Porous material sensitive to carbon dioxide, preparation method of porous material and carbon dioxide detection membrane

Abstract

The invention relates to the technical field of carbon dioxide detection, and discloses a porous material sensitive to carbon dioxide, a preparation method of the porous material and a carbon dioxide detection film. The porous material comprises a porous elastomer matrix and a modified carbon nanomaterial embedded in the pore wall of the porous elastomer matrix; wherein the porous elastomer matrix has a through hole structure; the modified carbon nanomaterial is a polydopamine and alkyl chain dual modified carbon nanomaterial. And mixing the modified carbon nanomaterial, an elastomer solution or an elastomer reaction stock solution and a high-surface tension liquid, emulsifying and curing to obtain the porous material. The invention also comprises a carbon dioxide detection membrane prepared from the porous material. The porous material sensitive to carbon dioxide provided by the invention has enhanced structural reliability and wider carbon dioxide detection range, and is high in sensitivity and short in response time; the flexible electronic wearable device has the advantages of flexibility, bending resistance and good structural stability, and can be reliably applied to the fields of flexible electronic wearable devices and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon dioxide detection, and particularly relates to a porous material sensitive to carbon dioxide, a preparation method of the porous material and a carbon dioxide detection film. BACKGROUND

[0002] Carbon dioxide is a common compound in the atmosphere and is part of the atmospheric composition, and is closely related to people's daily life. In the field of life science, carbon dioxide shoulders the heavy responsibility of maintaining and regulating the pH balance and ion balance of the body fluid of an organism; and as a small molecule gas, it has certain water solubility, good biological membrane permeability and biocompatibility. In addition, the metabolic process of carbon dioxide molecules is closely related to many life activities of an organism, and plays an extremely important role in the growth process of plants and animals. With the increasing improvement of people's living standards, people pay more and more attention to environmental protection, and real-time monitoring and control of the carbon dioxide concentration are extremely important in the fields of medical treatment, agriculture, industry and environmental protection. Therefore, it is of great significance to develop a carbon dioxide sensor with high sensitivity, long service life, fast response time and low cost, and the sensitive element as the core part of the sensor is extremely important for the performance of the sensor.

[0003] The commonly used carbon dioxide detection principles at the present stage include an electrochemical principle and an optical sensing principle. The electrochemical principle is mainly based on the change in the electrical performance caused by the chemical action of the sensitive element and carbon dioxide. The most commonly used are resistance type and capacitance type, and the sensing technology is simple and low in cost, and has been widely developed. Inorganic metal oxides such as ZnO, CuO and CdO are mainly used, and when in contact with carbon dioxide, the inorganic metal oxides can change the surface charge through oxidation / reduction, electron charge transfer, adsorption or chemical reaction, so as to change the electrical performance of the sensitive element, thereby reflecting the carbon dioxide concentration. However, this method has the problem of adsorption saturation concentration, which adversely affects the sensitivity and response time.

[0004] The main detection method in optical sensing is non-dispersive infrared optical detection, which uses an infrared light source to irradiate a sample in a chamber with a filter and an infrared detector, and the gas content can be obtained according to the absorbance of the sample at a wavelength of 4.24 μm through the Beer-Lambert law. Although this sensor has high precision, fast measurement and good long-term stability, the problems of complex device, high power consumption and high cost have not been well solved.

[0005] CN116773514A discloses a carbon dioxide detection device and a protective mask, which uses an optical detection method to detect carbon dioxide concentration based on the principle of color change when a pH indicator binds to carbon dioxide. However, the hydrophobic porous membrane and the sensitive material are bound together through non-covalent weak interactions, and the reliability of the sensitive element needs further improvement. Furthermore, the limited number and uncontrollable active binding sites prevent the detection of carbon dioxide gas over a wide range of concentrations.

[0006] CN112903755A describes a carbon dioxide sensor and its preparation method, which uses a mixture of polyethyleneimine and starch as the sensitive substance. However, the membrane structure is uncontrollable and it is easily saturated with adsorption under high concentrations of carbon dioxide gas, making it undetectable.

[0007] Therefore, there is an urgent need to develop a carbon dioxide detection membrane with high structural reliability and a wide detection range for use in electrochemical sensing. Summary of the Invention

[0008] The purpose of this invention is to overcome the problems existing in the prior art and provide a porous material sensitive to carbon dioxide, its preparation method, and a carbon dioxide detection membrane.

