A smart electromagnetic wave absorbing composite material based on CoFe-PBA@MXene / PNIPAM and a preparation method thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2026-04-21
- Publication Date
- 2026-06-23
AI Technical Summary
Existing electromagnetic absorbing materials are difficult to dynamically control and reversibly switch their absorption state, and lack periodic lattice structure designs that are compatible with temperature-sensitive gel materials, resulting in the materials being unable to effectively transform changes in external environment into significant changes in electromagnetic absorption performance.
By combining CoFe-PBA@MXene with PNIPAM thermosensitive gel, a CoFe-PBA@MXene/PNIPAM composite system was constructed. Combined with a periodic lattice structure design that can be closely laid up, the synergistic regulation of the reconstruction of the internal electromagnetic network and the macroscopic structural changes of the material under temperature stimulation was achieved. CoFe-PBA@MXene provides conductive loss and interfacial polarization loss, while PNIPAM provides a reversible swelling-shrinkage response. The periodic lattice structure amplifies the difference in electromagnetic response before and after the phase transition.
It realizes the reversible switching of the material's absorption state under temperature stimulation, enhances the interface polarization capability and electromagnetic loss capability, improves the controllability and response difference of the absorption performance, and has the function of temperature-responsive electromagnetic absorption switch.
Smart Images
Figure CN122255646A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of materials science and relates to a temperature-sensitive gel electromagnetic wave absorbing switch and its preparation method. Specifically, it relates to an intelligent electromagnetic wave absorbing composite material based on the CoFe-PBA@MXene / PNIPAM composite system, which can switch electromagnetic wave absorbing states under temperature stimulation and its preparation method. Background Technology
[0002] With the development of electromagnetic stealth protection for aerospace equipment, electromagnetic compatibility of electronic devices, and intelligent electromagnetic control technology, electromagnetic functional materials not only need to possess excellent microwave absorption capabilities but also need to be able to adjust and switch their absorption states according to changes in the external environment to meet the application requirements of dynamic response and functional reconfigurability under complex working conditions. Most existing electromagnetic microwave absorbing materials belong to static absorption systems, whose absorption frequency band and absorption intensity are basically fixed after fabrication, making it difficult to achieve active switching of absorption states. Thermosensitive materials can undergo reversible structural changes under varying external temperature conditions, providing a new approach for constructing dynamic electromagnetic microwave absorbing materials. Simultaneously, CoFe-PBA@MXene composite functional fillers possess good interfacial polarization capabilities and electromagnetic loss characteristics, making them suitable for introduction as functional components into microwave absorbing systems. Summary of the Invention
[0003] To address the shortcomings of existing dynamic electromagnetic absorbing materials, such as insufficient intelligent response control and difficulty in reversibly switching absorption states, as well as the lack of periodic lattice structure design methods compatible with temperature-sensitive gel materials and the difficulty in effectively converting material temperature response into significant changes in electromagnetic absorption performance, this invention provides an intelligent electromagnetic absorbing composite material based on a CoFe-PBA@MXene / PNIPAM composite system and its preparation method. This invention combines CoFe-PBA@MXene with PNIPAM temperature-sensitive gel to construct a CoFe-PBA@MXene / PNIPAM temperature-sensitive composite system. Furthermore, by incorporating a periodic lattice structure design with a close-layout pattern, it achieves synergistic control of the reconstruction of the internal electromagnetic network and changes in macroscopic structural dimensions under temperature stimulation. CoFe-PBA@MXene, as a composite electromagnetic functional filler, provides conductive loss and interfacial polarization loss; PNIPAM, as a temperature-sensitive matrix, provides a reversible swelling-contraction response; and the periodic lattice structure amplifies the difference in electromagnetic response before and after the phase transition. This enables reversible switching of the composite material's absorption state, resulting in a temperature-sensitive electromagnetic absorbing function with obvious switching characteristics.
