Preparation method and application of flexible porous membrane capable of identifying polar and non-polar gases

Abstract

The invention discloses a preparation method and application of a flexible porous membrane capable of identifying polar and non-polar gases, and the preparation method comprises the following steps: step 1, uniformly stirring and mixing a prepolymer and a curing agent, adding a mixture of carbon black and a sacrificial template, ultrasonically and uniformly mixing, vacuumizing to remove bubbles, and heating and curing to obtain a compound of a membrane and the sacrificial template; 2, removing the sacrificial template in the compound by using a template remover, cleaning by using a cleaning agent, and drying to obtain a flexible porous PDMS substrate; and step 3, placing the flexible porous PDMS substrate in a plasma cleaning instrument for radio frequency treatment, placing the flexible porous PDMS substrate subjected to radio frequency treatment in a cross-linking agent-containing solvent, standing in a dark place, cleaning, and drying to obtain the flexible porous membrane. According to the preparation method, carbon powder is introduced to enhance an electric signal after being in contact with gas, molecular chains containing F / H are connected into the surface and holes of the membrane through self-assembly, and due to the difference of F / H electronegativity, corresponding electric signals are presented for gas molecules with different polarities for people to distinguish the gas.

Description

Technical Field

[0001] This invention belongs to the field of gas sensing technology, specifically relating to a method for preparing and applying a flexible porous membrane capable of identifying polar and non-polar gases. Background Technology

[0002] Most existing gas-sensitive materials are based on metal oxides and their composites. From a preparation perspective, the synthesis steps of these materials are cumbersome, requiring a significant amount of time and effort. Furthermore, most of the final synthesized materials lack flexibility, which greatly limits their practical applications. Porous polydimethylsiloxane (PDMS), on the other hand, is a material widely used by researchers due to its recognized flexibility. Importantly, its preparation method is simple and efficient.

[0003] From the perspective of gas identification, existing gas-sensitive materials rely on changes in resistance and charge accumulation, which suffer from low sensitivity and recognition accuracy, and limited gas selectability. In complex gas environments, this limited selection makes it difficult to effectively identify multiple gases. In recent years, researchers have improved gas identification performance through surface modification and physical doping.

[0004] CN 112980022A discloses a porous carbon capsule-based / polydimethylsiloxane composite flexible membrane, its preparation method, and its application. The preparation method includes preparing a carbon-coated catalyst by reacting a catalyst with a carbon source gas at high temperature, then repeatedly washing the catalyst in an acidic solution to obtain hollow porous carbon capsules, mixing and grinding the capsules with an auxiliary pore-forming agent to obtain a mixed powder, sieving the mixed powder onto the surface of a polydimethylsiloxane wet membrane, curing it, and then immersing it in an aqueous solution to finally obtain a porous carbon capsule-based / polydimethylsiloxane composite flexible membrane. However, this method does not disclose a method for synthesizing molecules with significant pore size differences using different sacrificial templates or a method for utilizing self-assembled links of molecules with different electronegative functional groups. The resulting composite flexible membrane cannot effectively identify polar and non-polar gases.

[0005] Most existing gas identification devices have complex structures and cannot operate independently without a battery. Notably, there is currently no established theory for identifying specific gases based on the electrical signals generated by friction between gases of different polarities due to differences in the electronegativity of functional groups. Nanogenerators, however, offer advantages such as device simplicity, diverse material choices, and the ability to operate independently with their own power, providing a perfect application platform for gas identification through friction. This paper presents the fabrication and application of a flexible porous membrane capable of identifying polar / non-polar gases. Summary of the Invention

[0006] To address the aforementioned problems, this invention discloses a method for preparing a flexible porous membrane capable of identifying polar and non-polar gases, and its application, relating to the field of gas sensing. The flexible porous membrane is characterized by synthesizing a PDMS substrate with composite carbon powder of different pore sizes using a sacrificial template method, and then performing self-assembly on this substrate to form the flexible porous membrane.

[0007] According to a first aspect of the present invention, a method for preparing a flexible porous membrane capable of identifying polar and nonpolar gases is provided, comprising the following steps: Step 1: Stir the prepolymer and curing agent to mix well, add the mixture of carbon black and sacrificial template, mix ultrasonically, remove air bubbles by vacuuming, and heat to cure to obtain the composite of film and sacrificial template. Step 2: Remove the sacrificial template in the composite using a template remover, clean with a cleaning agent, and dry to obtain a flexible porous PDMS substrate; Step 3: Place the flexible porous PDMS substrate in a plasma cleaner for radio frequency, and then place the radio-treated flexible porous PDMS substrate in a solvent containing a crosslinking agent, keep it in the dark, clean it, and dry it to obtain a flexible porous membrane.

