film antennas. These contradictions are more prominent in the design of high-payload ratio satellites - as the antenna thickness is limited to sub-millimeter levels (≤2 mm), the thickness-performance contradiction of traditional wave-absorbing materials has become a technical bottleneck.

[0003] Polyaniline (PANI), as a lightweight (density ≈ 1.2 g / cm³) dielectric wave-absorbing material, has adjustable conductivity and electromagnetic loss mechanisms, and theoretically can replace traditional magnetic materials through structural design. However, existing polyaniline-based wave-absorbing materials still face two core challenges: one is the magnetic-impedance mismatch, and the single dielectric loss mechanism of pure polyaniline is difficult to match the free-space impedance within a wide frequency band, resulting in a large amount of electromagnetic waves being reflected and dissipated on the surface; the other is the high-frequency absorption bottleneck. Conventional disordered magnetic particles (such as ) are prone to weakening high-frequency magnetic losses due to the eddy current effect, and particle aggregation will significantly reduce the mechanical uniformity and space environmental stability of the material.

[0004] In nature, magnetotactic bacteria provide cross-scale bionic inspiration for the above problems. The magnetosome chains in their bodies are formed by uniformly sized nanoparticles (20 - 50 nm) arranged along the magnetic field direction, and achieve efficient magnetic energy collection and biological navigation through the magnetic anisotropy and quantum confinement effects of the chain-like structure. This biomineralization mechanism has three characteristics that can be borrowed: one is that the chain-like arrangement of particles avoids aggregation and retains a high specific surface area and single-domain magnetic response; the second is that the precise regulation of the spacing between nanoparticles within the chain can suppress eddy current losses and enhance high-frequency magnetic resonance; the third is that the dielectric-magnetic heterointerfaces formed between the chains can induce local electric field distortion and promote polarization decoupling.

[0005] In the prior art, Patent CN117343321A discloses polyaniline and Mechanically blended particulate microwave absorbing materials, but they do not control the orientation of magnetic particles, resulting in insufficient magnetic loss in the low-frequency band and significant high-frequency eddy current effects; CN115155531B uses an in-situ chemical method to synthesize polyaniline-coated core-shell structures, although improving the interfacial bonding strength, still cannot solve the problem of low magneto-electric synergy efficiency caused by random particle dispersion; Patent CN117822326A prepares fibrous polyaniline microwave absorbers by electrospinning, but the magnetic particles inside the fibers are in a disordered state and cannot utilize geometric anisotropy to enhance magneto-electric coupling. It can be seen that the existing technologies have not achieved the biomimetic chain-like ordered assembly and multi-scale structure regulation of magnetic units, resulting in the microwave absorption performance and lightweight level of polyaniline-based composites being difficult to adapt to the extreme working conditions of high payload ratio satellites.

[0006] Based on the biomimetic design of magnetotactic bacteria magnetosome chains, the present invention proposes a magnetically controlled chain-like polyaniline-based broadband microwave absorbing material. Through magnetic field induction nanoparticles are oriented and arranged into a chain-like structure along a preset direction in the polyaniline matrix, and in-situ chemical synthesis technology is combined to achieve precise coating and doping of the magnetic chains by polyaniline. Finally, a lightweight broadband microwave absorption system with dielectric loss, magnetic resonance loss, and multiple scattering mechanisms is constructed, providing an innovative solution for the electromagnetic stealth of thin-film antennas and the optimization of satellite payload ratio. Summary of the Invention

[0007] The present invention provides a magnetically controlled chain-like polyaniline-based broadband biomimetic microwave absorbing material and its preparation method. By simulating the directional arrangement and magneto-electric synergy mechanism of magnetotactic bacteria magnetosome chains and adopting a magnetic field-induced in-situ chemical synthesis strategy, the problems of magneto-resistance mismatch, insufficient high-frequency absorption ability, and poor mechanical stability of existing polyaniline-based microwave absorbing materials are solved. This material has the characteristics of lightweight, broadband absorption, and high payload ratio adaptability, and is suitable for the electromagnetic stealth and structural integration of satellite thin-film antennas.

