Method for measuring thermal conductivity of material by using photothermal conversion effect and thermoelectric sheet

Abstract

The invention relates to a method for measuring the thermal conductivity of a material by using a photothermal conversion effect and a thermoelectric sheet, which comprises the following steps: S1, placing a sample to be measured and the thermoelectric sheet on the upper surface of a constant-temperature substrate, and tightly attaching a photothermal / thermal conductive composite material layer with the photothermal conversion effect to the upper surfaces of the sample to be measured and the thermoelectric sheet to form a test system; and S2, performing light source radiation treatment on the heat conduction material layer of the test system obtained in S1, recording the voltage value of the thermoelectric sheet, and obtaining the heat conductivity of the to-be-tested sample based on the voltage value. Compared with the prior art, the method has the advantages that the application of measuring the thermal conductivity of the material by utilizing photothermal conversion is realized for the first time, the change of the thermal conductivity can be obtained by observing a thermoelectric voltage value, the method is simple in preparation, a photothermal and thermal conduction material system can be repeatedly utilized, and the method has a wide application range and the like.

Description

Technical Field

[0001] This invention belongs to the field of material thermal conductivity testing technology, and relates to a method for measuring the thermal conductivity of materials using photothermal conversion effect and thermoelectric elements. Background Technology

[0002] The measurement of material thermal conductivity has wide applications in fields such as new material research and development, material performance evaluation, and geological environment monitoring. Currently, the measurement of material thermal conductivity mainly relies on large laboratory equipment or small portable devices powered by electricity. This results in drawbacks such as high cost, long processing time, complex sampling procedures, and the need for additional energy input. For example, the high-precision in-plane thermal conductivity measurement device and method provided in Chinese patent application CN120446200A combines a contact heat flow meter with a vacuum insulation module. It uses a servo linear motor to drive a displacement transmission system to construct a stable axial heat flow field and combines a dual-length difference method to eliminate contact thermal resistance interference, adapting to different sample sizes and temperature ranges to achieve high-precision in-plane thermal conductivity measurement. However, its measurement process is complex and highly dependent on equipment and location.

[0003] On the other hand, since sunlight is a renewable and clean energy source and is readily available in nature, it has been widely used in fields such as seawater desalination, oil filtration, solar cells, and chemical catalysis. Therefore, it is particularly important to be able to use sunlight in nature to test the thermal conductivity of materials in situ. Summary of the Invention

[0004] The purpose of this invention is to provide a method for measuring the thermal conductivity of materials using the photothermal conversion effect and thermoelectric elements. It fully utilizes the principle that light radiation can be converted into heat under the action of a photothermal absorption film. Based on the fact that the generated heat propagates between the thermoelectric element and the test sample with different thermal conductivity, resulting in different surface temperatures of the thermoelectric element, the thermal conductivity of the test material can be determined by measuring the voltage of the thermoelectric element. Compared with other laboratory measuring equipment, this method has significant advantages in real-time measurement.

[0005] The objective of this invention can be achieved through the following technical solutions: A method for measuring the thermal conductivity of a material using the photothermal conversion effect and a thermoelectric element includes the following steps: S1. The sample to be tested and the thermoelectric element are placed on the upper surface of the constant temperature substrate, and then the photothermal / thermal conductive composite material layer with photothermal conversion effect is tightly attached to the upper surface of the sample to be tested and the thermoelectric element to form a test system. S2. The thermally conductive material layer of the test system obtained in S1 is subjected to light source radiation treatment, the voltage value of the thermoelectric element is recorded, and the thermal conductivity of the sample to be tested is obtained based on the established standard curve of voltage value and thermal conductivity.

[0006] Furthermore, during the test, the sample under test and the thermoelectric element are identical in shape and size (i.e., dimensional parameters such as thickness, length, and width are identical), and they are kept in close contact.

[0007] Furthermore, in S1, the photothermal / thermal conductive composite material layer is prepared through the following steps: (1) First, a portion of the flexible polymer is coated into a film to obtain a polymer substrate; (2) Then coat a layer of high thermal conductivity material onto the polymer substrate; (3) Finally, the photothermal conversion material is mixed with another part of the flexible polymer, and then coated onto the high thermal conductivity material layer and cured to form a photothermal conversion film, thus obtaining the photothermal / thermal conductive composite material layer.