[0004] The objective of this invention is achieved through the following technical solution:
[0005] A smart electromagnetic wave absorbing composite material based on the CoFe-PBA@MXene / PNIPAM composite system is made of a PNIPAM thermosensitive hydrogel matrix and a CoFe-PBA@MXene composite functional filler, wherein:
[0006] The PNIPAM thermosensitive hydrogel matrix is composed of N-isopropylacrylamide, crosslinking agent, initiator and accelerator;
[0007] The mass ratio of the CoFe-PBA@MXene composite functional filler to N-isopropylacrylamide is 0.5–10:100;
[0008] The crosslinking agent is N,N'-methylenebisacrylamide, and its addition amount is 1-3 wt% of the mass of N-isopropylacrylamide;
[0009] The initiator is ammonium persulfate, and its addition amount is 1-2 wt% of the mass of N-isopropylacrylamide.
[0010] The accelerator is N,N,N',N'-tetramethylethylenediamine, and its addition amount is 0.05-0.30 wt% of the mass of N-isopropylacrylamide;
[0011] The surface of the intelligent electromagnetic wave absorbing composite material is provided with a periodic dot matrix structure, which is composed of geometric units arranged periodically, with a predetermined gap between adjacent geometric units, thereby forming a periodic dot matrix pattern with regular gaps; the geometric units can be selected from squares, equilateral triangles, and regular hexagons.
[0012] A method for preparing the above-mentioned intelligent electromagnetic absorbing composite material based on the CoFe-PBA@MXene / PNIPAM composite system includes the following steps:
[0013] Step 1: Mix the CoFe-PBA precursor system with the MXene dispersion system to allow CoFe-PBA to grow in situ on the MXene surface, thus obtaining the CoFe-PBA@MXene composite functional filler.
[0014] Step 2: Disperse the CoFe-PBA@MXene composite functional filler obtained in Step 1 in deionized water, then add N-isopropylacrylamide monomer, crosslinking agent, initiator and accelerator, and mix evenly to obtain the CoFe-PBA@MXene / PNIPAM thermosensitive composite hydrogel precursor solution.
[0015] Step 3: Inject the temperature-sensitive composite hydrogel precursor liquid obtained in Step 2 into a mold with a periodic lattice structure cavity, and polymerize and form it under room temperature, vacuum, and oxygen-free conditions to obtain a temperature-sensitive composite hydrogel sample with a periodic lattice structure.
[0016] Step 4: Demold the sample obtained in Step 3 and wash it with deionized water to remove unreacted monomers and impurities, thus obtaining the intelligent electromagnetic wave absorbing composite material based on the CoFe-PBA@MXene / PNIPAM composite system.
[0017] Compared with the prior art, the present invention has the following advantages:
[0018] This invention introduces a CoFe-PBA@MXene composite functional filler into the PNIPAM temperature-sensitive gel system and combines it with a periodic lattice structure design to successfully achieve reversible switching of the material's electromagnetic absorption state under temperature stimulation, thus obtaining a temperature-responsive electromagnetic absorption switch function. Compared with existing static absorbing materials, this invention can exhibit different absorption characteristics under different temperature conditions, transforming the absorption performance from a fixed state to a controllable and switchable state. Simultaneously, the introduction of the CoFe-PBA@MXene composite functional filler enhances the material's interfacial polarization and electromagnetic loss capabilities, improving the difference in absorption response before and after temperature changes; the periodic lattice structure further amplifies the changes in structural size and equivalent electromagnetic response before and after the phase transition, thereby increasing the severity of the absorption switch effect. Therefore, this invention not only possesses dynamic electromagnetic absorption functionality under temperature response but also has good functional designability and application expansion value, making it suitable for fields such as intelligent electromagnetic control, stealth protection, and electromagnetic compatibility. Attached Figure Description
[0019] Figure 1 Scanning electron microscope images of cross-sections of PNIPAM thermosensitive gel before and after phase transition shrinkage;
[0020] Figure 2 To actually fabricate hydrogel samples with periodic lattices before and after phase transition shrinkage;
[0021] Figure 3 Schematic diagrams of three periodic dot matrix patterns and their parametric design;
[0022] Figure 4 The graph shows the performance of CoFe-PBA@MXene / PNIPAM hydrogel before and after phase transition shrinkage, as determined by the bow method. Detailed Implementation
[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.
