Layered flexible nano flame-retardant coating with ion-electron synergistic thermoelectric response, preparation method and application

Abstract

The application discloses a layered flexible nano flame-retardant coating with ion-electron synergistic thermoelectric response, a preparation method and application, and relates to the technical field of flame-retardant coatings.

Description

Technical Field

[0001] This invention relates to the field of flame-retardant coatings, and in particular to a layered flexible nano flame-retardant coating with ion-electron synergistic thermoelectric response, its preparation method, and its application. Background Technology

[0002] Fire safety has always been a challenging issue in the electrical field. Especially in recent years, with the rise of flexible electrical equipment, the increasing complexity of electrical materials, the thinning of insulation layers, and the more frequent deformation have led to a significant increase in electrical failure rates, further exacerbating the electrical fire safety situation. Furthermore, the widespread use of flammable polymer materials in flexible electrical equipment causes electrical fires to develop extremely rapidly, with only a few minutes required from ignition to flashover. However, current mainstream smoke or heat alarms typically only respond about two minutes after ignition, failing to provide early warning and leaving extremely limited time for escape and rescue. Therefore, improving the fire safety of electrical materials requires not only enhancing their flame-retardant properties but also finding a more efficient fire warning method.

[0003] Thermoelectric (TE) materials have broad application prospects in temperature sensing and fire early warning (CN120329768B, CN117222295A) because they can output voltage signals by directly converting heat energy into electrical energy without relying on an external power source, and the voltage signal value has a linear functional relationship with temperature. More importantly, this functional relationship also applies to lower temperature ranges (≤ 200℃), so thermoelectric materials can effectively monitor the temperature rise process during the fire incubation period, truly achieving early fire warning. In addition, the regular electrical signal response mechanism also facilitates the integration of thermoelectric-based sensing materials into IoT-based intelligent fire protection systems. Using IoT technology, temperature sensing signals can be remotely transmitted to mobile devices in real time, and warning signals can be immediately issued to users and fire organizations when a preset danger temperature is reached, nipping fires in the bud and significantly improving the fire safety of electrical equipment. However, accurate real-time remote temperature sensing places stringent demands on the sensitivity and stability of the voltage-temperature function relationship of thermoelectric materials, which existing flexible thermoelectric materials (including electronic thermoelectric materials (e-TE) and ionic thermoelectric materials (i-TE)) struggle to meet. Traditional e-TEs possess high conductivity and fast carrier transport speed; however, their Seebeck coefficient is generally low, affecting the reliability and accuracy of the sensing signal. Therefore, electronic thermoelectric sensing materials often require multiple P-type and N-type units to be alternately connected in series to achieve a sufficiently large output voltage for accurate temperature sensing, which is extremely inconvenient in application. In contrast, i-TEs have attracted widespread attention in the field of temperature sensing due to their Seebeck coefficient, which is 1-2 orders of magnitude higher than that of e-TEs. However, i-TEs have low conductivity and slow carrier transport speed, resulting in low thermoelectric response sensitivity and large signal fluctuations. It is easy to see that there is a strong complementary relationship between e-TE and i-TE; their synergy is considered a new solution for achieving accurate, sensitive, and stable temperature sensing. However, due to the significant differences in the transport mechanisms and media between the two types of charge carriers, achieving ion-electron synergy in thermoelectric materials remains a major challenge. Therefore, designing a layered flexible nanofiber retardant coating with ion-electron synergistic thermoelectric response has important practical application value in fire early warning. Summary of the Invention

[0004] This invention aims to provide a layered flexible nano flame-retardant coating with ion-electron synergistic thermoelectric response, its preparation method, and its application, thereby solving the technical problems of existing thermoelectric materials in fire early warning that cannot achieve accurate, sensitive, and stable temperature sensing, while also exhibiting poor flame-retardant effects.

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: a method for preparing a layered flexible nano flame-retardant coating with ion-electron synergistic thermoelectric response, characterized in that: a conductive polymer solution and a layered material with thermoelectric function are uniformly dispersed by ultrasonication, and mixed with an ion solution A at a mass fraction ratio of 1:1:0.1 to 1:1:0.5 to obtain a coating with ion-electron synergistic thermoelectric response; the coating is applied to the surface of a flammable material in a flexible electronic device, and after drying, a layered flexible nano flame-retardant coating with ion-electron synergistic thermoelectric response is obtained;

[0006] The conductive polymer solution is prepared through the following steps.

