A perfluorinated shell interfacial homologized ptf composite dielectric material and a preparation method thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WUHAN UNIV OF TECH
- Filing Date
- 2026-02-27
- Publication Date
- 2026-05-26
Smart Images
Figure CN122080554A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer composite media materials technology, specifically to a PTFE composite media material with homogenized perfluorinated shell interface and its preparation method. Background Technology
[0002] With the rapid development of 5G / 6G communication, millimeter-wave radar, and high-frequency, high-speed packaging devices, more stringent requirements have been placed on dielectric materials to simultaneously possess high dielectric constant, low dielectric loss, and excellent frequency stability under high-frequency conditions. Polytetrafluoroethylene (PTFE) is widely used as a high-frequency matrix material due to its intrinsically low dielectric loss, excellent chemical stability, and heat resistance. However, PTFE's relatively low dielectric constant (≈2.1) limits its further application in dielectric modulation and device miniaturization. Currently, the introduction of high-dielectric fillers mainly uses reinforcing materials such as titanium dioxide (TiO2) and barium titanate (BaTiO3). In particular, the use of ferroelectric ceramic particles such as barium titanate (BaTiO3) to construct high-k composite dielectrics has become the main approach to improving the dielectric properties of PTFE.
[0003] However, due to the significant differences in surface energy, polarity, and chemical structure between inorganic BaTiO3 and organic PTFE matrices, they generally face two major challenges in composite systems: First, BaTiO3 particles are prone to agglomeration during processing, leading to local electric field distortion and severe degradation of dielectric loss performance; second, even if surface modification achieves a certain degree of dispersion improvement, insufficient interfacial bonding strength still introduces interfacial polarization loss and interfacial defects, making it difficult to achieve synergistic optimization of dielectric properties and loss characteristics under high-frequency conditions. Existing research mostly focuses on single-dimensional optimization in dispersion control or interfacial modification, and has not yet achieved synergistic control of dispersion interface and loss reduction from the perspective of intrinsic chemical compatibility of materials.
[0004] Therefore, there is an urgent need to develop a fundamental strategy to achieve synergistic optimization of filler dispersion control and interfacial polarization loss suppression, so as to "homogenize" heterogeneous interfaces and prepare next-generation high-performance PTFE-based composite dielectric materials with high dielectric constant, ultra-low loss and excellent frequency stability. Summary of the Invention
[0005] In view of this, this invention proposes a PTFE composite dielectric material with homogenized perfluorinated shell interface and its preparation method. Nafion is used to coat the surface of BaTiO3, and a BaTiO3@Nafion / PTFE composite dielectric plate is prepared by combining a PTFE melt hot pressing process. Through the adsorption of sulfonic acid groups in the Nafion molecular chain and the interfacial matching effect of the fluorine segments, the interfacial bonding and dispersion state between barium titanate and PTFE can be significantly improved, ultimately obtaining a PTFE-based composite dielectric material suitable for high-frequency dielectric substrates. The technical solution of this invention is implemented as follows: In a first aspect, the present invention proposes a PTFE composite medium material with homogenized perfluorinated shell interface, comprising: a PTFE matrix, and a core-shell structured filler dispersed in the PTFE matrix; The core-shell structure filler includes a BaTiO3 particle core and a Nafion coating layer that wraps around the surface of the BaTiO3 particles.
[0006] Preferably, the mass of the Nafion coating layer accounts for 0.3 wt.% to 2.5 wt.% of the total mass of the core-shell structure filler.
[0007] Preferably, the mass of the Nafion coating layer accounts for 0.5 wt.% to 2.0 wt.% of the total mass of the core-shell structure filler.
[0008] Preferably, the mass of the core-shell structured filler accounts for 20 wt.% to 60 wt.% of the total mass of the PTFE composite medium material.
[0009] Preferably, the mass of the core-shell structured filler accounts for 40 wt.% of the total mass of the PTFE composite media material.
[0010] Preferably, the particle size of the BaTiO3 particles is 80~120 nm.
[0011] Specifically, particles of this size have relatively stable dielectric properties and a high dielectric constant. Particles larger than this size have a lower dielectric constant, and particles smaller than this size are difficult to make uniform in size.