[0024] This invention provides a smart electromagnetic absorbing composite material based on CoFe-PBA@MXene, wherein the smart electromagnetic absorbing composite material is made of a PNIPAM thermosensitive hydrogel matrix and a CoFe-PBA@MXene composite functional filler, wherein:
[0025] The PNIPAM thermosensitive hydrogel matrix is composed of N-isopropylacrylamide, crosslinking agent, initiator and accelerator;
[0026] The mass ratio of the CoFe-PBA@MXene composite functional filler to N-isopropylacrylamide is 0.5–10:100;
[0027] The crosslinking agent is N,N'-methylenebisacrylamide, and its addition amount is 1-3 wt% of the mass of N-isopropylacrylamide;
[0028] The initiator is ammonium persulfate, and its addition amount is 1-2 wt% of the mass of N-isopropylacrylamide.
[0029] The accelerator is N,N,N',N'-tetramethylethylenediamine, and its addition amount is 0.05-0.30 wt% of the mass of N-isopropylacrylamide;
[0030] The CoFe-PBA@MXene composite functional filler is made of Ti3C2T x MXene and CoFe-PBA are in situ composites. PNIPAM thermosensitive gel serves as the matrix to provide a reversible swelling-shrinkage response under temperature stimulation. CoFe-PBA@MXene composite functional filler serves as a conductive and polarizing functional component to provide conductive loss, interfacial polarization loss, and impedance matching adjustment capabilities. Furthermore, combined with a periodic lattice structure design, a periodic lattice unit composed of three types of tileable patterns (square, equilateral triangle, and regular hexagon) and the gaps within it are constructed to make the internal conductive network and macroscopic geometry of the material change synchronously under temperature changes, thereby achieving reversible switching of the electromagnetic wave absorption state.
[0031] This invention also provides a method for preparing the above-mentioned intelligent electromagnetic absorbing composite material based on the CoFe-PBA@MXene / PNIPAM composite system, the method comprising the following steps:
[0032] Step 1: Preparation of Ti3C2T x MXene was obtained, and CoFe-PBA was prepared by co-precipitation. Subsequently, the CoFe-PBA precursor system was mixed with the MXene dispersion system to allow CoFe-PBA to grow in situ on the MXene surface, thus obtaining the CoFe-PBA@MXene composite functional filler.
[0033] Step 2: Disperse the CoFe-PBA@MXene composite functional filler obtained in Step 1 in deionized water, then add N-isopropylacrylamide monomer, crosslinking agent, initiator and accelerator, and mix evenly to obtain the CoFe-PBA@MXene / PNIPAM thermosensitive composite hydrogel precursor solution.
[0034] Step 3: Inject the temperature-sensitive composite hydrogel precursor liquid obtained in Step 2 into a mold with a periodic lattice structure cavity, and polymerize and form it under room temperature, vacuum, and oxygen-free conditions to obtain a temperature-sensitive composite hydrogel sample with a periodic lattice structure.
[0035] Step 4: Demold the sample obtained in Step 3 and wash it with deionized water to remove unreacted monomers and impurities, thus obtaining a temperature-sensitive gel electromagnetic wave absorbing switch material based on the CoFe-PBA@MXene / PNIPAM composite system.
[0036] like Figure 3 As shown, the periodic lattice structure of this invention uses one of the following geometric units—square, equilateral triangle, and regular hexagon—arranged periodically, with a predetermined width of gap between adjacent units to form a periodic lattice pattern with regular gaps. Here, parameter N represents the number of complete periodic units contained along the actual length of the hydrogel sheet, i.e., the number of complete periods along the sample length. By adjusting the value of N, the size of the periodic units, the array density, and the distribution state between units can be controlled. The periodic lattice structure amplifies the differences in unit gaps and equivalent electromagnetic responses before and after temperature stimulation, causing synchronous changes in the internal conductive network, interface contact state, and macroscopic structural dimensions of the material under temperature changes. This results in changes in reflection loss and effective absorption bandwidth, ultimately achieving an electromagnetic wave-absorbing switch function.
[0037] Figure 1 The shrinkage behavior of the hydrogel after phase transition is demonstrated. Microscopically, it is manifested as a decrease in pore size and channel collapse, while macroscopically, it is manifested as a volume shrinkage of the hydrogel.
