Janus structure functional fabric based on flexible porous PVDF-HFP ferroelectric film and preparation method thereof

Abstract

The invention provides a Janus structure functional fabric based on a flexible porous PVDF-HFP ferroelectric film and a preparation method of the Janus structure functional fabric. An MXene (at) Ag composite conductive antibacterial layer and a porous PVDF-HFP (at) BN-TBAHP ferroelectric layer are sequentially constructed, and a stably combined double-layer heterostructure is formed at an interface; the Janus structure functional fabric material with super-hydrophobic / super-hydrophilic switchable wettability, high thermal stability, mechanical flexibility and antibacterial ability is prepared, and the material not only can realize efficient thermal regulation and humidity management in a complex environment, but also can be used as a structural substrate and a sensing platform of a flexible wearable electronic device; and the device has the remarkable advantages of simple structure, scalable process, high function integration level and strong environmental adaptability.

Description

Technical Field

[0001] This invention relates to the fields of functional textile materials and flexible electronics, and in particular to a Janus structure functional fabric based on a flexible porous PVDF-HFP ferroelectric film and its preparation method. Background Technology

[0002] With the integration of advanced materials science and wearable electronics technology, textiles are evolving from traditional single-function materials into intelligent systems with multiple sensing, control, and protection capabilities. Due to their softness, breathability, and wearability, smart textiles can come into close contact with human skin and respond in real time to changes in the external environment, making them an important carrier for the next generation of personal smart devices.

[0003] Currently, developing high-performance smart textiles that integrate core functions such as human body thermal management, physiological signal monitoring, and biological protection remains a key technological goal that urgently needs to be achieved in this field. In existing technologies, the integration of these functions is constrained by the inherent properties of the materials. For example, the high infrared emissivity or low thermal conductivity required to achieve efficient thermal regulation often conflicts with the design requirements of high-sensitivity sensing layers or efficient antibacterial layers; while the introduction of metal ions or organic bactericides to improve antibacterial performance may lead to decreased stability of the conductive layer or insufficient washability of the fabric.

[0004] Janus-structured materials, with their distinct physicochemical properties on either side of the structural center, offer a feasible solution to the aforementioned functional integration challenges. By designing differentiated functional layers on both sides of the material, spatial division and synergistic regulation of multiple properties such as thermal management, protection, conductivity, and antibacterial properties can be achieved, thus overcoming the limitations of functional coupling in single-layer fabrics. Applying this type of structure to textiles allows for energy and material exchange with the external environment on one side (such as heat dissipation and antibacterial protection), while maintaining comfort and safety on the skin-contacting surface on the other side, significantly improving the overall performance of the fabric.

[0005] In existing technologies, some studies have attempted to combine thermal regulation, antibacterial, and sensing properties through functional composites or multilayer structures, but the overall results remain unsatisfactory. Existing fabric systems generally struggle to achieve effective integration of multiple functions; most designs only offer limited functional combinations, lacking a comprehensive balance between comfort, environmental adaptability, and protective performance. Furthermore, existing fabric structures lack synergistic effects in functional coupling. For example, while high infrared emissivity materials possess good heat dissipation properties, they are prone to surface charge loss or reduced interfacial conductivity; the continuous release of metal ions from the antibacterial layer damages the conductive layer structure, causing an overall performance decline and making long-term stability difficult. Simultaneously, existing preparation processes are complex, with insufficient interfacial bonding; traditional multilayer composites, chemical deposition, or sol-gel methods suffer from poor repeatability and low controllability, hindering large-area continuous production and long-term stability of fabrics.

[0006] Therefore, it is necessary to study a Janus-structured functional fabric based on a flexible porous PVDF-HFP ferroelectric film and its preparation method to address the shortcomings of existing technologies and solve or mitigate one or more of the above-mentioned problems. Summary of the Invention

[0007] In view of this, the present invention provides a Janus-structured functional fabric based on a flexible porous PVDF-HFP ferroelectric film and its preparation method. By sequentially constructing an MXene@Ag composite conductive antibacterial layer and a porous PVDF-HFP@BN-TBAHP ferroelectric layer, and forming a stable bonded bilayer heterostructure at the interface, a Janus-structured functional fabric material with superhydrophobic / superhydrophilic switchable wettability, high thermal stability, mechanical flexibility, and antibacterial ability is obtained. This material can not only achieve efficient thermal regulation and humidity management in complex environments, but also serve as a structural substrate and sensing platform for flexible wearable electronic devices. It has significant advantages such as simple structure, scalable process, high functional integration, and strong environmental adaptability.