[0008] Furthermore, in steps (1) and (3), the flexible polymer is one or more of silicone rubber, block copolymers or thermoplastic biodegradable plastics; The silicone rubber is selected from at least one of methyl silicone rubber, methyl vinyl silicone rubber, methyl phenyl vinyl silicone rubber, fluorosilicone rubber, nitrile silicone rubber, phenylene silicone rubber, ethyl silicone rubber, and silicone nitrogen rubber; The block copolymer is at least one of hydrogenated styrene / butadiene block copolymer, styrene / isoprene / styrene block copolymer, styrene / hexene-butene / styrene block copolymer, and styrene / ethylene-propylene / styrene block copolymer; The thermoplastic biodegradable plastic is selected from at least one of polylactic acid plastics, polybutylene succinate plastics, or polyhydroxyalkanoate plastics.

[0009] Furthermore, in step (2), the high thermal conductivity material layer is composed of a mixture of low-melting-point liquid metal and high thermal conductivity filler. The low-melting-point liquid metal is at least one of gallium, gallium-indium alloy, gallium-indium-tin alloy, tin-bismuth alloy, mercury, or rubidium. The high thermal conductivity filler is at least one of boron nitride, graphite, graphene, carbon nanotubes, diamond, alumina, magnesium oxide, zinc oxide, copper powder, nickel powder, and silver nanowires.

[0010] Furthermore, in step (3), the photothermal conversion material is at least one of graphene, carbon nanotubes, metal nanoparticles or conductive polymer nanoparticles.

[0011] Furthermore, the thickness of the polymer substrate can be 50~800μm; The thickness of the high thermal conductivity material layer can be 100~1000μm; The thickness of the photothermal conversion material layer can be 50~1000μm.

[0012] Furthermore, the thermoelectric element is a semiconductor thermoelectric cooler, model TEC1-12702, with dimensions of 30mm in length, 30mm in width, and 4mm in thickness, purchased from Guangzhou Herui Electronics Co., Ltd.

[0013] Furthermore, the temperature range of the constant temperature substrate is between 5-35°C.

[0014] Furthermore, the time for light source radiation treatment shall not be less than 6 minutes; The recorded voltage values ​​of the thermoelectric element are the values ​​after the output voltage has stabilized, and the recording time is no less than 1 minute.

[0015] Furthermore, in S2, the process of establishing the standard curve is as follows: A series of test samples with known thermal conductivity were used to construct a test system according to the method in S1. Then, the voltage values ​​of the corresponding thermoelectric elements were tested under the same conditions in S2. Based on this, a standard curve of the voltage value of the thermoelectric element and the thermal conductivity of the test sample was plotted.

[0016] In principle, the heat transfer of the entire system established by this invention can be analyzed by the following longitudinal heat transfer equation (1).

[0017] (1) in It is the total heat flux generated by the absorption and conversion of sunlight by the system (which depends on the energy density of the sun and the properties of the materials, namely light absorption and heat conversion coefficient). It is through the heat flux of the thermoelectric element. It is measured by the heat flux of the sample to be tested. This indicates thermal convection. and These are the thermal conductivity of the thermoelectric element and the sample under test, respectively. and These are the temperatures of the thermoelectric element and the upper surface of the sample under test, respectively. It is the temperature of the temperature control station (i.e., the constant temperature base) (which can be set to 15 ℃). and These are the cross-sectional area and length through which heat flows, respectively. The sample to be tested in this study has the same geometric parameters as the thermoelectric element. In addition, horizontal heat transfer in the heat-conducting layer ( ) can be written as formula (2).

[0018] (2) in, The thermal conductivity of the heat-conducting layer is... and Let be the cross-sectional area and length through which the heat flows, respectively. Combining formulas (1) and (2), we can derive: (3) in, This represents the temperature difference between the upper and lower surfaces of the thermoelectric element. According to formula (4), when other parameters remain constant, Only with Related. According to the Seebeck effect (4) in and These are the thermoelectric voltage and the Seebeck coefficient, respectively. Therefore, the thermal conductivity of a sample can be determined by monitoring the thermoelectric voltage, which theoretically demonstrates the feasibility of the testing method provided by this invention.