[0038] Figure 2 The morphological changes of the prepared hydrogel lattice before and after the phase transition are shown, and it can be seen that the macroscopic volume shrinkage and the inter-lattice spacing increase.
[0039] Figure 4 The results of the reflection loss (RL) test of the triangular array before and after shrinkage are shown, which clearly demonstrate that the present invention realizes the electromagnetic wave absorbing switch function before and after the shrinkage of the temperature-sensitive gel.
[0040] Example 1
[0041] Step 1: Weigh 0.95 g LiF and add it to 22 mL of 9 mol / L HCl. Stir until completely dissolved, then slowly add 1.00 g Ti3AlC2 powder and react at 35 ℃ for 22 h. After the reaction is complete, wash repeatedly with deionized water and centrifuge until the pH of the supernatant is close to neutral. Then add deionized water, sonicate for 55 min under ice-water bath conditions, centrifuge, collect the supernatant, and freeze-dry for 40 h to obtain Ti3C2T. x MXene powder.
[0042] Step 2: Weigh 0.10 g of Ti3C2T x MXene was dispersed in 100 mL of deionized water and sonicated in an ice-water bath for 25 min. Separately, 0.152 g of Co(NO3)2·6H2O and 0.148 g of trisodium citrate were dissolved in 20 mL of deionized water to prepare solution A; 0.172 g of K3[Fe(CN)6] was dissolved in 20 mL of deionized water to prepare solution B. Solution A was first added to the MXene dispersion and stirred for 25 min, then solution B was slowly added dropwise, and the reaction continued for 6 h. The resulting product was centrifuged, washed, and freeze-dried for 24 h to obtain the CoFe-PBA@MXene composite functional filler.
[0043] Step 3: Weigh 0.035 g CoFe-PBA@MXene and add it to 20 mL of deionized water. Disperse the solution by sonication in an ice-water bath for 20 min. Add 2.15 g N-isopropylacrylamide (NIPAM) and 0.032 g N,N'-methylenebisacrylamide (BIS) and stir until fully dissolved. Add 0.027 g ammonium persulfate (APS) and purge with argon for 15 min to remove oxygen. Finally, add 30 μL N,N,N',N'-tetramethylethylenediamine (TEMED) and mix quickly to obtain the precursor solution.
[0044] Step 4: Inject the obtained precursor solution into a 3D-printed periodic lattice mold. The mold base layer thickness is 2 mm, the lattice height is 6 mm, the side length of the equilateral triangle is 5.8 mm, and the gap between adjacent units is 1.0 mm. After injection molding, degas under a vacuum of 0.08 MPa for 10 min, and then polymerize at 25 ℃ for 8 h under anaerobic conditions. After polymerization, demold and wash in deionized water for 24 h, changing the water every 8 h to obtain a temperature-sensitive composite gel sample.
[0045] Example 2
[0046] Step 1: Add 1.00 g LiF to 20 mL of 9 mol / L HCl, stir to dissolve, then add 1.05 g Ti3AlC2 powder and react at 35 ℃ for 24 h. After the reaction is complete, wash repeatedly with deionized water and centrifuge until the pH is close to neutral, then sonicate for 50 min, and finally freeze-dry for 48 h to obtain Ti3C2T. x MXene powder.
[0047] Step 2: Weigh 0.12 g Ti3C2T x MXene was dispersed in 110 mL of deionized water and sonicated for 30 min. Then, 0.155 g Co(NO3)2·6H2O and 0.152 g trisodium citrate were dissolved in 22 mL of deionized water to prepare solution A; 0.176 g K3[Fe(CN)6] was dissolved in 20 mL of deionized water to prepare solution B. Solution A was first added to the MXene dispersion system and stirred for 30 min, then solution B was slowly added dropwise, and the reaction continued for 5 h. The reaction product was centrifuged, washed, and freeze-dried to obtain the CoFe-PBA@MXene composite functional filler.