[0008] On one hand, the present invention provides a method for preparing a Janus-structured functional fabric based on a flexible porous PVDF-HFP ferroelectric film, the preparation method comprising the following steps: S1, Preparation of MXene / Ag⁺ composite solution: Mix MXene dispersion and silver nitrate solution at a volume ratio of 1:1 to obtain MXene / Ag⁺ composite solution; S2, cotton fabric pretreatment, the cotton fabric is placed in deionized water and anhydrous ethanol in sequence for ultrasonic cleaning and drying for later use. S3, Constructing the MXene@Ag Composite Conductive Layer: Immerse the pretreated cotton fabric in the MXene / Ag⁺ composite solution, stir to allow Ag⁺ to be adsorbed onto the MXene flakes and fiber surface, uniformly spray with ascorbic acid aqueous solution for in-situ reduction, then wash with deionized water and dry to obtain conductive and antibacterial MXene@Ag composite fabric. S4, Preparation of PVDF-HFP precursor solution: Add PVDF-HFP powder to N,N-dimethylacetamide and stir at room temperature until uniform and transparent to obtain PVDF-HFP precursor solution; S5, Add filler and pore structure inducer: Add hexagonal boron nitride nanoparticles to the PVDF-HFP precursor solution and disperse them evenly; then add 0.5–12 wt% of tetrabutylammonium hexafluorophosphate to regulate the micropore structure and ferroelectric phase content of the membrane to obtain a mixed solution; S6, Degassing and Film Formation: The mixed solution is stirred in a water bath and ultrasonically degassed, then drop-coated onto a clean glass substrate. After natural drying at room temperature, it is slowly peeled off to obtain a self-supporting porous PVDF-HFP ferroelectric film. S7, Constructing the Janus structure: The self-supporting porous PVDF-HFP ferroelectric film is uniformly spread on the glass substrate, and the conductive and antibacterial MXene@Ag composite fabric obtained in step S3 is flatly covered on it. After the solvent has completely evaporated, it is peeled off from the substrate to obtain a Janus structure fabric with a conductive and antibacterial MXene@Ag layer on one side and a porous PVDF-HFP ferroelectric layer on the other side. S8, Drying and Finishing: Vacuum drying of the Janus structure fabric obtained in S7 to enhance interlayer bonding and stability.

[0009] As described above and in any possible implementation, a further implementation is provided, wherein S1 specifically comprises: adding 1 mg·mL⁻ 1 The MXene dispersion was mixed with 10 mM silver nitrate solution at a volume ratio of 1:1 to obtain the MXene / Ag⁺ composite solution.

[0010] In addition to the aspects and any possible implementations described above, a further implementation is provided, wherein S2 specifically involves: ultrasonically cleaning the cotton fabric in deionized water and anhydrous ethanol for 15 minutes each, and then drying it at 60 ℃ for later use.

[0011] In addition to the aspects and any possible implementations described above, a further implementation is provided, wherein S3 specifically comprises: immersing the pretreated cotton fabric in the MXene / Ag⁺ composite solution of step S1, stirring at 50 rpm for 30 min at room temperature, so that Ag⁺ is adsorbed onto the MXene sheets and fiber surface; removing the fabric and drying it at 60 ℃ for 1 h, and uniformly spraying an ascorbic acid (VC) aqueous solution for in-situ reduction, followed by washing with deionized water and drying at 60 ℃ to obtain a conductive and antibacterial MXene@Ag composite fabric. The concentration of ascorbic acid used for in-situ reduction is 5 mM, the reaction time is 25-35 min, and the preferred adsorption stirring speed is 50±10 rpm.

[0012] In addition to the aspects and any possible implementations described above, a further implementation is provided, wherein S4 specifically involves: adding 15 wt% of PVDF-HFP powder to N,N-dimethylacetamide and stirring at room temperature until uniform and transparent to obtain a PVDF-HFP precursor solution.