[0009] To achieve the above objectives, the first aspect of the present invention provides a porous material sensitive to carbon dioxide, wherein the porous material comprises a porous elastomer matrix and modified carbon nanomaterials embedded in the pore walls of the porous elastomer matrix;

[0010] The porous elastomer matrix has a through-hole structure;

[0011] The modified carbon nanomaterial is a carbon nanomaterial that has been modified with both polydopamine and alkyl chains.

[0012] A second aspect of the present invention provides a method for preparing a porous material according to the first aspect, wherein the method comprises: mixing, emulsifying and solidifying a modified carbon nanomaterial, an elastomer solution or an elastomer reaction stock solution and a high surface tension liquid to obtain the porous material.

[0013] A third aspect of the present invention provides a carbon dioxide detection membrane made of a porous material obtained by the porous material described in the first aspect and the method described in the second aspect.

[0014] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0015] (1) The porous material sensitive to carbon dioxide provided by the present invention has enhanced structural reliability and a wider carbon dioxide detection range, high sensitivity and short response time.

[0016] (2) The porous material in this invention is flexible and can withstand bending, with good structural stability, and can be reliably applied in fields such as flexible electronic wearables. Attached Figure Description

[0017] Figure 1 This is a wall structure diagram of the porous material prepared in Example 1 of the present invention at a magnification of 500.

[0018] Figure 2 This is a wall structure diagram of the porous material prepared in Example 1 of the present invention at a magnification of 100,000 times;

[0019] Figure 3 This is a wall structure diagram of the porous material prepared by Comparative Example 5 of the present invention at a magnification of 100,000 times. Detailed Implementation

[0020] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] The first aspect of the present invention provides a porous material sensitive to carbon dioxide, wherein the porous material comprises a porous elastomer matrix and modified carbon nanomaterials embedded in the pore walls of the porous elastomer matrix;

[0022] The porous elastomer matrix has a through-hole structure;

[0023] The modified carbon nanomaterial is a carbon nanomaterial that has been modified with both polydopamine and alkyl chains.

[0024] In this invention, "embedding" refers to a portion of the modified carbon nanomaterial being inside the matrix and another portion being outside the matrix.

[0025] During the research and development process, the inventors of this invention discovered that the existing technology has two main problems: first, the active material is not sufficiently bonded to the matrix, which may lead to the risk of the active material falling off during use; second, the sensitive material is mostly planar in both macroscopic and microscopic terms, with a small effective adsorption area and a narrow carbon dioxide detection range.

[0026] The carbon dioxide-sensitive porous material provided by this invention uses carbon nanomaterials modified with both polydopamine and alkyl chains as active materials, and has dual functions: the surface polydopamine can react with carbon dioxide to form aminocarbonate, and this reaction is reversible, which can respond to the concentration of carbon dioxide in the gas, and the concentration of carbon dioxide can be reflected by the resistance value of the porous material; the surface alkyl chains can provide the nanoparticles with lipophilicity, so that the nanoparticles can act as stabilizers to stabilize water-in-oil emulsions with high internal phase. By adjusting the size, concentration and amphiphilicity of the nanoparticles, the pore size and pore wall structure of the material can be controlled, which affects the carbon dioxide detection sensitivity and carbon dioxide detection range.

[0027] The porous material provided by this invention has a through-pore structure, which can effectively increase the effective adsorption area and enable carbon dioxide adsorption detection over a wide concentration range (wide detection range); in addition, the functional nanomaterials are embedded in the pore walls, which are firmly bonded and not easily detached, greatly enhancing the structural reliability of the entire material.

[0028] In addition, the porous matrix structure used in this invention is an elastomer material, which is flexible, resistant to bending, and has good structural stability, and can be reliably applied in fields such as flexible electronic wearables.

[0029] In some embodiments of the present invention, the porous elastomer matrix is ​​selected from at least one of polyurethane porous matrix, styrene-butadiene-styrene block copolymer porous matrix, polyolefin porous matrix, silicone rubber porous matrix, and polyacrylate porous matrix. The porous elastomer matrix in the present invention may be selected from porous thermoplastic elastomers and thermosetting elastomers.

[0030] In some embodiments of the present invention, the carbon nanomaterial is selected from at least one of carbon nanotubes, graphene, and conductive carbon black.