[0007] Step S1: Prepare a conductive polymer solution.

[0008] Step S1.1: Add sodium polystyrene sulfonate solution, initiator A and catalyst A to solvent A with a pH of 4-7, and disperse them evenly in the solvent to obtain mixed solution A;

[0009] Step S1.2: Adjust the reaction temperature to 0~50℃, add organic thermoelectric monomer A to mixed solution A, and carry out the mixed reaction for 8~24h to obtain reaction solution A;

[0010] Step S1.3: After washing the reaction solution A by centrifugation 3-6 times with solvent B, dissolve it in deionized water and treat it in an ultrasonic homogenizer for 20-120 minutes to obtain a conductive polymer solution.

[0011] The layered material with thermoelectric properties is prepared through the following steps.

[0012] Step S2: Prepare a layered structure with thermoelectric function.

[0013] Step S2.1: By ultrasonic treatment, the layered material is uniformly dispersed in solvent C with a pH of 4-7, morphology guiding agent A is added, and ultrasonic treatment is continued to make it uniformly loaded on the surface of the layered material to obtain reaction solution B.

[0014] Step S2.2: Add initiator B and thermoelectric monomer B to reaction solution B, and react in a water bath at 30~80℃ for 3~12h to obtain reaction solution C;

[0015] Step S2.3: After washing the reaction solution C by centrifugation 3-6 times with solvent D, dissolve it in deionized water to obtain a layered material with thermoelectric function.

[0016] In a further technical solution, in step S1.1, the mass ratio of sodium polystyrene sulfonate to thermoelectric monomer A is 1:3 to 10:1, the mass ratio of initiator A to thermoelectric monomer A is 1:50 to 2:1, and the mass ratio of catalyst A to thermoelectric monomer A is 1:100 to 1:10.

[0017] In a further technical solution, the mass ratio of morphology guiding agent A to layered material in step S2.1 is 1:3~4:1, the mass ratio of initiator B to layered material in step S2.2 is 1:50~3:1, and the mass ratio of thermoelectric monomer B to layered material is 1:10~3:1.

[0018] In a further technical solution, the ionic solution A is at least one of 1-butyl-3-methylimidazolium octyl sulfate, 1-octyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium tetrafluoroborate, or trihexyltetradecylphosphonium.

[0019] In a further technical solution, solvent A is at least one selected from deionized water, ethanol, methanol, isopropanol, n-butanol, and acetone;

[0020] Solvent B is at least one of deionized water, ethanol, methanol, isopropanol, n-butanol, and acetone;

[0021] The initiator A is at least one of potassium persulfate, ammonium persulfate, azobisisobutyronitrile, benzoyl peroxide, azobisisobutyramidine hydrochloride, and tert-butanol peroxide;

[0022] The catalyst A is at least one of ferric chloride, potassium persulfate, ammonium persulfate, aluminum trichloride, and tin tetrachloride;

[0023] The thermoelectric monomer A is at least one of 3,4-ethylenedioxythiophene, aniline, pyrrole, and carbazole.

[0024] A further technical solution is that the layered material is graphene, , and At least one of them;

[0025] The morphology guiding agent A is at least one of polyvinylpyrrolidone, polyethylene glycol, polyethyleneimine, hexadecyltrimethylammonium bromide, and sodium dodecyl sulfate;

[0026] The initiator B is one or more of potassium persulfate, ammonium persulfate, azobisisobutyronitrile, benzoyl peroxide, and tert-butanol peroxide; the thermoelectric monomer B is at least one of thiophene, 3-hexylthiophene, 3,4-ethylenedioxythiophene, aniline, pyrrole, and carbazole.

[0027] The solvent C is at least one selected from deionized water, ethanol, methanol, isopropanol, n-butanol, and acetone.

[0028] The solvent D is at least one of deionized water, ethanol, methanol, isopropanol, n-butanol, and acetone.