[0013] In addition to the aspects and any possible implementations described above, a further implementation is provided, wherein S5 specifically comprises: adding hexagonal boron nitride (h-BN) nanoparticles to the PVDF-HFP precursor solution and dispersing them uniformly; then adding tetrabutylammonium hexafluorophosphate (TBAHP) to regulate the microporous structure and ferroelectric phase content of the membrane; the amount of h-BN added is 0.1-1.0 wt%, and the amount of TBAHP added is preferably 2-9 wt%, to promote the formation of micro / nano porous structures and increase the ferroelectric β phase content.

[0014] In addition to the aspects and any possible implementations described above, a further implementation is provided, wherein S6 specifically involves: stirring the mixed solution in a water bath at 80 ℃ for 2 h and ultrasonically degassing for 30 min; drop-coating the precursor liquid onto a clean glass substrate, allowing it to dry naturally at room temperature, and then slowly peeling it off to obtain a self-supporting porous PVDF-HFP ferroelectric film.

[0015] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the room temperature drying time after drop-coating the film in S6 is 8-24 h, and the peeling speed is controlled at 5-20 mm·min-1 to avoid film cracking.

[0016] In addition to the aspects described above and any possible implementation, a further implementation is provided in which the vacuum drying temperature in S8 is 55-65 °C, the time is 6-10 h, and the vacuum degree is preferably ≤−0.08 MPa.

[0017] In accordance with the aspects described above and any possible implementation, a Janus-structured functional fabric based on a flexible porous PVDF-HFP ferroelectric film is further provided. This fabric is prepared using the aforementioned method. The Janus-structured functional fabric comprises a bilayer heterogeneous structure consisting of an MXene@Ag conductive antibacterial layer and a porous PVDF-HFP@BN-TBAHP ferroelectric layer. It possesses comprehensive properties including hydrophilicity on one side and hydrophobicity on the other, high thermal stability, mechanical flexibility, and long-term antibacterial capability. The Janus-structured functional fabric has a thermal decomposition initiation temperature ≥350 ℃, a maximum weight loss rate peak temperature ≥430 ℃, and maintains macroscopic morphological stability at 180 ℃. Its maximum tensile strength is 3.5–4.2 MPa, and its elongation at break is 50–55%. It maintains structural integrity under repeated bending and winding conditions. The Janus-structured functional fabric exhibits antibacterial rates of not less than 99.42%, 99.46%, and 98.87% against Escherichia coli, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus, respectively.

[0018] Compared with the prior art, the present invention can achieve the following technical effects: 1. The preparation method of “MXene@Ag composite fabric construction - porous PVDF-HFP membrane preparation - Janus structure composite” is simple in process steps, does not require vacuum or complex equipment conditions, and can realize low-cost and scalable flexible fabric functionalization, which is suitable for large-area continuous preparation and practical production applications.

[0019] 2. By introducing MXene nanosheets and silver nanoparticles to form a lamellar-particle composite structure on the fabric surface, the surface roughness and interfacial bonding strength of the fiber were significantly improved, enhancing the structural integrity and functional synergy of the material. SEM and XRD analysis results showed that the composite structure was stable and dense, with clear MXene(002) and Ag(111) crystal plane features, indicating that the conductive and antibacterial active layer was successfully constructed and tightly bonded to the substrate.

[0020] 3. This Janus fabric achieves dual optimization of thermal properties and structural stability by introducing h-BN and TBAHP to construct a porous ferroelectric layer. Thermogravimetric analysis results show that the initial decomposition temperature of the Janus composite film can reach 380°C, and the peak of the maximum decomposition rate reaches 437°C, which is significantly higher than that of single-layer PVDF-HFP or MXene fabrics, indicating that it has excellent thermal inertia and morphological stability under high temperature conditions.

[0021] 4. Through a dual-layer synergistic structural design, the fabric maintains both good flexibility and high mechanical strength. Tensile test results show that the maximum tensile strength of this Janus membrane is approximately 4.00 MPa, and the elongation at break reaches 52.6%. Compared with single-layer membranes, it achieves a balance between strength and ductility, indicating that it can maintain structural integrity under repeated bending, winding, and complex deformation, making it suitable for wearable and flexible electronics applications.