[0031] In some embodiments of the present invention, the specific surface area of ​​the modified carbon nanomaterial is greater than 100 g / m². 2 Preferably greater than 200g / m 2 .

[0032] In some embodiments of the present invention, the mass of the polydopamine is 3-10% of the modified carbon nanomaterial, preferably 4.3-8.9%.

[0033] In some embodiments of the present invention, the mass of the alkyl chain is 3.5-16% of the modified carbon nanomaterial, preferably 4.8%.

[0034] In some embodiments of the present invention, the alkyl chain comprises 2-3 short-chain alkyl chains and 1-2 long-chain alkyl chains.

[0035] In some embodiments of the present invention, the short-chain alkyl chain has 1-2 carbon atoms.

[0036] In some embodiments of the present invention, the long-chain alkyl chain has 8-18 carbon atoms, preferably 10-16.

[0037] In some embodiments of the invention, the alkyl chain is derived from at least one of hexadecyltrimethylammonium bromide, bis(tetradecyl)dimethylammonium chloride, dodecyltriethylammonium chloride, and bis(decyl)dimethylammonium chloride.

[0038] In some embodiments of the present invention, the mass ratio of the modified carbon nanomaterial to the porous elastomer matrix is ​​4-16:100, preferably 8-12:100, and more preferably 10:100. In the present invention, if the mass ratio is too small, a stable emulsion cannot be formed, making it difficult to form a porous material; if the mass ratio is too large, the liquid viscosity is too high, making it difficult to emulsify and form an emulsion.

[0039] In some embodiments of the present invention, the pore size of the porous material is 5-400 μm, preferably 20-200 μm.

[0040] In this invention, the pore size of the porous material can be adjusted by factors such as the amphiphilicity of the modified carbon nanomaterial (i.e., the type and amount of polydopamine and alkyl chains), the ratio of the modified carbon nanomaterial to the matrix, and the ratio of the continuous phase to the dispersed phase in the emulsion.

[0041] A second aspect of the present invention provides a method for preparing the porous material described in the first aspect, wherein the method comprises: mixing, emulsifying and solidifying a modified carbon nanomaterial, an elastomer solution or an elastomer reaction stock solution and a high surface tension liquid to obtain the porous material.

[0042] Existing porous materials with similar structures are basically obtained by first obtaining a porous material and then immersing the porous material in a carbon nanomaterial dispersion. The resulting porous material has some carbon nanomaterials attached to its inner wall, but the bonding force is poor, and the amount of carbon nanomaterials attached to the surface is difficult to control.

[0043] Existing technologies often employ a method of immersing porous materials in an active material solution to deposit active materials on the porous surface. However, due to poor compatibility between the active material and the porous material, the deposition effect is unsatisfactory, and there is a high risk of detachment over long-term use. This invention uses a conductive material for surface modification. The conductive material can accumulate on the inner wall of the pores, making the porous material conductive overall. This allows it to be used in resistive sensing. The conductive material, through the interaction of surface polydopamine and carbon dioxide, can induce changes in the resistance of the flexible material.

[0044] In some embodiments of the present invention, the modified carbon nanomaterial is prepared by grafting alkyl chains onto polydopamine-modified carbon nanomaterial.

[0045] In this invention, dopamine is first polymerized on the surface of carbon nanomaterials to form hydrophilic polydopamine, and then lipophilic alkyl chains are grafted using charge adsorption to obtain modified carbon nanomaterials with dual functions. On the one hand, polydopamine exhibits reversible adsorption with carbon dioxide, causing changes in electrical properties; on the other hand, the modified carbon nanomaterials possess both the hydrophilic portion of polydopamine and the lipophilic portion of the alkyl chains, which can be used to prepare high internal phase emulsion templates for porous material preparation. Furthermore, due to the amphiphilic nature of the nanomaterials, they are extensively adsorbed at the emulsion interface, forming a stable structure embedded in the pore walls of the porous material.

[0046] In some embodiments of the present invention, the elastomer solution is a thermoplastic elastomer solution.

[0047] In some embodiments of the present invention, the thermoplastic elastomer is selected from at least one of polyurethane, styrene-butadiene-styrene block copolymer and thermoplastic polyolefin.

[0048] In some embodiments of the present invention, the organic solvent in the elastomer solution is selected from at least one of cyclohexane, ethyl acetate, and toluene.