[0029] A further technical solution is a layered flexible nano flame-retardant coating with ion-electron synergistic thermoelectric response, which is prepared by the aforementioned method for preparing a layered flexible nano flame-retardant coating with ion-electron synergistic thermoelectric response.

[0030] A further technical solution is the application of a layered flexible nano flame-retardant coating with ion-electron synergistic thermoelectric response. This coating is applied to the surface of a flammable material in a flexible electronic device. The coating method is one of spraying, dripping, or dipping. The flammable material in the flexible electronic device is a polyester film or polyurethane foam.

[0031] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0032] 1. When the coating is exposed to high temperatures, cations in the ionic solution migrate from high to low temperatures, creating ionic potentials and ionic electric fields. Simultaneously, internal electrons are driven by thermal and electric forces to migrate from high to low temperatures, thus creating electronic potentials. The ionic and electronic potentials together form the coating's thermal output voltage. The higher the temperature, the greater the voltage generated by the coating, and the relationship between temperature and voltage is strongly linear. Therefore, this relationship allows for precise detection of the ambient temperature of the coating.

[0033] 2. Due to the excellent thermal stability and layered barrier properties of the layered material, when exposed to high temperatures, it undergoes a synergistic carbonization reaction with the conductive polymer, causing the nanosheets to bond tightly together and forming a dense, porous barrier layer. This allows the coating to exhibit excellent flame retardant properties and also ensures the continuous and stable output of thermoelectric signals in a combustion environment.

[0034] 3. This invention, through innovative material design, successfully achieves a synergistic thermoelectric response between ions and electron carriers. This allows the coating to combine the advantages of rapid response and high conductivity of electronic materials with the high sensitivity (high Seebeck coefficient) of ionic materials. The resulting sensing signal is not only strong and fast-responding, but also exhibits low fluctuation and high reliability, providing a precise and stable data foundation for subsequent intelligent judgment.

[0035] 4. The regular electrical signals generated by the coating of this invention are natural sensing signals that do not require an external power source, making them extremely convenient to connect to the Internet of Things (IoT) system. Through circuit connection and wireless transmission modules, remote real-time monitoring and cloud analysis of temperature data can be achieved, and warnings can be automatically issued to users and fire protection platforms when preset risk thresholds are reached. This realizes a closed loop of "real-time monitoring - intelligent early warning - active protection," greatly improving the intrinsic safety level and active fire protection capabilities of electrical equipment. Attached Figure Description

[0036] Figure 1 The figures show the thermal output voltage curves and temperature-voltage fitting curves at different temperatures ranging from 50 to 300°C in Embodiment 1 of the present invention.

[0037] Figure 2 This is a graph showing the time and output voltage of 100 cycles of alternating hot and cold temperatures between room temperature and 200 degrees Celsius in Embodiment 1 of the present invention.

[0038] Figure 3 This is a scanning electron microscope (SEM) image of the cross-section of the coating in Example 1 of the present invention. The nano-coating exhibits a layered nanosheet stacked structure, which has excellent thermal stability and layered barrier properties. When exposed to high temperatures, it undergoes a synergistic carbonization reaction with the conductive polymer, causing the nanosheets to bond tightly together and form a dense, porous barrier layer, enabling the coating to exert a good flame-retardant effect.

[0039] Figure 4 The images shown are screenshots from a video of the vertical combustion of a coated PET polyester film and an uncoated PET polyester film obtained in Example 1 of this invention.

[0040] Figure 5 This is a screenshot from a video showing the coating obtained in Embodiment 1 of the present invention used for remote temperature sensing fire early warning. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer and more complete, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Based on the content disclosed in this invention, any modifications, equivalent substitutions, or improvements made by those skilled in the art without departing from the principles and core design concepts of this invention should be included within the scope of protection of this invention.

[0042] Unless otherwise explicitly stated, the reagents, materials, and testing instruments used in the embodiments of this invention are all products that are conventional in the art or available through commercial channels. The polyester film mentioned herein is PET, and the polyurethane foam is PU.

[0043] Example 1: A conductive polymer solution and a layered material with thermoelectric properties were uniformly dispersed by ultrasonication.