[0022] 5. This fabric exhibits a significant difference in interfacial wetting polarity. One side is a hydrophobic PVDF-HFP@BN-T layer with an initial contact angle of approximately 116° that remains stable within 15 seconds. The other side is a hydrophilic MXene@Ag conductive layer, which allows droplets to be completely absorbed within seconds. This structure enables unidirectional droplet penetration and rapid drainage, resulting in excellent waterproof, stain-resistant, and moisture-permeable control properties.

[0023] 6. The results showed that the prepared MXene@Ag composite layer had significant intrinsic antibacterial ability, with inhibition rates of 99.42%, 99.46%, and 98.87% against E. coli, S. aureus, and MRSA, respectively. The continuous release of silver ions and the high conductivity of MXene synergistically disrupted the bacterial cell membrane structure, thereby achieving a stable and long-lasting antibacterial protective effect.

[0024] 7. The Janus fabric exhibited excellent sensitivity and repeatability in human motion sensing tests. The sensing unit can stably capture various mechanical signals such as finger bending, head nodding, knee joint movement, and elbow bending. The voltage response amplitude is clear and the waveform is regular, which can effectively distinguish different motion states. It has good recognition and response consistency, and has broad application potential in health monitoring and human-computer interaction.

[0025] Of course, any product implementing this invention does not necessarily need to achieve all of the technical effects described above at the same time. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments 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.

[0027] Figure 1 This is a flowchart illustrating the preparation of multifunctional Janus fabrics in an embodiment of the present invention.

[0028] Figure 2Morphology and composition tests of the hydrophobic and hydrophilic surfaces of the Janus fabric in this embodiment of the invention: (a.) Original cotton fabric; (b.) MXene@Ag coated cotton fibers, magnification of 2k×; (c.) XRD of the fabric surface; (d.) Pure PVDF-HFP; (e.) PVDF-HFP@BN-TBAHP, magnification of 1k×; (f.) XRD of the PVDF-HFP surface.

[0029] Figure 3 Comparison of thermal properties of PV, PV-BN@TBAHP, F-MXene@Ag and Janus membranes: (a) TGA curves of each membrane sample under nitrogen atmosphere; (b) DTG curves; (c) DSC curves; (d) Images of membrane samples after treatment at different temperatures.

[0030] Figure 4 Mechanical properties of the Janus membrane in this embodiment of the invention: (a) Stress-strain curves of films with different components; (b) Comparison of breaking strength and elongation at break; Flexibility of the Janus membrane: (d) Bending; (e) Winding.

[0031] Figure 5 Comparison of wetting properties of different membranes in the embodiments of the present invention: (a) Changes in WCA time on the hydrophilic / hydrophobic sides of the Janus membrane; (b) Comparison of water contact angles of PVDF-HFP, PV-BN and PV-BN-T membranes; (c) Dynamic contact angle diagrams of water droplets on the surfaces of raw cotton fibers, F-MXene-modified cotton fabric and F-MXene@Ag-modified cotton fabric.

[0032] Figure 6 This image shows the culture of two bacteria, Escherichia coli and Staphylococcus aureus, on the surface of the Janus fabric for antibacterial testing in this embodiment of the invention.

[0033] Figure 7 The voltage response signals of Janus fabric used for motion monitoring of different human body parts in this embodiment of the invention are: (a) finger bending; (b) head nodding; (c) knee bending (walking and running); (d) elbow bending. Detailed Implementation

[0034] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0035] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. 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.