[0049] In some embodiments of the present invention, the elastomer reaction solution is selected from at least one of polyurethane reaction solution, silicone rubber reaction solution and acrylate reaction solution.

[0050] In some embodiments of the present invention, the polyurethane reaction solution comprises isocyanate and polyol. Other additives may be selected by those skilled in the art.

[0051] In some embodiments of the present invention, the silicone rubber reaction solution is a platinum curing system, including hydrogen-containing silicone oil and vinyl-containing silicone oil. Other additives can be selected by those skilled in the art.

[0052] In some embodiments of the present invention, the acrylate reaction solution comprises acrylate monomers and a free radical initiator. Other additives may be selected by those skilled in the art.

[0053] In some embodiments of the present invention, the acrylate monomer is selected from at least one of ethyl acrylate and butyl acrylate.

[0054] In some embodiments of the present invention, the free radical initiator is selected from at least one of benzoyl peroxide and azobisisobutyronitrile.

[0055] In some embodiments of the present invention, the surface tension of the high surface tension liquid is greater than 37 mN / m.

[0056] In some embodiments of the present invention, the high surface tension liquid is selected from at least one of water, propylene glycol and ethylene glycol, preferably water.

[0057] In some embodiments of the present invention, in the emulsified emulsion, the elastomer solution or elastomer reactant serves as the continuous phase, and the high surface tension liquid serves as the dispersed phase. The volume fraction of the high surface tension liquid is greater than 75%, preferably greater than 80%, which allows for the formation of a porous structure. If the volume fraction of the high surface tension liquid is too low, a large number of closed pores exist, and the pore throats are barely observable under an electron microscope. The porous material can also be characterized using a permeability test.

[0058] A third aspect of the present invention provides a carbon dioxide detection membrane made of a porous material obtained by the porous material described in the first aspect and the method described in the second aspect.

[0059] According to a particularly preferred embodiment of the present invention, a method for preparing a porous material sensitive to carbon dioxide includes the following steps:

[0060] (1) Preparation of modified nanomaterials

[0061] Carbon nanotubes, graphene, and conductive carbon black powder were dispersed in water containing dopamine and modified polystyrene dispersant by high-speed grinding to obtain a nano-dispersion, wherein the D50 of the nanoparticles was less than 1 μm (preferably less than 300 nm); then ferrous sulfate catalyst was added to the aqueous solution, and the reaction was stirred at room temperature for 1 h to obtain polydopamine-modified carbon nanomaterials; then a certain amount of quaternary ammonium salts containing long-chain alkyl groups (such as hexadecyltrimethylammonium bromide, bis(tetradecyldimethylammonium chloride, etc.) were mixed into the solution, and after stirring for 1 h, polydopamine and alkyl chain modified carbon nanomaterials were obtained;

[0062] (2) Preparation of elastomer solution or elastomer reaction stock solution

[0063] A thermoplastic elastomer (such as polyurethane, styrene-butadiene-styrene block copolymer, thermoplastic polyolefin, etc.) is mixed with an organic solvent (a low surface tension solvent that is immiscible with water, with a surface tension of less than 31 mN / m, selected from cyclohexane, ethyl acetate, toluene, etc.) to obtain an elastomer solution.

[0064] The elastomer reaction raw materials are mixed to obtain the elastomer reaction stock solution; the elastomer reaction stock solution includes polyurethane reaction stock solution, silicone rubber reaction stock solution or acrylate reaction stock solution;

[0065] Polyurethane reaction solutions include isocyanates and polyols; silicone rubber reaction solutions are platinum-cured systems, including hydrogen-containing silicone oils and vinyl-containing silicone oils; acrylate reaction solutions include acrylate monomers (polymers with a glass transition temperature of less than 273K, such as ethyl acrylate, butyl acrylate, etc.) and free radical initiators (benzoyl peroxide, azobisisobutyronitrile, etc.).

[0066] (3) Preparation of porous materials

[0067] The modified carbon nanomaterials obtained in step (1) are ultrasonically dispersed in an elastomer solution or an elastomer reaction stock solution, and a certain volume of water is added. The emulsion is then emulsified using a homogenizer to obtain a stable emulsion with a dispersed phase volume greater than 80%. The elastomer solution or elastomer reaction stock solution is used as the continuous phase and water is used as the dispersed phase. The continuous phase is solidified by heating or freeze-drying and the water is removed to obtain a porous material with a large amount of modified carbon nanomaterials embedded inside.