[0044] (1) Preparation of a layered material with thermoelectric function. 0.1 g of graphene powder was added to 100 mL of deionized water with pH 7 and dispersed thoroughly by ultrasonic stirring to form a uniform and stable graphene suspension. Then, 0.06 g of polyvinylpyrrolidone was added to the suspension and ultrasonic treatment was continued to make polyvinylpyrrolidone uniformly coat the graphene surface. Next, 0.3 g of potassium persulfate and 0.3 g of thermoelectric monomer 3,4-ethylenedioxythiophene were added in sequence, and the mixture was transferred to a 50 °C water bath and reacted for 9 hours under magnetic stirring to obtain the product. After the reaction was completed, the product was centrifuged at 8000 rpm and washed three times with anhydrous ethanol to remove unreacted impurities. Finally, the obtained solid product was redispersed in an appropriate amount of deionized water to obtain a dispersion of the layered material with thermoelectric function.

[0045] (2) Preparation of conductive polymer solution. In 50 mL of deionized water with pH 7, 2 g of sodium polystyrene sulfonate solution, 0.3 g of ammonium persulfate, and 0.02 g of ferric chloride were added sequentially. The mixture was magnetically stirred for 30 minutes to ensure complete dissolution and homogeneity, yielding a homogeneous solution. The reaction system temperature was controlled within 30°C. 0.3 g of the thermoelectric monomer 3,4-ethylenedioxythiophene monomer was added to the homogeneous solution, and in-situ polymerization was carried out for 18 hours under continuous stirring to obtain the reaction product. The reaction product was centrifuged at 10,000 rpm, washed three times with methanol, and the resulting solid was redispersed in an appropriate amount of deionized water. The solid was then treated in an ultrasonic crusher at 400 W power for 10 minutes to finally obtain a homogeneous conductive polymer solution.

[0046] (3) A layered structure with thermoelectric function, a conductive polymer solution, and the ionic liquid 1-butyl-3-methylimidazolium octyl sulfate were mixed in a mass ratio of 1:1:0.1 to prepare an ion-electron synergistic thermoelectric responsive coating. The coating was then dip-coated onto a polyester (PET) film and dried in a 60°C oven for 10 minutes. The process was repeated six times. An ion-electron synergistic thermoelectric responsive coating with a thickness of approximately 10 μm was obtained. Fire warning and vertical combustion tests were performed on the coated samples, and the results are shown in Table 1.

[0047] Example 2

[0048] The difference between this embodiment and Example 1 is that: in step (1), 100 mL of deionized water with pH 7 is replaced with 100 mL of acetone with pH 7, the amount of graphene is increased from 0.1 g to 1 g, 0.06 g of polyvinylpyrrolidone is replaced with 0.5 g of polyethylene glycol, 0.3 g of potassium persulfate is replaced with 0.02 g of ammonium persulfate, 0.3 g of thermoelectric monomer 3,4-ethylenedioxythiophene is replaced with 0.1 g of 3-hexylthiophene, the reaction time is increased to 12 hours, and anhydrous ethanol washing is replaced with isopropanol washing. In step (2), 50 mL of deionized water with pH 7 was replaced with 50 mL of n-butanol with pH 4, the amount of sodium polystyrene sulfonate was reduced from 2 g to 0.5 g, the amount of ammonium persulfate was replaced with 0.1 g of azobisisobutyramidine hydrochloride, the amount of ferric chloride was replaced with 0.002 g of potassium persulfate, the amount of 3,4-ethylenedioxythiophene was reduced from 0.3 g to 0.1 g, the reaction temperature was increased to 50 °C, the reaction time was reduced to 8 hours, and methanol washing was replaced with washing with ethanol and deionized water. In step (3), the ionic liquid 1-butyl-3-methylimidazolium octyl sulfate was replaced with 1-octyl-3-methylimidazolium chloride, the drying temperature was reduced to 40 °C, and the reaction was repeated 10 times. The fire warning and vertical combustion test results are shown in Table 1.