[0012] In a second aspect, the present invention provides a method for preparing a PTFE composite dielectric material as described in the first aspect, comprising the following steps: S1. Disperse BaTiO3 particles in deionized water, add Nafion solution and stir to react. After the reaction is completed, perform solid-liquid separation, washing and drying to obtain BaTiO3 core-shell structured filler coated with Nafion shell. S2. The BaTiO3 core-shell structure filler coated with Nafion shell obtained in step S1 is mixed with PTFE emulsion and uniformly dispersed to obtain a mixed slurry. S3. The mixed slurry obtained in step S2 is subjected to demulsification and rolling treatment to form composite material preforms; S4. The prefabricated sheet of the composite material obtained in step S3 is subjected to vacuum hot pressing curing to obtain the PTFE composite medium material.
[0013] Preferably, the reaction time of the stirring reaction in step S1 is 24~72h.
[0014] Preferably, the thickness of the composite material preform in step S3 is 0.9~1.1 μm.
[0015] Preferably, the vacuum hot pressing curing temperature in step S4 is 350~380℃, the pressure is 20~50 MPa, and the holding time is 5~9h.
[0016] Specifically, the appropriate stirring time determines the thickness of the coating layer. If the thickness is too thin, it will not be effective, and if the thickness is too thick, it will cause particle adhesion. Therefore, the purpose of the optimized reaction time is to obtain a reasonable range of shell thickness. The purpose of vacuum hot pressing is to melt PTFE at high temperature and then apply pressure to make the material more compact. The melting temperature of PTFE is 350℃. Below 350℃, PTFE cannot melt, and above 380℃, PTFE will decompose. Pressure also determines the density of the material. If the pressure is lower than the optimal pressure, the material will still contain air (pores), and if the pressure is higher than the optimal pressure, it will cause glue overflow, and the material cannot be formed.
[0017] Compared with the prior art, the advantages of the present invention are as follows: (1) The present invention achieves long-term stable dispersion and construction of BaTiO3 filler in PTFE matrix, effectively suppresses agglomeration and re-agglomeration behavior during processing and service, and significantly reduces the risk of local electric field distortion and dielectric loss degradation induced therefrom.
[0018] (2) The present invention constructs a high-matching, low-polarization interface structure that is homologous to the PTFE skeleton, which significantly enhances the bonding strength of the filler-matrix interface and effectively suppresses interface polarization and defect polarization loss, thereby achieving synergistic regulation of dielectric enhancement and ultra-low loss.
[0019] (3) This invention, while utilizing the BaTiO3 core to improve the dielectric constant of the composite material, constructs a low-polarity, high-compatibility "quasi-homogeneous" interface phase, enabling the material to maintain ultra-low dielectric loss characteristics similar to pure PTFE at high frequencies, thus successfully solving the industry problem of the difficulty in synergistically optimizing high dielectric constant and low loss. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 A process flow diagram for preparing PTFE composite dielectric materials provided in embodiments of the present invention; Figure 2 This is a schematic diagram of the dielectric constant curves of composite materials with different BaTiO3 filling amounts prepared in Example 1 of this invention; Figure 3 This is a schematic diagram illustrating the mechanism of action of the Nafion molecule provided in an embodiment of the present invention; Figure 4 TEM image of BaTiO3@Nafion packing provided in the embodiments of the present invention. Figure 5 This is a FT-IR comparison image of BaTiO3 of the present invention and BaTiO3@Nafion filler in Example 1; Figure 6 The images shown are SEM images of the BaTiO3@Nafion / PTFE composite materials obtained in Examples 1-3 of this invention. Figure 7 These are SEM images of the composite materials obtained in Comparative Examples 1-3 of this invention; Figure 8 The dielectric loss diagrams of the composite materials obtained in Examples 1-3 and Comparative Examples 2 and 3 of the present invention are shown in the frequency range of 1-40 GHz. Figure 9 The graph shows the dielectric loss of the composite materials obtained in Examples 1-3 and Comparative Examples 2 and 3 of this invention at a frequency of 20 GHz. Detailed Implementation
[0022] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.