[0008] Based on the above technical solution, the mass ratio of prepolymer, curing agent, and carbon black in step 1 is 10~15:1:0.55~0.8; The mass ratio of carbon black to sacrificial template in step 1 is 0.5~0.8:5~12; The prepolymer is polydimethylsiloxane; The sacrificial template is a mixture of granulated sugar and powdered sugar or commercially available nickel foam, wherein the mass ratio of granulated sugar to powdered sugar in the mixture is 0.5~1:0.5~1; the commercially available nickel foam has a size of 30*30mm~70*70mm and a thickness of 5~20mm.

[0009] Based on the above technical solution, the ultrasonic mixing time in step 1 is 40~60min, and the vacuuming time is 30~40min.

[0010] Based on the above technical solution, the conditions for heat curing in step 1 are as follows: When the sacrificial template is a mixture of granulated sugar and powdered sugar, the heating and curing time is 40-60 minutes and the heating and curing temperature is 90-100°C. When the sacrificial template is commercially available nickel foam, the heating and curing time is 30-40 minutes, and the heating and curing temperature is 160-170°C.

[0011] Based on the above technical solution, the template eliminator is water or ferric chloride solution; When the template eliminator is a ferric chloride solution, the concentration is 0.8M~1.5M; The mass ratio of the template eliminator to the complex in step 2 is 30~40:8~15.

[0012] Based on the above technical solution, the cleaning agent in step 2 is water or ethanol, and the amount added is 300-350% of the template eliminator; The pore size of the flexible porous PDMS substrate obtained in step 2 is 30um~500um.

[0013] Based on the above technical solution, the radio frequency conditions in step 3 are as follows: The intensity of the radio frequency is 90%~100%; The duration of the radio frequency is 180~200s.

[0014] Based on the above technical solution, the crosslinking agent in the solvent containing the crosslinking agent in step 3 is trichloro(1H,1H,2H,2H-tetrafluoron-octyl)silane or n-octyltrichlorosilane, and the solvent is N,N-dimethylformamide, wherein the mass ratio of solvent to crosslinking agent is 7~7.5:1; The time for keeping the plant in the dark as described in step 3 is 48~72 hours; The cleaning process described in step 3 involves immersing the flexible porous PDMS substrate, which has been kept in the dark and allowed to stand, in water and ethanol for 1-5 minutes, and repeating this process 2-4 times.

[0015] Based on the above technical solution, the drying conditions in steps 2 and 3 are as follows: The drying temperature is 20~40℃; The drying time is 12-20 hours.

[0016] According to another aspect of the present invention, an application of a flexible porous membrane in the identification of polar and non-polar gases is provided. Conductive aluminum paper is attached to the bottom of the flexible porous membrane, and gases of different polarities are pushed in to form different voltage intensities, thereby identifying polar and non-polar gases.

[0017] Based on the above technical solutions, the flexible porous membrane is a 13F-C-PDMS complex with nickel foam, a 13F-C-PDMS complex with mixed sugars, a 13H-C-PDMS complex with nickel foam, and a 13H-C-PDMS complex with mixed sugars. The gases of different polarities are selected from at least one of water vapor, nitrogen, ethanol, and ammonia, preferably nitrogen and water vapor; The voltage intensity is formed by at least one of water vapor-sugar 13F, water vapor-nickel 13F, water vapor-sugar 13H, water vapor-nickel 13H, nitrogen-sugar 13F, nitrogen-nickel 13F, nitrogen-sugar 13H, and nitrogen-nickel 13H.

[0018] Beneficial effects The technical solution disclosed in this invention uses PDMS as a substrate and a template-free synthesis method, with the addition of an appropriate amount of carbon powder, to obtain flexible porous membranes with different pore sizes. These pores greatly increase the specific surface area of ​​the material, and the introduction of carbon powder further enhances the electrical signal after contact with gas. For recognition, F / H-containing molecular chains are incorporated into the membrane surface and pores through self-assembly. Due to the difference in electronegativity between F and H, these molecular chains will exhibit corresponding electrical signals to distinguish gases of different polarities, such as ethanol, water vapor, nitrogen, and ammonia. This method of gas recognition based on electronegativity differences is rare in the current environment. Importantly, because the amount of gas passing through different pore sizes varies, coupled with the difference in specific surface area, gas-solid interactions, and the different electrical signals generated by functional group friction, the function of recognizing multiple gases of different polarities can be achieved. Attached Figure Description