[0008] A magnetically controlled chain-like polyaniline-based broadband biomimetic microwave absorbing material, comprising: Polyaniline matrix: accounting for 70%-85%, with conductive polyaniline (Emeraldine salt) as the main body; Magnetic nanochains: chain-like structures formed by the directional arrangement of magnetic nanoparticles of iron oxide nanoparticles under magnetic field induction, accounting for 10%-25%, with a particle size of 20-50 nm; Coupling dopant: a complex system of dioctyl phthalate DOP and sodium dodecylbenzenesulfonate SDBS, accounting for 1%-3%; Flexible substrate adaptation layer: polyimide film PI or aramid fiber-reinforced epoxy resin-based film, with a thickness of 0.1-1.5 mm; Coupled dopants are used to regulate the interfacial bonding of polyaniline-magnetic chains and dielectric loss performance; the flexible substrate adaptation layer serves as the mechanical support of the composite material and the interfacial compatible carrier of the satellite thin-film antenna; The single-chain length of the magnetic nanochains is 2-10 μm, the chain spacing is 50-150 nm, and the inter-particle spacing within the chain is 5-15 nm to suppress high-frequency eddy current losses; Preferably, the degree of orientation of the magnetic nanochains in the polyaniline matrix is ≥80%, and the chain direction is perpendicular to the substrate plane to achieve multi-stage resonance of electromagnetic waves along the chain length direction; Preferably, the polyaniline matrix is in-situ coated on the surface of the nanochains to form a "coral-like" coating structure with a thickness of 10-30 nm to ensure atomic-level contact between the magnetic and electrical components; Preferably, the overall density of the bionic microwave absorbing material is ≤1.6 g / cm³, the reflection loss is ≤ -25 dB in the range of 8-18 GHz, and the effective absorption bandwidth is ≥8 GHz when the thickness is ≤2 mm; The bionic microwave absorbing material has a high effective absorption bandwidth; Preferably, the mass ratio of DOP to SDBS in the coupled dopant is 2:1, and it is in-situ bonded to the surface of the magnetic nanochains during the polyaniline polymerization stage.

[0009] A preparation method of a magnetically controlled chain-like polyaniline-based broadband bionic microwave absorbing material, comprising the following steps: Step 1: In-situ magnetic control assembly of nanochains: Dispersing nanoparticles in an aqueous solution containing polyvinylpyrrolidone PVP, and self-assembling them into a chain-like structure under a perpendicular magnetic field of 0.5-1.5 T; Step 2: In-situ chemical synthesis and coating of polyaniline: Using the nanochains as a template, initiating the polymerization of aniline monomers by an oxidant under the condition of 0-5°C under a parallel magnetic field; Step 3: Material forming and performance optimization: Mixing and coating the composite powder with a polyimide precursor, and stepwise curing to form a microwave absorbing film.

[0010] In the step 1, the perpendicular magnetic field strength is 1.0 T, the reaction temperature is 60-80°C, the reaction time is 1-3 h, and after self-assembly is completed, it is frozen and cured by liquid nitrogen and vacuum dried; In the step 2 is in a molar ratio of 1:15-1:25 to aniline, the molar ratio of the oxidant ammonium persulfate to aniline is 1:1, and a parallel magnetic field of 0.5 T is applied throughout the process; The curing process in the step 3 includes: pre-curing at 80°C for 1 h; thermal imidization at 180°C for 2 h; annealing at 250°C for 20 min; During the curing process, the mass ratio of the composite powder to the polyimide precursor is 1:2 - 1:4, and the coating thickness is 0.5 - 2.0 mm.

[0011] Advantages of the present invention: Through the synergy of the orientation arrangement of magnetic nanochains and the interfacial polarization effect of polyaniline, multi-band impedance matching is achieved. At a thickness of 1.5 mm, the average reflection loss in the 8 - 18 GHz band is extremely low, covering the X - Ku band. The material density ≤ 1.6 g / cm³, with high mechanical strength, can be directly compounded on the flexible thin-film antenna substrate, saving the satellite payload mass ≥ 40%. After 100 cycles of alternating between -180 °C (liquid nitrogen) and +120 °C (vacuum), the wave absorption performance attenuation ≤ 5%, which is superior to traditional carbon-based materials (attenuation ≥ 20%); Combining magnetic field induction and chemical synthesis, the process temperature ≤ 250 °C, compatible with the flexible processing production line of existing satellite thin-film antennas. Description of the drawings

[0012] Figure 1 For Schematic diagram of in-situ growth of polyaniline. Detailed implementation manners