[0023] This invention addresses the critical issues of high interfacial polarization loss and easy filler agglomeration caused by intrinsic mismatch at the organic-inorganic interface in traditional BaTiO3 / PTFE composites. It proposes an in-situ solution based on "structural homology interface design." Unlike the conventional approach of interfacial bridging through external organic coatings, this solution constructs a Nafion shell, a perfluoropolymer with chemical properties homologous to the PTFE matrix, on the surface of BaTiO3 particles, achieving a paradigm shift from a "physically modified interface" to a "chemically integrated interface." This core-shell structure plays a dual role: firstly, the perfluoroshell exhibits excellent intrinsic compatibility with the PTFE matrix, significantly reducing interfacial defects and charge traps, thereby fundamentally suppressing Maxwell-Wagner interfacial polarization that leads to high-frequency losses; secondly, the shell acts as a steric stabilizer in the composite precursor, ensuring nanoscale uniform dispersion of the filler in the matrix and eliminating local electric field distortion and associated losses caused by particle agglomeration. Furthermore, this invention overcomes the problem of poor interfacial compatibility under high filling conditions, and achieves synergistic maximization of high dielectric constant and extremely low dielectric loss. The filler used in this invention achieves perfect dispersion and interfacial fusion while avoiding the "dilution" effect of excessive low-k polymer on the overall dielectric constant of the composite material and the possible introduction of new loss sources, thereby transforming the theoretical advantages of the core-shell structure into a repeatable and industrially achievable high performance.
[0024] Unlike traditional approaches that primarily improve the dispersion behavior or interfacial wettability of BaTiO3 in a PTFE matrix through coupling agent modification, surface polarity modulation, or physical coatings, this study constructs a core-shell filler interface structure with the perfluoropolymer Nafion as the shell, based on the principle of molecular structural homology matching. This strategy does not simply introduce a polar bridging layer to alleviate interfacial mismatch, but rather transforms the filler surface into a chemical environment highly homologous to the PTFE framework. Simultaneously, leveraging the charge repulsion effect and steric stabilization mechanism of Nafion in aqueous systems, the agglomeration behavior of BaTiO3 particles is effectively suppressed, avoiding the technical trade-offs of traditional modifications that either "improve dispersion but sacrifice interfacial compatibility" or "enhanced interfacial bonding but still accompanied by agglomeration." Compared to modification schemes that rely on high-polarity interfacial layers to introduce additional polarization losses, the perfluorinated low-polarity interfacial structure constructed in this study achieves intrinsic suppression of interfacial polarization losses at the mechanistic level, providing a new technique for preparing PTFE-based high-frequency composite dielectric materials with both high dielectric constant and ultra-low dielectric loss.
[0025] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.
[0026] In this document, the terms “containing,” “comprising,” or “including” are open-ended expressions, meaning they include the contents specified in this invention but do not exclude other aspects.
[0027] In this document, the terms “optional,” “optionally,” or “optional” generally refer to an event or condition that may, but may not, occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.
[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.
[0029] like Figure 1 As shown, this embodiment of the invention provides a PTFE composite dielectric material with homogenized perfluorinated shell interface and its preparation method, including the following steps: (1) Weigh 5 g of BaTiO3 nanoparticles and add them to 500 mL of deionized water. Disperse them using ultrasound for 60 min to allow the nanoparticles to fully deagglomerate and form a stable and uniform dispersion. The particle size of the BaTiO3 particles is in the range of 80~120 nm. (2) Add 0g, 0.075g, 0.125g, 0.375g, 0.5g, and 0.625g of Nafion solution with a mass fraction of 20 wt.% to the dispersion in step (1) respectively, and stir magnetically at room temperature for 24~72 h. The purpose is to allow Nafion molecules to adsorb and form a coating layer. After the reaction is completed, use deionized water for centrifugal washing at a speed of 7000~8000 r / min for 5~10 min, repeating 3~5 times to remove unbound Nafion impurities. Then, place the precipitate in a vacuum drying oven and dry it at 80℃ to remove surface moisture. Grind it evenly to obtain Nafion-coated BaTiO3 nanoparticles (BaTiO3@Nafion), which are used as structural fillers for subsequent processes. (3) Add the BaTiO3@Nafion nanoparticles obtained in step (2) to the PTFE emulsion and mix them at high speed using a planetary stirring method with a mixing speed of 2000 r / min, so that the inorganic structure filler is uniformly dispersed in the PTFE emulsion system, thereby obtaining the BaTiO3@Nafion / PTFE organic-inorganic mixed slurry; (4) After adding anhydrous alcohol (30 wt.% of the mass of the mixed slurry) to the mixed slurry in step (3) to break the emulsion, the mixture is folded and rolled to obtain a pre-formed sheet of composite material with a forming thickness of 0.9~1.1 μm; (5) The composite material prefabricated sheet described in step (4) is placed into two steel plates for vacuum hot pressing and curing at a temperature of 350~380℃ and a pressure of 20~50 MPa for 5~9h. After cooling, Nafion-coated BaTiO3 / PTFE composite medium material is obtained.