[0068] The present invention will be described in detail below through embodiments.

[0069] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0070] Example 1

[0071] This embodiment illustrates the preparation of porous materials sensitive to carbon dioxide.

[0072] (1) Modification of conductive carbon black: 100g of bp2000 (Cabot) carbon black was mixed with 50g of byk190 (BYK, modified styrene-maleic anhydride copolymer) and 5g of dopamine, followed by 845g of water. The mixture was ground at 4000rpm for 1h at room temperature to obtain a nano-carbon black dispersion (D50 of 150nm). Ferrous sulfate (0.0001mol / L concentration) was then added to the dispersion and stirred at room temperature for 1h. Finally, 800g of 1% hexadecyltrimethylammonium bromide solution was added to the above liquid, followed by centrifugation and drying at 50℃ to obtain modified conductive carbon black. The centrifuged liquid was subjected to UV-Vis spectrophotometry to obtain the amount of free dopamine and quaternary ammonium salt. The mass of polydopamine was calculated to be 4.3% of the modified conductive carbon black, and the mass of the alkyl chain was 4.8% of the modified conductive carbon black.

[0073] (2) Preparation of porous materials: 1g of modified conductive carbon black was ultrasonically dispersed in 10g of ethyl acrylate containing 1% azobisisobutyronitrile, followed by the addition of 40g of water. The mixture was then emulsified using a homogenizer at 15000rpm for 5min to obtain a high internal phase emulsion. This emulsion was coated onto a polyethylene sheet with a thickness of 1mm and cured at 80℃ for 8h to obtain a membrane-like porous material. In the membrane-like porous material, the mass ratio of modified conductive carbon black to the polyethyl acrylate porous matrix was 1:10.

[0074] Its wall structure is as follows Figure 1 and Figure 2 As shown, the prepared porous material has a through-pore structure with a large number of carbon nanomaterials embedded in the pore walls, which can serve as gas adsorption sites.

[0075] Example 2

[0076] Porous materials were prepared according to the method of Example 1, except that the 5g of dopamine in step (1) was replaced with 3.4g, and 550g of 1% hexadecyltrimethylammonium bromide solution was added. In the obtained modified conductive carbon black, the mass of polydopamine was 3% of the modified conductive carbon black, and the mass of the alkyl chain was 3.5% of the modified conductive carbon black.

[0077] Example 3

[0078] The porous material was prepared according to the method of Example 1, except that the 1g of modified conductive carbon black in step (2) was replaced with 1.6g. In the porous material, the mass ratio of modified conductive carbon black to polyethyl acrylate porous matrix was 16:100.

[0079] Example 4

[0080] Porous materials were prepared according to the method of Example 1, except that the 5g of dopamine in step (1) was replaced with 11.8g. In the resulting modified conductive carbon black, the mass of polydopamine was 10% of the modified conductive carbon black.

[0081] Example 5

[0082] (1) Modification of conductive carbon nanotubes: 100g of GPX702 (Cabot) carbon nanotubes were mixed with 30g of TEGO750W / 760W (two dispersants in a 1:1 mass ratio, TEGO) and 10g of dopamine, followed by 860g of water. The mixture was ground at 4500rpm for 4 hours at room temperature to obtain a carbon nanotube dispersion (D50 of 300nm). Ferrous sulfate (0.0002mol / L concentration) was then added to the dispersion, and the mixture was stirred at room temperature for 1 hour. Finally, 950g of a 2% dic(decanedioyl)dimethylammonium chloride solution was added to the above liquid, followed by centrifugation and drying at 50℃ to obtain modified conductive carbon nanotubes. The mass of polydopamine was 8.9% of the modified conductive carbon nanotubes; the mass of the alkyl chain was 16% of the modified conductive carbon nanotubes.

[0083] (2) Preparation of porous materials: 1g of modified conductive carbon nanotubes were ultrasonically dispersed in vinyl silicone oil, and then hydrogen-containing silicone oil was added and mixed to obtain 26g of reaction liquid with dispersed carbon nanotubes. Subsequently, 100g of ethylene glycol was added, and the mixture was emulsified at 20,000 rpm for 10 min using a homogenizer to obtain a high internal phase emulsion. The emulsion was coated on a polyethylene plate with a coating thickness of 1mm and cured at 80℃ for 24h to obtain a membrane porous material. In the membrane porous material, the mass ratio of modified conductive carbon nanotubes to silicone rubber porous matrix was 1:25.