[0049] Example 3

[0050] The difference between this embodiment and Embodiment 1 is that: in step (1), 100 mL of deionized water with pH 7 is replaced with 100 mL of ethanol with pH 6, and 0.1 g of graphene is replaced with 0.5 g of... In step (2), 0.06g of polyvinylpyrrolidone was increased to 0.2g, 0.3g of potassium persulfate was reduced to 0.2g, 0.3g of thermoelectric monomer 3,4-ethylenedioxythiophene was replaced with 0.2g of thiophene, the reaction temperature was increased to 80℃, the reaction time was reduced to 3 hours, and anhydrous ethanol washing was replaced with n-butanol washing. In step (3), 50mL of deionized water with pH 7 was replaced with 50mL of methanol with pH 6, 2g of sodium polystyrene sulfonate was increased to 3g, 0.3g of ammonium persulfate was replaced with 0.4g of tert-butanol peroxide, 0.02g of ferric chloride was replaced with 0.1g of ammonium persulfate, the content of 0.3g of 3,4-ethylenedioxythiophene was increased to 9g, the reaction temperature was reduced to 0℃, the reaction time was increased to 24 hours, and methanol washing was replaced with acetone washing. In step (3), the ionic liquid 1-butyl-3-methylimidazolium octyl sulfate was replaced with trihexytetradecylphosphonium. The results of the fire warning and vertical combustion tests are shown in Table 1.

[0051] Example 4

[0052] The difference between this embodiment and Example 1 is as follows: In step (1), 0.1g of graphene is replaced with 0.1g of Ti3AlC2, 0.06g of polyvinylpyrrolidone is replaced with 0.4g of polyethyleneimine, 0.3g of potassium persulfate is replaced with 0.1g of azobisisobutyronitrile, 0.3g of thermoelectric monomer 3,4-ethylenedioxythiophene is replaced with 0.2g of aniline, the reaction temperature is reduced to 30 degrees Celsius, and anhydrous ethanol washing is replaced with methanol washing followed by acetone washing. In step (2), 50mL of deionized water with pH 7 is replaced with 50mL of isopropanol with pH 7, the amount of sodium polystyrene sulfonate is reduced from 2g to 1g, 0.3g of ammonium persulfate is replaced with 0.2g of azobisisobutyronitrile hydrochloride, 0.02g of ferric chloride is replaced with 0.03g of tin tetrachloride, the content of 0.3g of 3,4-ethylenedioxythiophene is replaced with 0.3g of aniline, and methanol washing is replaced with n-butanol washing. In step (3), the ionic liquid 1-butyl-3-methylimidazolium octyl sulfate was replaced with 1-butyl-3-methylimidazolium tetrafluoroborate, and the mass fraction 1:1:0.1 was replaced with 1:1:0.5. The fire warning and vertical combustion test results are shown in Table 1.

[0053] Example 5

[0054] The difference between this embodiment and Embodiment 1 is that: in step (1), 100 mL of deionized water with pH 7 is replaced with 100 mL of isoacetone with pH 7, and 0.1 g of graphene is replaced with 0.8 g of... In step (2), 0.06g of polyvinylpyrrolidone was replaced with 0.2g of hexadecyltrimethylammonium bromide, 0.3g of potassium persulfate was replaced with 0.3g of benzoyl peroxide, and 0.3g of thermoelectric monomer 3,4-ethylenedioxythiophene was replaced with 0.2g of pyrrole. The reaction time was reduced to 6 hours, and anhydrous ethanol washing was replaced with isopropanol washing. In step (2), 50mL of deionized water with pH 7 was replaced with 50mL of n-butanol with pH 6, the amount of sodium polystyrene sulfonate was reduced from 2g to 0.2g, 0.3g of ammonium persulfate was replaced with 0.1g of benzoyl peroxide, 0.02g of ferric chloride was replaced with 0.01g of aluminum trichloride, and the content of 0.3g of 3,4-ethylenedioxythiophene was replaced with 0.1g of carbazole. The reaction time was increased to 24 hours. In step (3), the mass fraction 1:1:0.1 was replaced with 1:1:0.2, and the drying temperature was increased to 70℃. The results of the fire warning and vertical combustion tests are shown in Table 1.