[0036] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0037] like Figure 1 As shown, this invention provides a method for preparing a Janus-structured functional fabric based on a flexible porous PVDF-HFP ferroelectric film, the preparation method comprising the following steps: S1: Prepare MXene / Ag⁺ composite solution by adding 1 mg·mL⁻ 1 The MXene dispersion was mixed with 10 mM silver nitrate solution at a volume ratio of 1:1 to obtain an MXene / Ag⁺ composite solution; S2: Cotton fabric pretreatment: Place the cotton fabric in deionized water and anhydrous ethanol in sequence for ultrasonic cleaning for 15 minutes each, and dry at 60 ℃ for later use. S3: Construct the MXene@Ag composite conductive layer. Immerse the pretreated cotton fabric in the composite solution of step S1 and stir at 50 rpm for 30 min at room temperature to allow Ag⁺ to be adsorbed onto the MXene sheets and fiber surface. After removal, dry at 60 ℃ for 1 h and uniformly spray with 5 mM ascorbic acid (VC) aqueous solution for in-situ reduction for 30 min. Then wash with deionized water and dry at 60 ℃ to obtain conductive and antibacterial MXene@Ag composite fabric. S4: Prepare PVDF-HFP precursor solution by adding 15 wt% PVDF-HFP powder to N,N-dimethylacetamide (DMAc) and stirring at room temperature until homogeneous and transparent; S5: Add filler and pore structure inducer. Add 0.5 wt% hexagonal boron nitride (h-BN) nanoparticles to the solution in step S4 and disperse them evenly; then add 0.5–12 wt% tetrabutylammonium hexafluorophosphate (TBAHP) to regulate the micropore structure and ferroelectric phase content of the membrane. S6: Degassing and film formation: The mixed solution was stirred in an 80 ℃ water bath for 2 h and ultrasonically degassed for 30 min; the precursor solution was drop-coated onto a clean glass substrate, allowed to dry naturally at room temperature, and then slowly peeled off to obtain a self-supporting porous PVDF-HFP ferroelectric film. S7: Construct the Janus structure by uniformly spreading the h-BN / TBAHP-doped PVDF-HFP solution on a glass substrate, and then flatly covering it with the MXene@Ag composite cotton fabric obtained in step S3. After the solvent has completely evaporated, the fabric is peeled off from the substrate to obtain a Janus structure fabric with a conductive and antibacterial MXene@Ag layer on one side and a porous PVDF-HFP ferroelectric layer on the other side. S8: Drying and Finished Product Processing: The resulting composite fabric is vacuum dried at 60 °C for 8 h to enhance interlayer bonding and stability.

[0038] In step S3, the concentration of ascorbic acid used for in-situ reduction is 5 mM, the reaction time is 25-35 min, and the preferred adsorption stirring speed is 50±10 rpm.

[0039] In step S5, the amount of h-BN added is 0.1-1.0 wt%, and the amount of TBAHP added is preferably 2-9 wt%, in order to promote the formation of micro / nano porous structures and increase the content of ferroelectric β phase.

[0040] In step S6, the room temperature drying time after drop coating is 8-24 h, and the peeling speed is controlled at 5-20 mm·min-1 to avoid film cracking.

[0041] The vacuum drying temperature in step S8 is 55-65 ℃, the time is 6-10 h, and the vacuum degree is preferably ≤−0.08MPa.

[0042] The fabrics with Janus structure have different interfacial wetting polarities: one side of PVDF-HFP@BN-TBAHP is hydrophobic with an initial water contact angle ≥115°; the other side of MXene@Ag is hydrophilic, and water droplets diffuse and absorb within 5 s.

[0043] The obtained Janus structure fabric has a thermal decomposition initiation temperature ≥350 ℃, a maximum weight loss rate peak temperature ≥430 ℃, and maintains macroscopic morphological stability at 180 ℃.

[0044] The resulting Janus structure fabric has a maximum tensile strength of 3.5–4.2 MPa and an elongation at break of 50–55%, and can maintain structural integrity under repeated bending and winding conditions.

[0045] The Janus structure fabric obtained has an antibacterial rate of no less than 99.42%, 99.46% and 98.87% against Escherichia coli, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus, respectively.

[0046] This invention also provides a Janus-structured functional fabric based on a flexible porous PVDF-HFP ferroelectric film. This fabric consists of a bilayer heterogeneous structure composed of an MXene@Ag conductive antibacterial layer and a porous PVDF-HFP@BN-TBAHP ferroelectric layer. It possesses comprehensive properties including hydrophilicity on one side and hydrophobicity on the other, high thermal stability, mechanical flexibility, and long-term antibacterial capability. Figure 2 The figures shown are the morphology and composition test results of the hydrophobic and hydrophilic surfaces of the Janus fabric, where (a.) the original cotton fabric; (b) MXene@Ag coated cotton fibers, magnification of 2k×; (c) XRD of the fabric surface; (d) pure PVDF-HFP; (e) PVDF-HFP@BN-TBAHP, magnification of 1k×; (f) XRD of the PVDF-HFP surface.