[0084] Comparative Example 1

[0085] The material was prepared according to the method of Example 1, except that in step (2), 1g of modified conductive carbon black was ultrasonically dispersed in 10g of ethyl acrylate containing 1% azobisisobutyronitrile for polymerization to obtain a non-porous material with a thickness of 1mm.

[0086] Comparative Example 2

[0087] The material was prepared according to the method of Example 1, except that dopamine and ferrous sulfate were not added in step (1).

[0088] Comparative Example 3

[0089] The material was prepared according to the method of Example 1, except that no quaternary ammonium salt was added in step (1). Due to the poor oleophilicity of the modified carbon black, a stable emulsion could not be obtained, and only a non-porous material with a thickness of 1 mm could be obtained.

[0090] Comparative Example 4

[0091] The modified conductive material dispersion was prepared according to the method described in Example 5, without the need for a final drying step. A commercially available open-cell porous polyurethane material with an average pore size of approximately 200 μm was selected and cut into 10*10*1 mm shapes. These shapes were then immersed in the dispersion at room temperature for 24 hours. Finally, the samples were removed and vacuum-dried at 50°C for 48 hours.

[0092] Comparative Example 5

[0093] The porous material was prepared according to the method of Example 1, except that the 1g of modified conductive carbon black in step (2) was replaced with 0.1g. In the porous material, the mass ratio of modified conductive carbon black to polyethyl acrylate porous matrix was 1:100.

[0094] Its wall structure is as follows Figure 3 As shown, conductive carbon nanoparticles can be seen on some of the wall surfaces. Due to the limited number of adsorption sites, the adsorption saturation concentration is low.

[0095] Test Example 1

[0096] Carbon dioxide adsorption test method:

[0097] A 10*10*1mm membrane-like porous material was placed in a sealed container, and positive and negative electrodes were led out from the cross-sections on both sides of the material to the outside of the container. The resistance value was measured with different concentrations of carbon dioxide gas (2-8%) and the resistance value was calculated to be the same as that without gas.

[0098] Sensitivity refers to the change in resistance per unit change in concentration.

[0099] Table 1 shows the ratio of the rate of change of resistance at a sensitivity of 8% carbon dioxide concentration to the carbon dioxide concentration (8%).

[0100] The results are shown in Table 1.

[0101] Table 1

[0102]

[0103]

[0104] The results in Table 1 show that the porous materials in Examples 1-5 exhibit high sensitivity (large resistance change rate) and a linear increase in resistance value within the test range, indicating a wide detection concentration range. Example 3, due to its small pore size and high content of modified carbon nanoparticles, shows relatively high sensitivity. Example 4, due to its high polydopamine content and numerous adsorption sites, also exhibits relatively high sensitivity. Example 2, with its lower polydopamine content, has slightly lower sensitivity compared to the other examples. Example 5, with its lower content of modified carbon nanoparticles, also has slightly lower sensitivity.

[0105] Comparative Example 1 has a non-porous membrane structure and saturates at very low concentrations. Comparative Example 2, without polydopamine modification, lacks adsorption binding sites for carbon dioxide, resulting in poor response to carbon dioxide concentration. Comparative Example 3, without alkyl chain modification, produces a non-oleophilic modified conductive carbon black that cannot form an emulsion, lacks a porous membrane structure, and saturates at very low concentrations. Comparative Example 5 has a low content of modified carbon nanoparticles, large pore size, and few adsorption sites, thus exhibiting adsorption saturation.

[0106] Test Example 2

[0107] The samples from Example 5 and Comparative Example 4 were subjected to tensile fatigue tests with a tensile rate of 10%, a fatigue cycle of 100,000 times, and a frequency of 1 Hz. The resistive response of adsorbed carbon dioxide before and after fatigue was measured.

[0108]

[0109]

[0110] According to the results in the table, the response characteristics of the porous membrane material prepared in Example 5 remained basically stable before and after fatigue. In Comparative Example 4, because the modified carbon nanomaterials only bonded to the wall surface through physical non-covalent interactions, the affinity was low, resulting in a small amount of modified carbon nanomaterials on the pore wall surface, leading to adsorption saturation under high concentrations of carbon dioxide. After fatigue, a large amount of modified carbon nanomaterials detached, making adsorption more prone to saturation.