[0030] The following examples and comparative embodiments further illustrate the specific implementation methods and beneficial effects of the present invention. All materials used in this invention were commercially available. Specifically, the BaTiO3 nanoparticles, Nafion solution, and PTFE emulsion were all purchased from DuPont, USA.
[0031] Preparation Example 1 This preparation example provides a PTFE composite media material and its preparation method. To screen the optimal amount of structural filler, the method includes the following steps: (1) Weigh 0 g, 6 g, 16 g, and 36 g of BaTiO3 nanoparticles as structural fillers and add them to 40 g of PTFE emulsion (water emulsion with a solid content of 60%). Mix them at high speed using a planetary stirring method with a mixing speed of 2000 r / min to make the structural filler uniformly dispersed in the PTFE emulsion system, thereby obtaining BaTiO3 / PTFE organic-inorganic mixed slurry; (2) After adding alcohol to the mixed slurry in step (1) to break the emulsion, the mixture is folded and rolled to obtain a pre-formed sheet of composite material with a forming thickness of 1 μm. (3) The composite material prefabricated sheet described in step (2) is placed in two steel plates for vacuum hot pressing and curing at a temperature of 365°C and a pressure of 35 MPa for 7.5 hours. After cooling, BaTiO3 / PTFE composite medium material is obtained.
[0032] The BaTiO3 / PTFE composite dielectric plate obtained in step (3) was used for dielectric performance testing, with the contents of the structural filler being 0 wt.%, 20 wt.%, 40 wt.%, and 60 wt.% (filler content as a percentage of the total mass of filler and PTFE). Its dielectric constant was tested at 20 GHz, and the effect of filler content on dielectric performance was compared to obtain the results. Figure 2 ; Figure 2 The figure shows the relationship between the dielectric constant of the composite material and its content under different BaTiO3 filling amounts. As can be seen from the figure, the dielectric constant of the composite material gradually increases with the increase of BaTiO3 content. When the filling amount reaches about 40 wt.%, the dielectric constant exceeds 5, which meets the application requirements of high dielectric media. At a filling amount of 60 wt.%, the matrix and filler may separate, resulting in extreme brittleness. Therefore, this study selected 40 wt.% BaTiO3 content as the preferred content for subsequent processes.
[0033] Example 1 This embodiment provides a PTFE composite dielectric material with homogenized perfluorinated shell interface and its preparation method, including the following steps: (1) Weigh 5 g of BaTiO3 nanoparticles and add them to 500 mL of deionized water. Disperse them using ultrasound for 60 min to allow the nanoparticles to fully deagglomerate and form a stable and uniform dispersion. (2) Add 0.125 g of Nafion solution with a mass fraction of 20 wt.% to the dispersion in step (1) and stir magnetically at room temperature for 48 h. After the reaction is completed, centrifuge and wash with deionized water at a speed of 7500 r / min for 7.5 min, repeating 4 times to remove unbound Nafion impurities. Then, place the precipitate in a vacuum drying oven and dry it at 80℃ to remove surface moisture. Grind it evenly to obtain Nafion-coated BaTiO3 nanoparticles (BaTiO3@Nafion) with a coating amount of 0.5 wt.%, which is used as a structural filler for subsequent processes. (3) Add the BaTiO3@Nafion nanoparticles obtained in step (2) to 20g of PTFE emulsion and mix them at high speed using a planetary stirring method with a mixing speed of 2000 r / min to make the inorganic structure filler uniformly dispersed in the PTFE emulsion system, thereby obtaining BaTiO3@Nafion / PTFE organic-inorganic mixed slurry; (4) After adding alcohol to the mixed slurry in step (3) to break the emulsion, the mixture is folded and rolled to obtain a pre-formed sheet of composite material with a forming thickness of 1 μm. (5) The composite material prefabricated sheet described in step (4) is placed in two steel plates for vacuum hot pressing and curing at a temperature of 365°C and a pressure of 35 MPa for 7.5 hours. After cooling, Nafion-coated BaTiO3 / PTFE composite medium material is obtained.