[0055] Example 6

[0056] The difference between this embodiment and Embodiment 1 is that: in step (1), 100 mL of deionized water with pH 7 is replaced with 100 mL of n-butanol with pH 7, and 0.1 g of graphene is replaced with 0.8 g of... In step (2), 0.06g of polyvinylpyrrolidone was replaced with 0.2g of sodium dodecyl sulfate, 0.3g of potassium persulfate was replaced with 0.1g of tert-butanol peroxide, 0.3g of thermoelectric monomer 3,4-ethylenedioxythiophene was replaced with 0.25g of carbazole, and anhydrous ethanol washing was replaced with ethanol plus methanol washing. In step (2), 50mL of deionized water with pH 7 was replaced with 50mL of n-butanol with pH 6, the amount of sodium polystyrene sulfonate was reduced from 2g to 1g, 0.3g of ammonium persulfate was replaced with 0.2g of potassium persulfate, 0.02g of ferric chloride was replaced with 0.005g of azobisisobutyronitrile, the content of 0.3g of 3,4-ethylenedioxythiophene was replaced with 0.1g of pyrrole, and the reaction time was increased to 24 hours. In step (3), the mass fraction 1:1:0.1 was replaced with 1:1:0.3, and the drying temperature was increased to 70℃. The results of the fire warning and vertical combustion tests are shown in Table 1.

[0057] Example 7

[0058] The difference between this embodiment and Embodiment 1 is that the polyester (PET) film in step (3) is replaced with polyurethane (PU) foam. The fire warning and vertical combustion test results are shown in Table 1.

[0059] Example 8

[0060] The difference between this embodiment and Embodiment 2 is that the polyester (PET) film in step (3) is replaced with polyurethane (PU) foam. The fire warning and vertical combustion test results are shown in Table 1.

[0061] Example 9

[0062] The difference between this embodiment and embodiment 1 is that the dip coating method in step (3) is replaced by drop coating, and both sides of the polyester film are coated with a coating thickness of 10 μm.

[0063] Comparative Example 1

[0064] To verify that the layered flexible nanomaterials with ion-electron synergistic thermoelectric response of the present invention can be endowed with excellent flame retardant properties and fire warning functions through a simple coating method, an uncoated polyester (PET) film was used as a comparison, with no treatment performed on the PET. The fire warning and vertical burning test results are shown in Table 1.

[0065] Test method:

[0066] (1) Scanning electron microscopy (SEM): The morphology of the coating was observed using a scanning electron microscope (Verios G4UC, Thermo Fisher), with an electron beam acceleration voltage of 10kV. The sample was attached to the sample stage surface with conductive adhesive, and then sputtered with gold before testing.

[0067] (2) Vertical burning test: The test sample of 125mm×13mm×0.5mm was placed vertically on the Bunsen burner at a position of 10mm, and exposed to the flame height of the Bunsen burner of 20mm. After burning for 20s, its burning behavior and data were recorded.

[0068] (3) Fire warning test: Connect the 25mm×76mm×0.5mm test sample to the 1mV trigger voltage alarm through the wire. Expose one end of the sample to the Bunsen lamp at a position of 10mm. The flame height of the Bunsen lamp is 20mm. Record the alarm time of the sample.

[0069] (4) Temperature sensing test: Connect the 25mm×76mm×0.5mm test sample to the multimeter via wires, and place one end of the sample on the heating stage. Record the output voltage curve of the test sample and the set temperature of the heating stage by setting the temperature of the heating stage.

[0070]

[0071] As shown in Table 1, the coating of the present invention can impart excellent flame retardant properties and fire warning function to flammable substrates. Examples 1-9 all achieved UL-94 V0 level flame retardant performance in the vertical burning test. In Comparative Example 1, the uncoated sample burned completely in the vertical burning test. Figure 3 As shown, the nano-coating exhibits a layered nanosheet stacked structure, which has excellent thermal stability and layered barrier properties. When exposed to high temperatures, it undergoes a synergistic carbonization reaction with the conductive polymer, causing the nanosheets to bond tightly together and form a dense, porous barrier layer, enabling the coating to exert a good flame retardant effect.