[0047] Example 1: This embodiment also provides a method for testing durability under complex environments, which is used to test the durability performance of Jnaus fabric prepared by the above method. The testing method generally includes the following steps: P1. Thermal Stability Test: Different prepared samples were cut into small pieces of approximately 5 mg and placed in crucibles for testing. A thermogravimetric analyzer (TGA) was used to heat the samples within a temperature range of 20-800°C under a nitrogen atmosphere (flow rate 50 mL / min) at a heating rate of 10°C / min, while simultaneously recording the mass change of the samples. Differential scanning calorimetry (DSC) was used to perform heat flow tests under the same atmospheric conditions, with a temperature range of 25-300°C and a heating rate of 10°C / min, to analyze the thermal response characteristics of the materials. In addition, different film materials were heated in a constant temperature environment of 25-180°C for 30 min, and their morphological changes were observed and recorded.

[0048] P2. Wetting performance test: The hydrophobicity of the textile was tested using a JC2000DM contact angle tester. Five different surface points were measured at room temperature, and the WCA of the sample was recorded. The water droplet volume was 4 μL.

[0049] P3. Mechanical property testing: Select textiles of relatively uniform thickness and cut them into strips of 40mm × 5mm. Each sample group was tested 5 times. Then, the stress and elongation at break of the textiles were tested using a tensile testing machine with a pre-tension of 0.2N, a tensile rate of 5mm / min, a spacing of 20mm, a gravity clamp of 0.5, an ambient temperature of approximately 25℃, and a relative humidity of approximately 50%. The tensile stress and tensile strain of the samples were recorded.

[0050] P4. Antibacterial Performance Test: First, agar and Luria-Bertani (LB) broth were prepared in a specific ratio and cultured overnight. The original bacterial solution was diluted to 10⁸ CFU / ml with phosphate-buffered saline (PBS). Subsequently, 100 μL of the bacterial suspension was dispersed on a carbon cloth surface. After serial dilution, 100 μL of the bacterial solution was gently and evenly dispersed on a solid agar plate. Finally, all samples were transferred to a 37°C incubator for 12–16 hours, photographed, and colony counted. The CFU counts of the experimental group and the control group were compared to calculate the inhibition rate. Inhibition rate = (Control group - Experimental group) / Control group × 100% P5. Mechanical Sensing Performance Test: First, the prepared Janus functional fabric sample was cut into square sheets of approximately 3cm × 3cm to ensure test consistency. One side of the sample was a conductive MXene@Ag layer, and the other side was a flexible porous PVDF-HFP ferroelectric film layer. A copper foil was used to connect the conductive layer to a high-impedance electrometer (Keithley 6514), with the other end grounded as a reference electrode. Subsequently, the sample was fixed to the outside of a flexible support or different parts of the human body (such as fingers, elbows, knees, neck, etc.), ensuring the ferroelectric film surface faced outwards to respond to mechanical deformation. The test skin surface was pre-cleaned with alcohol wipes and kept dry to reduce sweat interference. During the test, periodic mechanical stimulation was applied by controlling the frequency and amplitude of human movements: finger bending angle approximately 60°, frequency 1-3Hz; head nodding angle approximately 30°, frequency 1-2Hz; knee bending simulating walking and jogging movements, frequency 1.5-3Hz; elbow bending angle approximately 90°, frequency 1-2Hz. Each action lasted 30 seconds. The thermal performance comparison results of PV, PV-BN@TBAHP, F-MXene@Ag, and Janus films are as follows: Figure 3 As shown in the figure, (a) TGA curves of each membrane sample under nitrogen atmosphere; (b) DTG curves; (c) DSC curves; (d) images of membrane samples treated at different temperatures, the mechanical properties of the Janus membrane are presented. Figure 4 As shown in the figure, (a) stress-strain curves of films with different compositions; (b) comparison of breaking strength and elongation at break; flexibility of the Janus film: (d) bending; (e) winding. Simultaneously, the wettability of different films was compared, and the results are as follows: Figure 5 As shown in the figure: (a) WCA time variation on the hydrophilic / hydrophobic sides of the Janus membrane; (b) Comparison of water contact angles of PVDF-HFP, PV-BN and PV-BN-T membranes; (c) Dynamic contact angle diagram of water droplets on the surfaces of raw cotton fibers, F-MXene-modified cotton fabric and F-MXene@Ag-modified cotton fabric.