[0019] Figure 1 Scanning electron microscope image of the flexible porous membrane of 13F-C-PDMS and mixed sugar complex prepared in Example 1 of this invention; Figure 2 Scanning electron microscope image of the flexible porous membrane of 13H-C-PDMS and mixed sugar complex prepared in Example 2 of this invention; Figure 3 Scanning electron microscope image of the flexible porous membrane of 13F-C-PDMS and nickel foam composite prepared in Example 3 of this invention; Figure 4 Scanning electron microscope image of the flexible porous membrane of 13H-C-PDMS and nickel foam composite prepared in Example 4 of this invention; Figure 5 A scanning electron microscope image of the flexible porous PDMS substrate for the sugar template prepared in Example 1 of this invention; Figure 6 A scanning electron microscope image of the nickel template flexible porous PDMS substrate prepared in Example 3 of this invention; Figure 7 The energy dispersive spectroscopy (EDS) results are shown for the flexible porous membrane of 13F-C-PDMS and mixed sugar complex prepared in Example 1 of this invention. Figure 8 The energy dispersive spectroscopy (EDS) results are shown for the flexible porous membrane of 13H-C-PDMS and mixed sugar complex prepared in Example 2 of this invention. Figure 9 The energy dispersive spectroscopy (EDS) results are shown for the flexible porous membrane of 13F-C-PDMS and nickel foam composite prepared in Example 3 of this invention. Figure 10 The energy dispersive spectroscopy (EDS) results are shown for the flexible porous membrane of 13H-C-PDMS and nickel foam composite prepared in Example 4 of this invention. Figure 11 This is a schematic diagram showing the contact between 13F-C-PDMS and a flexible porous membrane of nickel foam composite and water vapor, as described in Application Example 1 of the present invention. Figure 12 This is a schematic diagram showing the contact between 13F-C-PDMS and the flexible porous membrane of the mixed sugar complex and water vapor, as described in Application Example 2 of the present invention; Figure 13 This is a schematic diagram showing the contact between 13F-C-PDMS and the flexible porous membrane of the mixed sugar complex and nitrogen gas, as described in Application Example 5 of the present invention. Figure 14 This is a schematic diagram showing the contact between the 13F-C-PDMS and the nickel foam composite flexible porous membrane described in Application Example 6 of the present invention and nitrogen gas; Figure 15 The voltage intensity change of the flexible porous membrane of 13F-C-PDMS and nickel foam composite described in Application Example 1 of this invention after contact with water vapor; Figure 16 The voltage intensity change of the flexible porous membrane of 13F-C-PDMS and mixed sugar complex described in Application Example 2 of this invention after contact with water vapor; Figure 17 The voltage intensity change of the flexible porous membrane of 13H-C-PDMS and nickel foam composite described in Application Example 3 of this invention after contact with water vapor; Figure 18 The voltage intensity change of the flexible porous membrane of 13H-C-PDMS and mixed sugar complex described in Application Example 4 of this invention after contact with water vapor; Figure 19 The voltage intensity of the flexible porous membrane of 13F-C-PDMS and mixed sugar complex described in Application Example 5 of this invention after contact with nitrogen gas; Figure 20 The voltage intensity change of the flexible porous membrane of 13F-C-PDMS and nickel foam composite described in Application Example 6 of this invention after contact with nitrogen gas; Figure 21 The voltage intensity change of the flexible porous membrane of 13H-C-PDMS and mixed sugar complex described in Application Example 7 of this invention after contact with nitrogen gas; Figure 22 The voltage intensity change of the flexible porous membrane of 13H-C-PDMS and nickel foam composite described in Application Example 8 of the present invention after contact with nitrogen gas. Detailed Implementation

[0020] To make the objectives and technical solutions of this invention clearer, the following embodiments are provided for further explanation. However, the scope of protection of this invention is not limited to these embodiments; the embodiments are merely for illustrative purposes. Those skilled in the art should understand that any changes or equivalent substitutions that do not depart from the concept of this invention are included within the scope of protection of this invention.

[0021] Unless otherwise specified, all reagents and raw materials used in this invention are obtained through purchase.

[0022] The polydimethylsiloxane (PDMS prepolymer, SYLGARD™ 184 SiliconeElastomer Base) used in the preparation example of this invention was purchased from Dow Corning. In addition, the curing agent (SYLGARD™ 184 SiliconeElastomer Curing Agent) was used in conjunction with it. The granulated sugar, powdered sugar and nickel foam were purchased from commercial channels. The nickel foam had a size of 80mm~100mm and a thickness of 5mm and was purchased from Silverfloat Aluminum Foam Company.

[0023] Preparation Example 1 Step 1, Preparation of the mixed substrate: Mix 2g of polydimethylsiloxane (PDMS prepolymer) with 0.2g of curing agent until homogeneous. Simultaneously, mix 6g of granulated sugar, 6g of caster sugar, and 0.11g of carbon black until homogeneous, ensuring the carbon black adheres to the sugar surface. Pour the mixed sugar / carbon black into the above-mentioned PDMS mixture, ultrasonically mix for 1 hour, then transfer to a vacuum drying oven, evacuate for 30 minutes to remove air bubbles, and heat at 90℃ for 1 hour to cure, obtaining the PDMS / sugar complex.