[0072] In fire alarm testing, Example 1 was able to trigger a voltage alarm with a response voltage of 1mV in 1.81s, and the alarm function exhibited excellent repeatability. Comparative Example 1 failed to trigger the voltage alarm. This is because the ion-electron synergistic thermoelectric response layered flexible nano-flame-retardant coating prepared in this invention, when exposed to high temperatures, causes cations in the ion solution to migrate from high to low temperatures, forming an ionic potential and an ionic electric field. Simultaneously, internal electrons are driven by thermal and electric forces to migrate from high to low temperatures, thus forming an electronic potential. The ionic and electronic potentials form the thermal output voltage of the coating, which triggers the voltage alarm.

[0073] Application Example 1

[0074] To verify that the invented layered flexible nano-flame-retardant coating with ion-electron synergistic thermoelectric response possesses highly sensitive temperature sensing and repeatable early warning functions, the nano-coating prepared in Example 1 was subjected to temperature sensing tests. A multimeter and the nano-coating were connected using wires and copper foil. Figure 1 When one end of the nano-coating is placed on a 50°C heating stage, it rapidly outputs a voltage, which then stabilizes at 0.6mV. As the temperature increases, the rate of voltage increase accelerates, and the maximum output voltage gradually increases. Furthermore, the heat treatment temperature and the maximum output voltage exhibit a strong linear relationship, indicating that the coating possesses highly sensitive temperature sensing capabilities. Figure 2 When the heating stage was set to 200℃, the voltage rapidly increased and stabilized at 3.4mV within 30 seconds. After the coating was removed from the heating stage, its temperature and output voltage dropped rapidly, reaching 0.25mV after 20 seconds of cooling. After 100 cycles, the maximum output voltage of the coating remained at 3.4mV, indicating that the nano-coating possesses excellent repeatable early warning functionality.

[0075] Application Example 2

[0076] To verify the accurate detection capability of the invented coating for abnormal temperature rise in flexible electronic flammable substrates, this invention connected it to a wireless transmission device and conducted temperature sensing tests. Figure 2 As shown, the maximum output voltage of the nano-coating prepared in Example 1 exhibits a good linear relationship with the heat treatment temperature. The relationship U is obtained through linear fitting. max =0.0197T-0.5583. Based on this sensing characteristic, the coating was further connected to a wireless signal transmission device, enabling real-time transmission of temperature data to the mobile terminal. During the heating process, the mobile device can accurately monitor changes in ambient temperature with an accuracy of ±1℃. When the temperature reaches a preset warning threshold (200℃), the system can immediately issue an alarm. Figure 5 As shown, the coating can effectively issue an early warning during the abnormal temperature rise stage before the open flame appears, significantly advancing the fire warning time from "after the open flame appears" to the "latent period", thus winning valuable time for subsequent emergency response.

[0077] The technology provided by this invention overcomes the technical problems of existing thermoelectric materials being unable to achieve accurate, sensitive, and stable temperature sensing in fire early warning, and having poor flame retardant effect. It can be widely used in the field of electronic materials with high fire protection requirements.

Claims

1. A method for preparing a layered flexible nano-flame-retardant coating with ion-electron synergistic thermoelectric response, characterized in that: A conductive polymer solution and a layered material with thermoelectric function are ultrasonically dispersed and mixed with an ionic solution A at a mass ratio of 1:1:0.1 to 1:1:0.5 to obtain a coating with ion-electron synergistic thermoelectric response. The coating is applied to the surface of a flammable material in a flexible electronic device and dried to obtain a layered flexible nano flame-retardant coating with ion-electron synergistic thermoelectric response. The conductive polymer solution is prepared through the following steps. Step S1: Prepare a conductive polymer solution. Step S1.1: Add sodium polystyrene sulfonate solution, initiator A and catalyst A to solvent A with a pH of 4-7, and disperse them evenly in the solvent to obtain mixed solution A; Step S1.2: Adjust the reaction temperature to 0~50℃, add organic thermoelectric monomer A to mixed solution A, and carry out the mixed reaction for 8~24h to obtain reaction solution A; Step S1.3: After washing the reaction solution A by centrifugation 3-6 times with solvent B, dissolve it in deionized water and treat it in an ultrasonic homogenizer for 20-120 minutes to obtain a conductive polymer solution. The layered material with thermoelectric properties is prepared through the following steps. Step S2: Prepare a layered structure with thermoelectric function. Step S2.1: By ultrasonic treatment, the layered material is uniformly dispersed in solvent C with a pH of 4-7, morphology guiding agent A is added, and ultrasonic treatment is continued to make it uniformly loaded on the surface of the layered material to obtain reaction solution B. Step S2.2: Add initiator B and thermoelectric monomer B to reaction solution B, and react in a water bath at 30~80℃ for 3~12h to obtain reaction solution C; Step S2.3: After washing the reaction solution C by centrifugation 3-6 times with solvent D, dissolve it in deionized water to obtain a layered material with thermoelectric function.