[0013] Please refer to Figure 1 As shown, a magnetically controlled chain-like polyaniline-based broadband bionic wave-absorbing material includes: Polyaniline matrix: accounting for 70% - 85%, with conductive polyaniline (Emeraldine salt) as the main body; Magnetic nanochains: formed by the chain-like structure of Fe₃O₄ nanoparticles oriented by magnetic field induction, accounting for 10% - 25%, with a particle size of 20 - 50 nm; Coupling dopant: a complex system of dioctyl phthalate DOP and sodium dodecylbenzenesulfonate SDBS, accounting for 1% - 3%; Flexible substrate adapter layer: polyimide film PI or aramid fiber-reinforced epoxy resin-based film, with a thickness of 0.1 - 1.5 mm; The coupling dopant is used to regulate the interfacial bonding and dielectric loss performance between polyaniline and magnetic chains; the flexible substrate adapter layer serves as the mechanical support of the composite material and the interfacial compatible carrier of the satellite thin-film antenna; The single-chain length of the magnetic nanochains is 2 - 10 μm, the chain spacing is 50 - 150 nm, and the particle spacing within the chain is 5 - 15 nm to suppress high-frequency eddy current loss; Preferably, the degree of orientation of the magnetic nanochains in the polyaniline matrix ≥ 80%, and the chain direction is perpendicular to the substrate plane to achieve multi-stage resonance of electromagnetic waves along the chain length direction; Preferably, the polyaniline matrix is in-situ coated on On the surface of the nanochains, a "coral-like" coating structure with a thickness of 10 - 30 nm is formed to ensure atomic-level contact between the magnetic and electrical components; Preferably, the overall density of the bionic microwave absorbing material is ≤ 1.6 g / cm³, the reflection loss is ≤ -25 dB in the range of 8 - 18 GHz, and the effective absorption bandwidth is ≥ 8 GHz when the thickness is ≤ 2 mm; The bionic microwave absorbing material has a high effective absorption bandwidth; Preferably, the mass ratio of DOP to SDBS in the coupling dopant is 2:1, and it is in-situ bonded to the surface of the magnetic nanochains during the polyaniline polymerization stage.

[0014] A preparation method of a magnetically controlled chain-like polyaniline-based broadband bionic microwave absorbing material, comprising the following steps: Step 1: In-situ magnetic control assembly of nanochains: Disperse the nanoparticles in an aqueous solution containing 1% polyvinylpyrrolidone (PVP), and ultrasonically treat for 30 min to form a homogeneous suspension (mass concentration 5% - 10%). Inject the mixture into a magnetic field reactor, vertically apply a static magnetic field of 0.5 - 1.5 T, heat to 60 - 80 °C and keep it constant for 1 - 3 h to induce the particles to be arranged in an orderly manner along the magnetic field direction and self-assembled into a chain-like structure. After freeze-drying, obtain nanoparticle chain preforms.

[0015] Step 2: In-situ chemical synthesis and coating of polyaniline: Disperse the 4 nanoparticle chain preforms in a 1M HCl solution, and successively add aniline monomer (molar ratio: aniline = 1:15 - 1:25), dioctyl phthalate DOP and sodium dodecylbenzenesulfonate SDBS, ultrasonically premix for 20 min, then dropwise add ammonium persulfate (ammonium persulfate APS, the molar ratio of the oxidant to aniline is 1:1), and carry out an in-situ polymerization reaction under a 0.5 T parallel magnetic field (in the same direction as the magnetic field in Step 1), react in an ice bath (0 - 5 °C) for 4 - 6 h. After the reaction is completed, remove the unreacted monomers and by-products by alternating centrifugation (3000 rpm) - deionized water washing, and vacuum dry at 60 °C for 12 h to obtain a composite powder of magnetic nanochains coated with polyaniline; Step 3: Material forming and performance optimization: Mix the composite powder and polyimide PI precursor solution (mass ratio 1:2 - 1:4) in proportion, add the solvent N-methylpyrrolidone NMP to adjust the viscosity to 500 - 1000 cP, and form a film on the surface of the PI film or pretreated aramid fiber substrate by the doctor blade coating method with a coating thickness of 0.5 - 2.0 mm. Subsequently, cure by stepwise heating in a nitrogen atmosphere: pre-cure at 80 °C for 1 h → thermally imidize at 180 °C for 2 h → anneal at 250 °C for 20 min. After curing, cut off the edge burrs and perform plasma surface activation treatment (Ar atmosphere, power 50 W, time 5 min).