[0111] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A porous material sensitive to carbon dioxide, characterized in that, The porous material includes a porous elastomer matrix and modified carbon nanomaterials embedded in the pore walls of the porous elastomer matrix; The porous elastomer matrix has a through-hole structure; The modified carbon nanomaterial is a carbon nanomaterial that has been modified with both polydopamine and alkyl chains.

2. The porous material according to claim 1, wherein, The porous elastomer matrix is ​​selected from at least one of polyurethane porous matrix, styrene-butadiene-styrene block copolymer porous matrix, polyolefin porous matrix, silicone rubber porous matrix and polyacrylate porous matrix.

3. The porous material according to claim 1 or 2, wherein, The carbon nanomaterial is selected from at least one of carbon nanotubes, graphene, and conductive carbon black. Preferably, the specific surface area of ​​the modified carbon nanomaterial is greater than 100 g / m². 2 Preferably greater than 200g / m 2 ; Preferably, the mass of the polydopamine is 3-10% of the modified carbon nanomaterial, more preferably 4.3-8.9%; Preferably, the mass of the alkyl chain is 3.5-16% of the modified carbon nanomaterial, more preferably 4.8%; Preferably, the alkyl chain comprises 2-3 short-chain alkyl chains and 1-2 long-chain alkyl chains; Preferably, the short-chain alkyl chain has 1-2 carbon atoms; Preferably, the long-chain alkyl chain has 8-18 carbon atoms, more preferably 10-16; Preferably, the alkyl chain is derived from at least one of hexadecyltrimethylammonium bromide, bis(tetradecyl)dimethylammonium chloride, dodecyltriethylammonium chloride, and bis(decyl)dimethylammonium chloride.

4. The porous material according to any one of claims 1-3, wherein, The mass ratio of the modified carbon nanomaterial to the porous elastomer matrix is ​​4-16:100, preferably 8-12:100, and more preferably 10:100; Preferably, the pore size of the porous material is 5-400 μm, and more preferably 20-200 μm.

5. A method for preparing a porous material according to any one of claims 1-4, characterized in that, The method includes: mixing, emulsifying, and solidifying modified carbon nanomaterials, an elastomer solution or an elastomer reaction stock solution, and a high surface tension liquid to obtain the porous material.

6. The method according to claim 5, wherein, The modified carbon nanomaterials were prepared by grafting alkyl chains onto polydopamine-modified carbon nanomaterials.

7. The method according to claim 5 or 6, wherein, The elastomer solution is a thermoplastic elastomer solution; Preferably, the thermoplastic elastomer is selected from at least one of polyurethane, styrene-butadiene-styrene block copolymer, and thermoplastic polyolefin; Preferably, the organic solvent in the elastomer solution is selected from at least one of cyclohexane, ethyl acetate, and toluene; Preferably, the elastomer reaction solution is selected from at least one of polyurethane reaction solution, silicone rubber reaction solution, and acrylate reaction solution; Preferably, the polyurethane reaction solution comprises isocyanate and polyol; Preferably, the silicone rubber reaction solution is a platinum curing system, including hydrogen-containing silicone oil and vinyl-containing silicone oil; Preferably, the acrylate reaction solution comprises acrylate monomers and a free radical initiator; Preferably, the acrylate monomer is selected from at least one of ethyl acrylate and butyl acrylate; Preferably, the free radical initiator is selected from at least one of benzoyl peroxide and azobisisobutyronitrile.

8. The method according to any one of claims 5-7, wherein, The surface tension of the high surface tension liquid is greater than 37 mN / m; Preferably, the high surface tension liquid is selected from at least one of water, propylene glycol, and ethylene glycol, with water being the most preferred.

9. The method according to any one of claims 5-8, wherein, In the emulsified emulsion, the elastomer solution or elastomer reaction stock solution serves as the continuous phase, and the high surface tension liquid serves as the dispersed phase, with the volume of the high surface tension liquid being greater than 75%, preferably greater than 80%.

10. A carbon dioxide detection membrane made of the porous material according to any one of claims 1-4 and the porous material obtained by the method according to any one of claims 5-9.

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