[0019] The working principle of this invention is as follows: The energy radiated by the light source can be absorbed by the photothermal conversion material and converted into heat. This heat can then propagate between the thermoelectric element and the material under test. Due to the difference in thermal conductivity between the thermoelectric element and the material under test, the heat flow through them differs, resulting in different surface temperatures. High thermal conductivity materials can facilitate the lateral propagation of heat, widening the temperature difference. Therefore, the thermal conductivity of the material under test can be determined by detecting the output voltage of the thermoelectric element.

[0020] Compared with the prior art, the present invention has the following advantages: (1) This invention innovatively uses a combination of photothermal and thermally conductive material system and thermoelectric sheet to realize the measurement of thermal conductivity under light source radiation, which can then be applied in the fields of environmental and geological testing.

[0021] (2) The present invention realizes the encapsulated photothermal and thermal conductive material system through the coating film-making technology with adjustable thickness, and has a wide range of applications.

[0022] (3) This invention generates and transfers heat in the photothermal and thermally conductive material system through photothermal conversion effect, thereby realizing the measurement of the thermal conductivity of the material. It replaces the instruments and equipment of the original method, reduces the testing cost, and is conducive to real-time monitoring.

[0023] (4) The present invention can achieve measurement under different weather conditions by using photothermal materials with different light absorption rates or correcting the light power density of the light source radiation.

[0024] (5) The present invention can make a thermally conductive material by mixing fillers with low melting point liquid metals with fillers of different thermal conductivity. The thermally conductive material with enhanced thermal conductivity will help improve the sensitivity of thermal conductivity measurement and is easy to adapt to various application occasions.

[0025] (6) The present invention can be further extended to measure the thermal resistance and thickness of the sample. That is, when the thermal conductivity of the sample is consistent, the thickness of the sample will affect its overall thermal resistance, which will then be reflected in the thermoelectric voltage. Attached Figure Description

[0026] Figure 1 Scanning electron microscope images of the gallium-indium eutectic alloy and reduced graphene oxide core-shell structured nanoparticles prepared in Example 1; Figure 2 Transmission electron microscope images of the gallium-indium eutectic alloy and reduced graphene oxide core-shell structured nanoparticles prepared in Example 1. Figure 3 The image shows a scanning electron microscope image of the gallium-indium eutectic alloy and graphene mixture prepared in Example 1. Figure 4 An optical photograph of the gallium-indium eutectic alloy and graphene mixture prepared in Example 1 coated on a pre-cured polymer substrate; Figure 5 An optical photograph of the front view of the photothermal and thermally conductive material system prepared in Example 1; Figure 6 An optical photograph of the bottom surface of the photothermal and thermally conductive material system prepared in Example 1; Figure 7 The image shows a scanning electron microscope (SEM) image of the cross-section of the photothermal and thermally conductive material system prepared in Example 1. Figure 8 This is a schematic diagram illustrating the measurement of material thermal conductivity using a system combining photothermal conversion effect and thermoelectric elements with photothermal and thermally conductive materials in Example 1. Figure 9 The results are the experimental results of the thermal conductivity of the test material and the average output voltage of the thermoelectric element obtained by using this method in Example 1. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0029] As used herein, the terms "and / or," "or / and," and "and / or" encompass any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that, in this application, the technical solution undoubtedly includes solutions connected by "logical AND," and also undoubtedly includes solutions connected by "logical OR."

[0030] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0031] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0032] This document only specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0033] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows temperature fluctuations within the precision range controlled by the instrument, such as ±5°C, ±4°C, ±3°C, ±2°C, or ±1°C.

[0034] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0035] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0036] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0037] In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0038] Unless otherwise specified, all preparations and tests described herein took place at 25°C.

[0039] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means that other steps and ingredients may be added without affecting the final result. The compositions and methods / processes of the present invention comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. No distinction is made between the terms “efficacy,” “performance,” “effect,” and “potency” herein.

[0040] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0041] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, but sequentially is preferred.

[0042] In the following embodiments, the aliphatic aromatic random copolyester (Ecoflex) is sourced from Smooth-On Corporation, USA, model number 0030. The liquid metal gallium-indium eutectic alloy is sourced from Shenyang Jiabei Commercial Trading Co., Ltd.