[0016] Example: A magnetron-controlled chain-like polyaniline-based broadband biomimetic microwave absorbing material, comprising: Polyaniline matrix (accounting for 82%): Existing in the form of hydrochloric acid-doped Emeraldine salt, with a number average molecular weight (Mn) of 15,000 - 25,000 and a conductivity of 3 - 5 S / cm; Magnetic nanochains (accounting for 17%): Formed by assembling particles with a particle size distribution of 25 ± 5 nm into a chain-like structure induced by a 1.2 T magnetic field. The single-chain length is 5 - 8 μm, the particle spacing within the chain is 8 - 12 nm, and the chain spacing is 100 - 120 nm; Coupling dopant (accounting for 1%): Dioctyl phthalate (DOP) and sodium dodecylbenzenesulfonate (SDBS) are compounded according to a mass ratio of 2:1; Flexible substrate adaptation layer: A polyimide (PI) film with a thickness of 0.8 mm (thermal expansion coefficient ≤ 3 ppm / °C).

[0017] A preparation method of a magnetron-controlled chain-like polyaniline-based broadband biomimetic microwave absorbing material, comprising: Step 1: In-situ magnetron assembly of nanochains: Add commercial nanoparticles (particle size 25 nm, purity ≥ 99.8%) to a deionized aqueous solution containing 1.5% polyvinylpyrrolidone (PVP, K value 27 - 33) to prepare a suspension with a mass concentration of 8%. Disperse it for 15 min with a 300 W ultrasonic cell disruptor under ice bath conditions to ensure that the nanoparticles are non-agglomerated. Inject the suspension into a magnetic field reactor (background magnetic field strength 1.2 T, direction perpendicular to the substrate), heat to 70 ± 1 °C, keep the temperature constant for 2 h, monitor the dynamic arrangement of particles with a high-speed camera during this period, adjust the magnetic field uniformity error ≤ 2%. After the reaction is completed, quickly immerse the sample in liquid nitrogen to freeze and solidify the chain structure, and then vacuum freeze-dry at -50 °C for 24 h to obtain nanoparticle chain preforms; Step 2: In-situ chemical synthesis and coating of polyaniline: The nanocrystal preform was uniformly dispersed in 1 M HCl solution, and aniline monomer (purified by secondary vacuum distillation) was added in a ratio of :aniline = 1:20 (molar ratio). Subsequently, DOP (0.6%) and SDBS (0.4%) were added, and the mixture was ultrasonically premixed until the conductivity of the system was stabilized at 100 μS / cm ± 3%. Under the condition of continuously applying a 1.0 T parallel magnetic field (the direction was precisely controlled by an electromagnetic coil), an ammonium persulfate (APS) solution (aniline:APS = 1:1 molar ratio) was added dropwise at a rate of 0.5 mL / min. The reaction temperature was maintained at 0 ± 0.5 °C (circulating water cooling system). After polymerization for 4 h, the unreacted monomers and oligomers were removed by gradient centrifugation: successively at 500 rpm (to remove large particle impurities), 3000 rpm (to collect the composite), 8000 rpm (to purify the interfacial adsorbent), and this was repeated 3 times. After production, it was vacuum dried at 60 °C for 12 h to obtain the magnetic composite powder.

[0018] Step 3: Material forming and performance optimization: The composite powder and the polyimide precursor (PMDA-ODA type, solid content 18%) were mixed at a mass ratio of powder:PI solution = 1:3, and NMP solvent was added to adjust the viscosity to 800 cP. Doctor blade coating was carried out in a clean and dust-free room: A liquid film with a thickness of 1.2 mm was coated on the surface of the pretreated PI film (activated by oxygen plasma for 60 s), and a laser thickness gauge was used to dynamically monitor the error ≤ 0.1 mm. The curing process: Stepwise temperature rise curing under nitrogen protection: pre-curing at 80 °C for 1 h → thermal imidization at 180 °C for 2 h → annealing at 250 °C for 20 min, with a heating rate of 2 °C / min. The surface roughness Ra of the obtained microwave absorbing film was ≤ 0.2 μm and it could be conformally compounded directly with the thin film antenna feeder layer.

[0019] It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description, and all such improvements and transformations should fall within the protection scope of the appended claims of the present invention.