2. The method for preparing a layered flexible nano-flame-retardant coating with ion-electron synergistic thermoelectric response according to claim 1, characterized in that: In step S1.1, the mass ratio of sodium polystyrene sulfonate to thermoelectric monomer A is 1:3 to 10:1, the mass ratio of initiator A to thermoelectric monomer A is 1:50 to 2:1, and the mass ratio of catalyst A to thermoelectric monomer A is 1:100 to 1:

10.

3. The method for preparing a layered flexible nano-flame-retardant coating with ion-electron synergistic thermoelectric response according to claim 1, characterized in that: In step S2.1, the mass ratio of morphology guiding agent A to layered material is 1:3 to 4:1; in step S2.2, the mass ratio of initiator B to layered material is 1:50 to 3:1; and the mass ratio of thermoelectric monomer B to layered material is 1:10 to 3:

1.

4. The method for preparing a layered flexible nano-flame-retardant coating with ion-electron synergistic thermoelectric response according to claim 1, characterized in that: The ionic solution A is at least one of 1-butyl-3-methylimidazolium octyl sulfate, 1-octyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium tetrafluoroborate, or trihexyltetradecylphosphonium.

5. The method for preparing a layered flexible nano-flame-retardant coating with ion-electron synergistic thermoelectric response according to claim 1, characterized in that: Solvent A is at least one of deionized water, ethanol, methanol, isopropanol, n-butanol, and acetone; Solvent B is at least one of deionized water, ethanol, methanol, isopropanol, n-butanol, and acetone; The initiator A is at least one of potassium persulfate, ammonium persulfate, azobisisobutyronitrile, benzoyl peroxide, azobisisobutyramidine hydrochloride, and tert-butanol peroxide; The catalyst A is at least one of ferric chloride, potassium persulfate, ammonium persulfate, aluminum trichloride, and tin tetrachloride; The thermoelectric monomer A is at least one of 3,4-ethylenedioxythiophene, aniline, pyrrole, and carbazole.

6. The method for preparing a layered flexible nano-flame-retardant coating with ion-electron synergistic thermoelectric response according to claim 1, characterized in that: The layered material is graphene, , and At least one of them; The morphology guiding agent A is at least one of polyvinylpyrrolidone, polyethylene glycol, polyethyleneimine, hexadecyltrimethylammonium bromide, and sodium dodecyl sulfate; The initiator B is one or more of potassium persulfate, ammonium persulfate, azobisisobutyronitrile, benzoyl peroxide, and tert-butanol peroxide; the thermoelectric monomer B is at least one of thiophene, 3-hexylthiophene, 3,4-ethylenedioxythiophene, aniline, pyrrole, and carbazole. The solvent C is at least one selected from deionized water, ethanol, methanol, isopropanol, n-butanol, and acetone. The solvent D is at least one of deionized water, ethanol, methanol, isopropanol, n-butanol, and acetone.

7. A layered flexible nano-flame-retardant coating with ion-electron synergistic thermoelectric response, characterized in that... It is prepared by the method for preparing a layered flexible nano flame-retardant coating with ion-electron synergistic thermoelectric response as described in any one of claims 1 to 6.

8. An application of a layered flexible nano-flame-retardant coating with ion-electron synergistic thermoelectric response, characterized in that... A layered flexible nano flame-retardant coating with ion-electron synergistic thermoelectric response, as described in any one of claims 1 to 6, is applied to the surface of a flammable material in a flexible electronic device. The coating method is one of spraying, dripping, or dipping. The flammable material in the flexible electronic device is a polyester film or polyurethane foam.

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