[0051] The antibacterial test results of the Janus fabric of this invention are as follows: Figure 6 As shown in the figure, the culture results of two bacteria, Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), on the surface of Janus fabric can be seen. The voltage response signals of the Janus fabric used in this invention for motion monitoring of different human body parts are shown in the figure. Figure 7 As shown in the figure: (a) bent fingers; (b) nodding; (c) bent knees (walking and running); (d) bent elbows.

[0052] This invention utilizes a Janus-structured functional fabric material that simultaneously possesses superhydrophobic / superhydrophilic switchable wettability, high thermal stability, mechanical flexibility, and antibacterial capabilities. This material is achieved by sequentially constructing an MXene@Ag composite conductive antibacterial layer and a porous PVDF-HFP@BN-TBAHP ferroelectric layer, forming a stable, bonded bilayer heterostructure at the interface. This material not only enables efficient thermal regulation and humidity management in complex environments but also serves as a structural substrate and sensing platform for flexible wearable electronic devices. It exhibits significant advantages such as simple structure, scalable fabrication, high functional integration, and strong environmental adaptability.

[0053] The foregoing has provided a detailed description of a Janus-structured functional fabric based on a flexible porous PVDF-HFP ferroelectric film and its preparation method, as provided in the embodiments of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this application; furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

[0054] Certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The terms "comprising" and "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising / including but not limited to". "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error. The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of illustrating the general principles of this application and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0055] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0056] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0057] The foregoing description illustrates and describes several preferred embodiments of this application. However, as previously stated, it should be understood that this application is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the application concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this application should be within the protection scope of the appended claims.

Claims

1. A method for preparing Janus-structured functional fabrics based on flexible porous PVDF-HFP ferroelectric films, characterized in that, The preparation method includes the following steps: S1, Preparation of MXene / Ag⁺ composite solution: Mix MXene dispersion and silver nitrate solution at a volume ratio of 1:1 to obtain MXene / Ag⁺ composite solution; S2, cotton fabric pretreatment, the cotton fabric is placed in deionized water and anhydrous ethanol in sequence for ultrasonic cleaning and drying for later use. S3, Constructing the MXene@Ag Composite Conductive Layer: Immerse the pretreated cotton fabric in the MXene / Ag⁺ composite solution, stir to allow Ag⁺ to be adsorbed onto the MXene flakes and fiber surface, uniformly spray with ascorbic acid aqueous solution for in-situ reduction, then wash with deionized water and dry to obtain conductive and antibacterial MXene@Ag composite fabric. S4, Preparation of PVDF-HFP precursor solution: Add PVDF-HFP powder to N,N-dimethylacetamide and stir at room temperature until uniform and transparent to obtain PVDF-HFP precursor solution; S5, Add filler and pore structure inducer: Add hexagonal boron nitride nanoparticles to the PVDF-HFP precursor solution and disperse them evenly; then add 0.5–12 wt% of tetrabutylammonium hexafluorophosphate to regulate the micropore structure and ferroelectric phase content of the membrane to obtain a mixed solution; S6, Degassing and Film Formation: The mixed solution is stirred in a water bath and ultrasonically degassed, then drop-coated onto a clean glass substrate. After natural drying at room temperature, it is slowly peeled off to obtain a self-supporting porous PVDF-HFP ferroelectric film. S7, Constructing the Janus structure: The self-supporting porous PVDF-HFP ferroelectric film is uniformly spread on the glass substrate, and the conductive and antibacterial MXene@Ag composite fabric obtained in step S3 is flatly covered on it. After the solvent has completely evaporated, it is peeled off from the substrate to obtain a Janus structure fabric with a conductive and antibacterial MXene@Ag layer on one side and a porous PVDF-HFP ferroelectric layer on the other side. S8, Drying and Finished Product Processing: Vacuum drying of the Janus structure fabric obtained in S7.