[0048] Step 3: Weigh 0.070 g CoFe-PBA@MXene and add it to 20 mL of deionized water. Sonicate in an ice-water bath for 25 min. Add 2.3 g NIPAM and 0.038 g BIS and stir until completely dissolved. Add 0.030 g APS and purge with argon for 18 min to remove oxygen. Finally, add 32 μL TEMED and mix well to obtain the precursor solution.
[0049] Step 4: Inject the precursor solution into the same periodic lattice mold as in Example 1, maintaining a substrate layer thickness of 2 mm, a lattice height of 6 mm, an equilateral triangle side length of 6.0 mm, and a gap between adjacent units of 1.0 mm. Then, degas under a vacuum of 0.08 MPa for 10 min, and polymerize at 24 ℃ for 9 h under anaerobic conditions. After demolding, wash in deionized water for 30 h, changing the water every 6 h, to obtain a temperature-sensitive composite gel sample.
[0050] Example 3
[0051] Step 1: Add 1.05 g LiF to 20 mL of 9 mol / L HCl, stir well, then add 1.10 g Ti3AlC2 powder, and react at 36 ℃ for 24 h. After the reaction is complete, wash repeatedly with deionized water and centrifuge until the supernatant is nearly neutral, then sonicate for 60 min and freeze-dry for 44 h to obtain Ti3C2T. x MXene powder.
[0052] Step 2: Weigh 0.12 g Ti3C2T x MXene was dispersed in 100 mL of deionized water and sonicated for 35 min. Solution A was prepared by dissolving 0.160 g Co(NO3)2·6H2O and 0.155 g trisodium citrate in 20 mL of deionized water; solution B was prepared by dissolving 0.180 g K3[Fe(CN)6] in 22 mL of deionized water. Solution A was first added to the MXene dispersion and stirred for 30 min, followed by the dropwise addition of solution B and a continued reaction for 6 h. The product was centrifuged, washed, and freeze-dried to obtain the CoFe-PBA@MXene composite functional filler.
[0053] Step 3: Weigh 0.095 g CoFe-PBA@MXene and add it to 20 mL of deionized water. Sonicate in an ice-water bath for 30 min. Add 2.45 g NIPAM and 0.040 g BIS and stir until completely dissolved. Add 0.034 g APS and purge with argon for 18 min to remove oxygen. Finally, add 36 μL TEMED and mix quickly to obtain the precursor solution.
[0054] Step 4: The precursor solution was injected into a periodic lattice mold. The mold base layer thickness was 2 mm, the lattice height was 8 mm, the square side length was 10 mm, and the gap between adjacent units was 0.8 mm. After injection molding, the mixture was degassed under a vacuum of 0.08 MPa for 12 min, followed by polymerization at 22 ℃ for 10 h under anaerobic conditions. After polymerization, the mixture was demolded and washed in deionized water for 36 h, with the water changed every 6 h, to obtain a temperature-sensitive composite gel sample.
[0055] Example 4
[0056] Step 1: Add 1.05 g LiF to 20 mL of 9 mol / L HCl, stir well, then add 1.10 g Ti3AlC2 powder, and react at 36 ℃ for 24 h. After the reaction is complete, wash repeatedly with deionized water and centrifuge until the supernatant is nearly neutral, then sonicate for 60 min and freeze-dry for 44 h to obtain Ti3C2T. x MXene powder.
[0057] Step 2: Weigh 0.12 g Ti3C2T xMXene was dispersed in 100 mL of deionized water and sonicated for 35 min. Solution A was prepared by dissolving 0.160 g Co(NO3)2·6H2O and 0.155 g trisodium citrate in 20 mL of deionized water; solution B was prepared by dissolving 0.180 g K3[Fe(CN)6] in 22 mL of deionized water. Solution A was first added to the MXene dispersion and stirred for 30 min, followed by the dropwise addition of solution B and a continued reaction for 6 h. The product was centrifuged, washed, and freeze-dried to obtain the CoFe-PBA@MXene composite functional filler.
[0058] Step 3: Weigh 0.095 g CoFe-PBA@MXene and add it to 20 mL of deionized water. Sonicate in an ice-water bath for 30 min. Add 2.45 g NIPAM and 0.040 g BIS and stir until completely dissolved. Add 0.034 g APS and purge with argon for 18 min to remove oxygen. Finally, add 36 μL TEMED and mix quickly to obtain the precursor solution.