[0043] Unless otherwise specified, all other raw materials or processing techniques are commercially available materials or conventional processing techniques in the field.

[0044] Example 1 The A and B components of the aliphatic aromatic random copolyester (Ecoflex) were manually mixed at a volume ratio of 1:1 at room temperature, and a 200 μm thick film was coated onto a flat polyethylene plate using a coater. The coated polymer substrate film was then cured in a 60°C oven for 20 min to obtain the polymer substrate of the composite material.

[0045] 10 g of gallium-indium eutectic alloy and 0.2 g of graphene were placed in a polytetrafluoroethylene (PTFE) beaker and stirred evenly using a mixer at a speed of 700 rad / min for 30 min. After stirring, the mixture was observed to be fully mixed and exhibiting a silvery, viscous paste-like morphology. It is important to note that this process must be performed at a temperature above the melting point of the gallium-indium eutectic alloy (16°C).

[0046] The above-mentioned gallium-indium eutectic alloy and graphene mixture was coated onto a pre-cured polymer substrate using a coater to form a 1000 μm thick mixture paste. Then, a mixture of Ecoflex components A and B was prepared using the same method, and a 300 μm thick polymer layer was coated onto the mixture paste.

[0047] 1 g of Ecoflex component A and 2 ml of a hexane dispersion of gallium indium eutectic alloy and reduced graphene oxide core-shell nanoparticles were placed in a plastic bottle and placed on a 60°C hot plate for 6 h to allow the hexane solvent to evaporate completely. The mixture was then manually stirred until homogeneous. The gallium indium eutectic alloy and reduced graphene oxide core-shell nanoparticles were observed to be fully mixed with component A, exhibiting a gray, viscous, and sticky morphology.

[0048] The above-mentioned gallium indium eutectic alloy and reduced graphene oxide core-shell structured nanoparticles and component A were mixed together with component B of 1 g Ecoflex by manual stirring. The mixture was then coated with a 50 μm thick layer on the pre-coated polymer layer using a coater. The coated material was cured in an oven at 60 °C for 20 min to obtain a photothermal and thermally conductive material system (i.e., a photothermal / thermally conductive composite material layer).

[0049] Figure 1 Scanning electron microscope images of gallium indium eutectic alloy and reduced graphene oxide core-shell nanoparticles are shown. It can be seen that the gallium indium eutectic alloy and reduced graphene oxide core-shell nanoparticles are spherical, which causes the material to scatter visible light multiple times, resulting in the material's gray appearance. In addition, visible light is converted into heat through multiple scattering.

[0050] Figure 2 Transmission electron microscopy images of gallium indium eutectic alloy and reduced graphene oxide core-shell structured nanoparticles are shown. It can be seen that the surface of the gallium indium eutectic alloy nanoparticles is coated with reduced graphene oxide.

[0051] Figure 3 Scanning electron microscope images of a mixture of gallium indium eutectic alloy and graphene are shown, demonstrating that graphene can be uniformly mixed into the gallium indium eutectic alloy through the above process.

[0052] Figure 4 An optical photograph shows a mixture of gallium indium eutectic alloy and graphene coated on a pre-cured polymer substrate, demonstrating that the mixture of gallium indium eutectic alloy and graphene is uniformly coated using the above coating process.

[0053] Figure 5 An optical photograph of the front of the photothermal and thermally conductive material system prepared by the above method is shown. It can be seen that the upper layer is a photothermal layer made of gallium indium eutectic alloy and reduced graphene oxide core-shell structured nanoparticles.

[0054] Figure 6 An optical photograph of the bottom surface of the photothermal and thermally conductive material system prepared by the above method is shown. It can be seen that the photothermal and thermally conductive material system is filled with a uniform and continuous mixture of gallium indium eutectic alloy and graphene as a thermally conductive material through a transparent polymer substrate.

[0055] Figure 7 Scanning electron microscope images of the cross-section of the photothermal and thermally conductive material system prepared by the above method are shown. It can be seen that the photothermal and thermally conductive material system has a three-layer structure, with a thermally conductive material of about 1000 μm thickness filling the space between the upper photothermal material and the lower polymer substrate.