2. The preparation method according to claim 1, characterized in that, Specifically, S1 involves: adding 1 mg·mL⁻ 1 The MXene dispersion was mixed with 10 mM silver nitrate solution at a volume ratio of 1:1 to obtain the MXene / Ag⁺ composite solution.

3. The preparation method according to claim 1, characterized in that, S2 specifically involves: placing the cotton fabric in deionized water and anhydrous ethanol in sequence for ultrasonic cleaning for 15 minutes each, and then drying it at 60 ℃ for later use.

4. The preparation method according to claim 1, characterized in that, S3 specifically involves immersing the pretreated cotton fabric in the MXene / Ag⁺ composite solution from step S1, stirring at 50 rpm for 30 min at room temperature to allow Ag⁺ to adsorb onto the MXene sheets and fiber surface; removing the fabric and drying it at 60 ℃ for 1 h, then uniformly spraying it with an ascorbic acid (VC) aqueous solution for in-situ reduction, followed by washing with deionized water and drying at 60 ℃ to obtain a conductive and antibacterial MXene@Ag composite fabric. The concentration of ascorbic acid used for in-situ reduction is 5 mM, the reaction time is 25-35 min, and the preferred adsorption stirring speed is 50±10 rpm.

5. The preparation method according to claim 1, characterized in that, S4 specifically involves adding 15 wt% PVDF-HFP powder to N,N-dimethylacetamide and stirring at room temperature until homogeneous and transparent to obtain a PVDF-HFP precursor solution.

6. The preparation method according to claim 1, characterized in that, S5 specifically involves: adding hexagonal boron nitride (h-BN) nanoparticles to the PVDF-HFP precursor solution and dispersing them evenly; then adding tetrabutylammonium hexafluorophosphate (TBAHP) to regulate the microporous structure and ferroelectric phase content of the membrane; the amount of h-BN added is 0.1-1.0 wt%, and the amount of TBAHP added is 2-9 wt%, to promote the formation of micro / nano porous structures and increase the ferroelectric β phase content.

7. The preparation method according to claim 1, characterized in that, S6 specifically involves: stirring the mixed solution in an 80°C water bath for 2 hours and then ultrasonically degassing for 30 minutes; drop-coating the precursor solution onto a clean glass substrate, allowing it to dry naturally at room temperature, and then slowly peeling it off to obtain a self-supporting porous PVDF-HFP ferroelectric film.

8. The preparation method according to claim 1, characterized in that, The room temperature drying time after drop coating in S6 is 8-24 h, and the peeling speed is controlled at 5-20 mm·min-1 to avoid film cracking.

9. The preparation method according to claim 1, characterized in that, The vacuum drying process in S8 is carried out at a temperature of 55-65 ℃ for 6-10 h, with a vacuum degree of ≤−0.08 MPa.

10. A Janus-structured functional fabric based on a flexible porous PVDF-HFP ferroelectric film, prepared by the preparation method described in any one of claims 1-9, characterized in that, The Janus structural functional fabric is composed of a bilayer heterogeneous structure consisting of an MXene@Ag conductive antibacterial layer and a porous PVDF-HFP@BN-TBAHP ferroelectric layer. It possesses comprehensive properties including hydrophilicity on one side and hydrophobicity on the other, high thermal stability, mechanical flexibility, and long-term antibacterial capability. The Janus structural functional fabric has a thermal decomposition initiation temperature ≥350 ℃, a maximum weight loss rate peak temperature ≥430 ℃, and maintains macroscopic morphological stability at 180 ℃. Its maximum tensile strength is 3.5–4.2 MPa, and its elongation at break is 50–55%. It maintains structural integrity under repeated bending and winding conditions. The Janus structural functional fabric exhibits antibacterial rates of no less than 99.42%, 99.46%, and 98.87% against Escherichia coli, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus, respectively.

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