[0034] See Figure 3 The modification process of Nafion-coated BaTiO3 nanoparticles was illustrated with a structural diagram to demonstrate the coating and interface construction mechanism of Nafion molecules on the BaTiO3 surface. Figure 3 The sulfonic acid groups of the Nafion molecule are adsorbed on the surface of BaTiO3 and form an interfacial match with the PTFE matrix through its fluorine segments, thereby forming a continuous interfacial transition layer, which improves the dispersion stability of inorganic fillers in fluoropolymers and significantly improves interfacial compatibility.
[0035] Furthermore, Fourier transform infrared (FT-IR) spectroscopy was performed on BaTiO3 and the BaTiO3@Nafion powder samples obtained in step (2) of Example 1 using the potassium bromide pellet method. Before the test, pure KBr was used to compress the powder into pellets and the background spectrum was collected. Then, approximately 1-1.5 mg of the sample and approximately 150 mg of dry KBr were weighed and thoroughly ground and mixed in an agate mortar, then pressed into thin sheets. The pellets were then heated at 4000-400 cm⁻¹. -1 Spectral scanning was performed within the specified range. A new background film was prepared after each sample test to eliminate environmental interference. The infrared spectra of BaTiO3 and BaTiO3@Nafion were obtained through the above tests, which were used to verify the success of the Nafion coating.
[0036] See Figure 4 The coating state can be seen from the TEM image of BaTiO3@Nafion, see [link / reference]. Figure 5 In the infrared spectrum at 1155 cm⁻¹ -1 1245 cm -1 and 1340 cm -1 The characteristic peaks appearing at the point correspond to the stretching vibrations of CF, and the original characteristic peaks of BaTiO3 still exist. These results confirm that Nafion was successfully coated on the surface of BaTiO3.
[0037] Example 2 This embodiment provides a PTFE composite dielectric material with homogenized perfluorinated shell interface and its preparation method, including the following steps: (1) Weigh 5 g of BaTiO3 nanoparticles and add them to 500 mL of deionized water. Disperse them using ultrasound for 60 min to allow the nanoparticles to fully deagglomerate and form a stable and uniform dispersion. (2) Add 0.375 g of Nafion solution with a mass fraction of 20 wt.% to the dispersion in step (1) and stir magnetically at room temperature for 24 h. After the reaction is completed, centrifuge and wash with deionized water at a speed of 7000 r / min for 5 min, repeating 3 times to remove unbound Nafion impurities. Then, place the precipitate in a vacuum drying oven and dry it at 80℃ to remove surface moisture. Grind it evenly to obtain Nafion-coated BaTiO3 nanoparticles (BaTiO3@Nafion) with a coating amount of 1.5 wt.%, which is used as a structural filler for subsequent processes. (3) Add the BaTiO3@Nafion nanoparticles obtained in step (2) to 20g of PTFE emulsion and mix them at high speed using a planetary stirring method with a mixing speed of 2000 r / min to make the inorganic structure filler uniformly dispersed in the PTFE emulsion system, thereby obtaining BaTiO3@Nafion / PTFE organic-inorganic mixed slurry; (4) After adding alcohol to the mixed slurry in step (3) to break the emulsion, the mixture is folded and rolled to obtain a pre-formed sheet of composite material with a forming thickness of 0.9 μm; (5) The composite material prefabricated sheet described in step (4) is placed in two steel plates for vacuum hot pressing and curing at a temperature of 350°C and a pressure of 20 MPa for 5 hours. After cooling, Nafion-coated BaTiO3 / PTFE composite medium material is obtained.