[0056] Figure 8 This diagram illustrates the measurement of thermal conductivity of a test system consisting of a thermoelectric element and a photothermal / thermal conductive composite material layer prepared by the aforementioned method. As can be seen, the photothermal / thermal conductive composite material layer prepared by the above method is placed on top of the thermoelectric element and the sample under test. Simultaneously, the thermoelectric element and the bottom of the sample under test are tightly integrated with a temperature control system (serving as a constant-temperature substrate). Optical radiation, through the photothermal conversion material, serves as the input heat source for the system, and the thermal conductivity of the material under test is obtained by measuring the output voltage of the thermoelectric element.

[0057] Figure 9The experimental results of the thermal conductivity of the test material and the average output voltage of the thermoelectric element, measured by the above method, are shown. The thermoelectric element (TEC1-12702) with dimensions (30mm long, 30mm wide, 4mm thick) was purchased from Guangzhou Herui Electronics Co., Ltd. The dimensions of the test sample are the same as those of the thermoelectric element. The temperature control system (i.e., the constant-temperature substrate) was set at 15℃. The thickness of the photothermal layer was 50μm, the thickness of the polymer layer below the photothermal layer was 300μm, the thickness of the thermally conductive material layer was 1.14mm, and the thickness of the bottom polymer substrate was 200μm. The dimensions of the prepared photothermal / thermally conductive composite material layer were 60mm long and 30mm wide. A xenon lamp with a power density of 1000 W / m² was used. 2 The processing time for light radiation is 6 minutes.

[0058] As shown in the figure, the output voltage of the thermoelectric element decreases as the thermal conductivity of the sample increases. Based on this measurement result, a curve relating the output voltage of the thermoelectric element to the thermal conductivity of the sample can be fitted, and then the thermal conductivity of the unknown material can be measured using this method.

[0059] A kaolin sample was prepared as the test sample. After measurement with a thermal conductivity meter, the thermal conductivity of the sample was 0.56 ± 0.031 W / mK. Following the above testing procedure, the measured thermal conductivity of the kaolin sample was 0.57 W / mK, which is very close to the value measured by the thermal conductivity meter. This indicates that the determination method of the present invention has good feasibility.

[0060] Examples 2-5: Compared to Example 1, most of the contents are the same, except that the low-melting-point liquid metal and reduced graphene oxide core-shell structured nanoparticles are replaced with equal amounts of graphene, carbon nanotubes, other metal nanoparticles (gold nanoparticles), or polymer nanoparticles (polydopamine nanoparticles).

[0061] Examples 6-9: Compared to Example 1, most of the contents are the same, except that the mixture of low-melting-point liquid metal and high thermal conductivity filler is replaced with metal film (copper foil), conductive polymer film (polythiophene film), boron nitride film, or graphite film.

[0062] Examples 10-14: The majority of the components are the same as in Example 1, except that the gallium-indium alloy is replaced with an equal amount of metallic gallium, gallium-indium-tin alloy, tin-bismuth alloy, metallic mercury, or metallic rubidium.

[0063] Examples 15-26: Compared to Example 1, most of the components are the same, except that the flexible polymer, aliphatic aromatic random copolyester (Ecoflex), is replaced by equal masses of dimethyl silicone rubber, methyl vinyl silicone rubber, methyl phenyl vinyl silicone rubber, fluorosilicone rubber, nitrile silicone rubber, phenylene silicone rubber, ethyl silicone rubber, silicone nitrile rubber, hydrogenated styrene / butadiene block copolymer, styrene / isoprene / styrene block copolymer, styrene / hexene-butene / styrene block copolymer, and styrene / ethylene-propylene / styrene block copolymer.

[0064] Example 27: Compared with Example 1, most of the contents are the same, except that the photothermal conversion material and the flexible polymer particles are directly mixed in a mixer when preparing the photothermal material.

[0065] Example 28: The process is largely the same as in Example 1, except that the low-melting-point liquid metal and other high thermal conductivity fillers are mixed in a vacuum using a planetary mixer during the preparation of the thermally conductive material.