[0059] Step 4: The precursor solution was injected into a periodic lattice mold. The mold base layer thickness was 2 mm, the lattice height was 6 mm, the side length of the regular hexagon was 0.4 mm, and the gap between adjacent units was 0.6 mm. After injection molding, the mixture was degassed under a vacuum of 0.08 MPa for 14 min, followed by polymerization at 22 ℃ for 10 h under anaerobic conditions. After polymerization, the mixture was demolded and washed in deionized water for 36 h, with the water changed every 6 h, to obtain a temperature-sensitive composite gel sample.
Claims
1. A smart electromagnetic wave absorbing composite material based on the CoFe-PBA@MXene / PNIPAM composite system, characterized in that... The intelligent electromagnetic wave absorbing composite material is made of a PNIPAM temperature-sensitive hydrogel matrix and a CoFe-PBA@MXene composite functional filler, wherein: The PNIPAM thermosensitive hydrogel matrix is composed of N-isopropylacrylamide, crosslinking agent, initiator and accelerator; The mass ratio of the CoFe-PBA@MXene composite functional filler to N-isopropylacrylamide is 0.5–10:100; The amount of the crosslinking agent added is 1 to 3 wt% of the mass of N-isopropylacrylamide; The amount of the initiator added is 1 to 2 wt% of the mass of N-isopropylacrylamide; The amount of the accelerator added is 0.05 to 0.30 wt% of the mass of N-isopropylacrylamide; The surface of the intelligent electromagnetic wave absorbing composite material is provided with a periodic dot matrix structure.
2. The intelligent electromagnetic wave absorbing composite material based on the CoFe-PBA@MXene / PNIPAM composite system according to claim 1, characterized in that... The crosslinking agent is N,N'-methylenebisacrylamide.
3. The intelligent electromagnetic wave absorbing composite material based on the CoFe-PBA@MXene / PNIPAM composite system according to claim 1, characterized in that... The initiator is ammonium persulfate.
4. The intelligent electromagnetic absorbing composite material based on the CoFe-PBA@MXene / PNIPAM composite system according to claim 1, characterized in that... The accelerator is N,N,N',N'-tetramethylethylenediamine.
5. The intelligent electromagnetic wave absorbing composite material based on the CoFe-PBA@MXene / PNIPAM composite system according to claim 1, characterized in that... The periodic dot matrix structure is formed by the periodic arrangement of geometric units, with a predetermined gap between adjacent geometric units, thereby forming a periodic dot matrix pattern with regular gaps.
6. The intelligent electromagnetic wave absorbing composite material based on the CoFe-PBA@MXene / PNIPAM composite system according to claim 5, characterized in that... The geometric unit can be selected from one of the following: square, equilateral triangle, or regular hexagon.
7. A method for preparing the intelligent electromagnetic absorbing composite material based on the CoFe-PBA@MXene / PNIPAM composite system as described in any one of claims 1-6, characterized in that... The method includes the following steps: Step 1: Mix the CoFe-PBA precursor system with the MXene dispersion system to allow CoFe-PBA to grow in situ on the MXene surface, thus obtaining the CoFe-PBA@MXene composite functional filler. Step 2: Disperse the CoFe-PBA@MXene composite functional filler obtained in Step 1 in deionized water, then add N-isopropylacrylamide monomer, crosslinking agent, initiator and accelerator, and mix evenly to obtain the CoFe-PBA@MXene / PNIPAM thermosensitive composite hydrogel precursor solution. Step 3: Inject the temperature-sensitive composite hydrogel precursor liquid obtained in Step 2 into a mold with a periodic lattice structure cavity, and polymerize and form it under room temperature, vacuum, and oxygen-free conditions to obtain a temperature-sensitive composite hydrogel sample with a periodic lattice structure. Step 4: Demold the sample obtained in Step 3 and wash it with deionized water to remove unreacted monomers and impurities, thus obtaining the intelligent electromagnetic wave absorbing composite material based on the CoFe-PBA@MXene / PNIPAM composite system.