[0038] Example 3 This embodiment provides a PTFE composite dielectric material with homogenized perfluorinated shell interface and its preparation method, including the following steps: (1) Weigh 5 g of BaTiO3 nanoparticles and add them to 500 mL of deionized water. Disperse them using ultrasound for 60 min to allow the nanoparticles to fully deagglomerate and form a stable and uniform dispersion. (2) Add 0.5 g of Nafion solution with a mass fraction of 20 wt.% to the dispersion in step (1) and stir magnetically at room temperature for 72 h. After the reaction is completed, centrifuge and wash with deionized water at a speed of 8000 r / min for 10 min, repeating 5 times to remove unbound Nafion impurities. Then, place the precipitate in a vacuum drying oven and dry it at 80℃ to remove surface moisture. Grind it evenly to obtain Nafion-coated BaTiO3 nanoparticles (BaTiO3@Nafion) with a coating amount of 2.0 wt.%, which is used as a structural filler for subsequent processes. (3) Add the BaTiO3@Nafion nanoparticles obtained in step (2) to 20g of PTFE emulsion and mix them at high speed using a planetary stirring method with a mixing speed of 2000 r / min to make the inorganic structure filler uniformly dispersed in the PTFE emulsion system, thereby obtaining BaTiO3@Nafion / PTFE organic-inorganic mixed slurry; (4) After adding alcohol to the mixed slurry in step (3) to break the emulsion, the mixture is folded and rolled to obtain a pre-formed sheet of composite material with a forming thickness of 1.1 μm. (5) The composite material prefabricated sheet described in step (4) is placed in two steel plates for vacuum hot pressing and curing at a temperature of 380°C and a pressure of 50 MPa for 9 hours. After cooling, the Nafion-coated BaTiO3 / PTFE composite medium material is obtained.
[0039] Comparative Example 1 The difference between this comparative example and Example 1 is that Nafion solution was not added, while all other aspects remained the same as in Example 1.
[0040] Comparative Example 2 The difference between this comparative example and Example 1 is that in step (2), 0.075 g of Nafion solution was added, that is, the coating amount was 0.3 wt.%, and the rest were the same as in Example 1.
[0041] Comparative Example 3 The difference between this comparative example and Example 1 is that in step (2), 0.625 g of Nafion solution was added, that is, the coating amount was 2.5 wt.%, while the rest were the same as in Example 1.
[0042] See Figure 6 , Figure 6 SEM images of the BaTiO3@Nafion / PTFE composites obtained in Examples 1-3 are shown, corresponding to Nafion contents of 0.5 wt.% to 2 wt.%, respectively. The figures show that an appropriate Nafion coating amount contributes to the uniform mixing of the BaTiO3 / PTFE composite dielectric material. Furthermore, the SEM images demonstrate a tight interfacial bond in the BaTiO3@Nafion / PTFE composites, which is a prerequisite for achieving high dielectric properties.
[0043] See Figure 7 , Figure 7 SEM images of the composite materials obtained in Comparative Examples 1-3 are shown. Figure 7 (a) is a SEM image of the BaTiO3 / PTFE composite material without Nafion coating. As can be seen from the figure, the BaTiO3 particles exhibit severe agglomeration and fail to bind with PTFE. Figure 7(b) is a SEM image of the BaTiO3 / PTFE composite material coated with 0.3 wt.% Nafion. Due to the interfacial compatibility between Nafion and PTFE, the BaTiO3 particles coated with Nafion began to combine with PTFE, but some particles still showed agglomeration. Figure 7 (c) is a SEM image of the BaTiO3 / PTFE composite material coated with 2.5 wt.% Nafion. With the addition of Nafion content, the excess Nafion leads to increased adhesion on the particle surface, resulting in an imbalance of steric hindrance and a decrease in the repulsive ability between particles, which is the reason for its agglomeration phenomenon.
[0044] See Figure 8 , Figure 8 This is a graph showing the variation of dielectric loss performance of the composite dielectric material substrates obtained in Examples 1-3 and Comparative Examples 2-3 at frequencies ranging from 1 to 40 GHz. Figure 8 (a~c) in the examples correspond to Examples 1~3, respectively. They exhibited low dielectric loss in high-frequency testing, and the fluctuation of dielectric loss was small with changes in test frequency, indicating good bonding of their fillers; especially Figure 8 As shown in (b), even under the 40 GHz test, the optimal Nafion BaTiO3 / PTFE system still exhibits a performance below 7.5 × 10⁻⁶. -3 dielectric loss rate; Figure 8 Examples (d) and (e) correspond to Comparative Example 2 and Comparative Example 3, respectively. They exhibit high dielectric loss in high-frequency tests, exceeding 15 × 10⁻⁶ at 40 GHz. -3 .