Claims

1. A magnetically controlled chain-like polyaniline-based broadband biomimetic microwave absorbing material, characterized in that, Including: Polyaniline matrix: accounting for 70%-85%, with conductive polyaniline as the main body; Magnetic nanochains: composed of magnetite A chain-like structure formed by the directional alignment of nanoparticles under the induction of a magnetic field, with a proportion of 10% - 25% and a particle size of 20 - 50 nm; Coupling dopant: a compound system of dioctyl phthalate DOP and sodium dodecylbenzenesulfonate SDBS, accounting for 1%-3%; Flexible substrate adaptation layer: polyimide film PI or aramid fiber reinforced epoxy resin-based film, with a thickness of 0.1-1.5 mm.

2. The broadband biomimetic microwave absorbing material based on magnetically controlled chain-like polyaniline according to claim 1, characterized in that, The single-chain length of the magnetic nanochains is 2-10 μm, the chain spacing is 50-150 nm, and the inter-particle spacing within the chain is 5-15 nm to suppress high-frequency eddy current losses.

3. The magnetically controlled chain-like polyaniline-based broadband biomimetic microwave absorbing material according to claim 2, characterized in that, The degree of orientation of the magnetic nanochains in the polyaniline matrix is ≥80%, and the chain direction is perpendicular to the substrate plane to achieve multi-stage resonance of electromagnetic waves along the chain length direction.

4. The magnetically controlled chain-like polyaniline-based broadband biomimetic microwave absorbing material according to claim 3, wherein, The polyaniline matrix is in-situ coated on the surface of the nanowires to form a "coral-like" coating structure with a thickness of 10-30 nm, ensuring atomic-level contact between the magnetic and electrical components.

5. The magnetically controlled chain-like polyaniline-based broadband biomimetic microwave absorbing material according to claim 4, wherein The overall density of the bionic microwave absorbing material is ≤1.6 g / cm³, the reflection loss is ≤ -25 dB in the range of 8-18 GHz, and the effective absorption bandwidth is ≥8 GHz when the thickness is ≤2 mm.

6. The magnetically controlled chain-like polyaniline-based broadband biomimetic microwave absorbing material according to claim 5, wherein, The mass ratio of DOP to SDBS in the coupling dopant is 2:1, and it is in-situ bonded to the surface of the magnetic nanochains during the polyaniline polymerization stage.

7. A preparation method of a magnetically controlled chain-like polyaniline-based broadband biomimetic microwave absorbing material for preparing the magnetically controlled chain-like polyaniline-based broadband biomimetic microwave absorbing material described in any one of claims 1 to 6, characterized in that, Including the following steps: Step 1: In-situ magnetron assembly of nanochains: Disperse nanoparticles in an aqueous solution containing polyvinylpyrrolidone (PVP), and self-assemble them into a chain-like structure under a perpendicular magnetic field of 0.5 - 1.5 T; Step 2: In-situ chemical synthesis and coating of polyaniline: Under a parallel magnetic field, using nanochains as a template, aniline monomers are polymerized by an oxidant at 0-5 °C; Step three: Material forming and performance optimization: Mix and coat the composite powder with the polyimide precursor, and stepwise cure to form a microwave absorbing film.

8. The preparation method of a magnetically controlled chain-like polyaniline-based broadband biomimetic microwave absorbing material according to claim 7, characterized in that, In step one, the vertical magnetic field strength is 1.0 T, the reaction temperature is 60-80 °C, the reaction time is 1-3 h, and after self-assembly, it is frozen and cured by liquid nitrogen and then vacuum dried.

9. The preparation method of a magnetically controlled chain-like polyaniline-based broadband bionic microwave absorbing material according to claim 8, characterized in that, In the second step described above The molar ratio of [substance] to aniline is 1:15 - 1:25, the molar ratio of ammonium persulfate as the oxidant to aniline is 1:1, and a 0.5 T parallel magnetic field is applied throughout the process.

10. The preparation method of a magnetically controlled chain-like polyaniline-based broadband biomimetic microwave absorbing material according to claim 9, characterized in that, The curing process in step three includes: pre-curing at 80 °C for 1 h; thermal imidization at 180 °C for 2 h; annealing at 250 °C for 20 min; During the curing process, the mass ratio of the composite powder to the polyimide precursor is 1:2 - 1:4, and the coating thickness is 0.5-2.0 mm.

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