[0066] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for measuring the thermal conductivity of materials using the photothermal conversion effect and thermoelectric elements, characterized in that, Includes the following steps: S1. The sample to be tested and the thermoelectric element are placed on the upper surface of the constant temperature substrate, and then the photothermal / thermal conductive composite material layer with photothermal conversion effect is tightly attached to the upper surface of the sample to be tested and the thermoelectric element to form a test system. S2. The thermally conductive material layer of the test system obtained in S1 is subjected to light source radiation treatment, the voltage value of the thermoelectric element is recorded, and the thermal conductivity of the sample to be tested is obtained based on the established standard curve of voltage value and thermal conductivity.

2. The method for measuring the thermal conductivity of a material using the photothermal conversion effect and a thermoelectric element according to claim 1, characterized in that, During the test, the sample under test and the thermoelectric element are identical in shape and size, and the two are kept in close contact.

3. The method for measuring the thermal conductivity of a material using the photothermal conversion effect and a thermoelectric element according to claim 1, characterized in that, In S1, the photothermal / thermal conductive composite material layer is prepared through the following steps: (1) First, a portion of the flexible polymer is coated into a film to obtain a polymer substrate; (2) Then coat a layer of high thermal conductivity material onto the polymer substrate; (3) Finally, the photothermal conversion material is mixed with another part of the flexible polymer, then coated onto the high thermal conductivity material layer and cured to obtain the photothermal / thermal conductivity composite material layer.

4. The method for measuring the thermal conductivity of a material using the photothermal conversion effect and a thermoelectric element according to claim 3, characterized in that, In steps (1) and (3), the flexible polymer is one or more of silicone rubber, block copolymers or thermoplastic biodegradable plastics; The silicone rubber is selected from at least one of methyl silicone rubber, methyl vinyl silicone rubber, methyl phenyl vinyl silicone rubber, fluorosilicone rubber, nitrile silicone rubber, phenylene silicone rubber, ethyl silicone rubber, and silicone nitrogen rubber; The block copolymer is at least one of hydrogenated styrene / butadiene block copolymer, styrene / isoprene / styrene block copolymer, styrene / hexene-butene / styrene block copolymer, and styrene / ethylene-propylene / styrene block copolymer; The thermoplastic biodegradable plastic is selected from at least one of polylactic acid plastics, polybutylene succinate plastics, or polyhydroxyalkanoate plastics.

5. The method for measuring the thermal conductivity of a material using the photothermal conversion effect and a thermoelectric element according to claim 3, characterized in that, In step (2), the high thermal conductivity material layer is composed of a mixture of low-melting-point liquid metal and high thermal conductivity filler. The low-melting-point liquid metal is at least one of gallium, gallium-indium alloy, gallium-indium-tin alloy, tin-bismuth alloy, mercury, or rubidium. The high thermal conductivity filler is at least one of boron nitride, graphite, graphene, carbon nanotubes, diamond, alumina, magnesium oxide, zinc oxide, copper powder, nickel powder, and silver nanowires.

6. The method for measuring the thermal conductivity of a material using the photothermal conversion effect and a thermoelectric element according to claim 3, characterized in that, In step (3), the photothermal conversion material is at least one of graphene, carbon nanotubes, metal nanoparticles or conductive polymer nanoparticles.

7. The method for measuring the thermal conductivity of a material using the photothermal conversion effect and a thermoelectric element according to claim 1, characterized in that, The thermoelectric element is a semiconductor thermoelectric cooler.

8. The method for measuring the thermal conductivity of a material using the photothermal conversion effect and a thermoelectric element according to claim 1, characterized in that, The temperature of the constant temperature substrate is 5-35℃.

9. The method for measuring the thermal conductivity of a material using the photothermal conversion effect and a thermoelectric element according to claim 1, characterized in that, The time for light source radiation treatment shall not be less than 6 minutes; The recorded voltage values ​​of the thermoelectric element are the values ​​after the output voltage has stabilized, and the recording time is no less than 1 minute.

10. The method for measuring the thermal conductivity of a material using the photothermal conversion effect and a thermoelectric element according to claim 1, characterized in that, In S2, the process of establishing the standard curve is as follows: A series of test samples with known thermal conductivity were used to construct a test system according to the method in S1. Then, the voltage values ​​of the corresponding thermoelectric elements were tested under the same conditions in S2. Based on this, a standard curve of the voltage value of the thermoelectric element and the thermal conductivity of the test sample was plotted.

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