[0045] See Figure 9 , Figure 9 The graph shows a comparison of dielectric losses at 20 GHz. As can be seen from the graph, the dielectric losses of Examples 1-3 are generally lower than 6 × 10⁻⁶. -3 Compared to the performance of BaTiO3 particles coated with a small amount of Nafion and BaTiO3 particles coated with an excessive amount of Nafion in Comparative Examples 2 and 3, the dielectric loss was reduced by nearly two times. This is because: a small amount of coating results in a thin coating shell, while an excessive amount results in a too thick coating shell; when the thickness is too thin, it is only a "scattered repair interface", and there are still unmodified areas; when the thickness is too thick, it becomes a "third phase participating in polarization and conduction"; only at a moderate thickness does Nafion mainly play the role of interface passivation and dielectric gradient transition, thus most effectively reducing dielectric loss.
[0046] In Comparative Example 1, the unmodified BaTiO3 particles could hardly be effectively dispersed in the PTFE matrix, and obvious particle packing structures were formed in local areas. Its dispersion uniformity was the worst among all comparative examples and embodiments.
[0047] Table 1 shows the effect of different Nafion coating contents on the microstructure and high-frequency dielectric properties of BaTiO3@Nafion / PTFE composite materials. This table summarizes the performance comparison data of the composite materials prepared in Examples 1-3 and Comparative Examples 1-3.
[0048] Table 1. Performance comparison of composite materials prepared in Examples 1-3 and Comparative Examples 1-3
[0049] In summary, this invention provides a PTFE composite dielectric material based on perfluorinated shell interface homogenization and its preparation method. By constructing a core-shell structured filler with Nafion as the shell, it fundamentally solves the core problems of poor filler dispersion and high high-frequency loss caused by intrinsic interfacial mismatch in traditional BaTiO3 / PTFE composite materials. This method is not only technologically feasible, but more importantly, it successfully achieves synergistic optimization of high dielectric constant and ultra-low dielectric loss by precisely controlling the Nafion coating layer within a specific content range of 0.5 wt.% to 2.0 wt.%. The composite material obtained by this invention maintains excellent frequency stability in the millimeter-wave band up to 40 GHz, providing a key high-performance dielectric material solution for next-generation high-frequency and high-speed electronic devices such as 5G / 6G communications and millimeter-wave radar.
[0050] The embodiments described above are some, but not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
Claims
1. A PTFE composite dielectric material with homogenized perfluorinated shell interface, characterized in that, include: PTFE matrix, and core-shell structured filler dispersed in the PTFE matrix; The core-shell structure filler includes a BaTiO3 particle core and a Nafion coating layer that wraps around the surface of the BaTiO3 particles.
2. The PTFE composite dielectric material according to claim 1, characterized in that, The mass of the Nafion coating layer accounts for 0.3 wt.% to 2.5 wt.% of the total mass of the core-shell structure filler.
3. The PTFE composite dielectric material according to claim 2, characterized in that, The mass of the Nafion coating layer accounts for 0.5 wt.% to 2.0 wt.% of the total mass of the core-shell structure filler.
4. The PTFE composite dielectric material according to claim 1, characterized in that, The core-shell structured filler accounts for 20 wt.% to 60 wt.% of the total mass of the PTFE composite medium material.
5. The PTFE composite dielectric material according to claim 4, characterized in that, The core-shell structured filler accounts for 40 wt.% of the total mass of the PTFE composite media material.
6. The PTFE composite dielectric material according to claim 1, characterized in that, The particle size of the BaTiO3 particles is 80~120 nm.
7. A method for preparing the PTFE composite dielectric material as described in claims 1-6, characterized in that, Includes the following steps: S1. Disperse BaTiO3 particles in deionized water, add Nafion solution and stir to react. After the reaction is completed, perform solid-liquid separation, washing and drying to obtain BaTiO3 core-shell structured filler coated with Nafion shell. S2. The BaTiO3 core-shell structure filler coated with Nafion shell obtained in step S1 is mixed with PTFE emulsion and uniformly dispersed to obtain a mixed slurry. S3. The mixed slurry obtained in step S2 is subjected to demulsification and rolling treatment to form composite material preforms; S4. The prefabricated sheet of the composite material obtained in step S3 is subjected to vacuum hot pressing curing to obtain the PTFE composite medium material.
8. The preparation method according to claim 7, characterized in that, The reaction time for the stirring reaction in step S1 is 24~72h.
9. The preparation method according to claim 7, characterized in that, The thickness of the composite material prefabricated sheet in step S3 is 0.9~1.1 μm.
10. The preparation method according to claim 7, characterized in that, The vacuum hot pressing curing temperature in step S4 is 350~380℃, the pressure is 20~50 MPa, and the holding time is 5~9h.