[0024] Step 2, Template Removal: 15g of the PDMS / glycan complex obtained in Step 1 was soaked in 40ml of deionized water for 24 hours to dissolve the sugar template. Residual sugar solution was removed by sonication in anhydrous ethanol for 10 minutes. The substrate was then dried at room temperature for 12 hours to obtain a flexible porous PDMS substrate with a sugar template (5×5cm, 40µm pore size). The porous PDMS substrate is shown in the scanning electron microscope image. Figure 5 The energy spectrum data are shown in Table 1. Step 3, Radio Frequency and Crosslinking Treatment: The sugar template flexible porous PDMS substrate obtained in Step 2 is placed in a plasma cleaner and radio frequency is applied for 200 seconds to obtain a radio frequency-treated porous PDMS substrate; 15 ml of anhydrous DMF and 0.2 ml of crosslinking agent trichloro(3,3,3-tridecylfluoropropyl)silane (C3H4C) are added. l3F3Si, 13F) was ultrasonicated for 5 min and poured into a ground-glass sealed bottle. The radiofrequency-treated porous PDMS substrate was then placed horizontally in the bottle in the dark for 72 h for crosslinking. After standing, the crosslinked porous PDMS substrate was ultrasonically cleaned in deionized water for 1 min, followed by ultrasonication twice with ethanol for 1 min each time. A flexible porous membrane (pore size 40 μm) of 13F-C-PDMS and mixed sugar complex was obtained. Its scanning electron microscope image is shown below. Figure 1 The energy spectrum test results are as follows Figure 7 As shown, the sugar, acting as a sacrificial template, has provided interconnected pores for PDMS, and 13F has successfully self-assembled on the porous PDMS substrate, exhibiting voltage intensity variation. The energy dispersive spectroscopy data of the flexible porous membrane of the 13F-C-PDMS and mixed sugar complex are shown in Table 2.

[0025] Table 1. Scanning electron microscopy (SEM) energy dispersive spectroscopy data of the flexible porous PDMS substrate prepared in Example 1.

[0026] Table 2. Scanning electron microscopy (SEM) energy dispersive spectroscopy (EDS) data of the flexible porous membrane prepared in Example 1, consisting of 13F-C-PDMS and mixed sugar complex.

[0027] Preparation Example 2 The difference from Preparation Example 1 is that the crosslinking agent used in step 3 is n-octyltrichlorosilane (C8H2O). 17 C l3 Si, i.e., 13H), the remaining steps are the same as in Preparation Example 1, to obtain a flexible porous membrane (pore size 40 μm) of 13H-C-PDMS and mixed sugar complex. The scanning electron microscope image of the porous membrane is shown below. Figure 2 The energy spectrum test results are as follows Figure 8 As shown, the sugar, acting as a sacrificial template, has provided interconnected pores for PDMS, and 13H has successfully self-assembled on the porous PDMS substrate, exhibiting voltage intensity variation. The energy dispersive spectroscopy data of the flexible porous membrane of the 13H-C-PDMS and mixed sugar complex are shown in Table 3.

[0028] Table 3. Scanning electron microscopy (SEM) data of the flexible porous membrane containing the 13H-C-PDMS and mixed sugar complex prepared in Example 2.

[0029] Preparation Example 3 Step 1, Preparation of mixed substrate: Mix 5g of polydimethylsiloxane (PDMS prepolymer) with 0.5g of curing agent, then add 0.275g of carbon black, ultrasonically mix for 1h, inject into nickel mold, transfer to vacuum drying oven, vacuum for 30min to allow the colloid to be tightly adsorbed in the holes of nickel mold, and heat at 160℃ for 0.5h to cure to obtain PDMS / nickel mesh composite.

[0030] Step 2, Template Removal: The PDMS / nickel mesh mixture obtained in Step 1 was immersed in a template removal solution of 30 wt.% FeCl3 and 1M HCl for 72 h. After immersion, it was transferred to anhydrous ethanol and ultrasonically cleaned twice for 30 min each time, and then dried at room temperature for 12 h. This yielded a nickel-templated flexible porous PDMS substrate (5×5 cm, pore size 300 μm). The scanning electron microscope image of the porous PDMS substrate is shown below. Figure 6 The energy spectrum data are shown in Table 4. Step 3, Radio Frequency and Crosslinking Treatment: The porous PDMS substrate obtained in Step 2 is placed in a plasma cleaner and subjected to radio frequency for 200 seconds to obtain a flexible porous PDMS substrate after radio frequency treatment. 15 ml of anhydrous DMF and 0.2 ml of crosslinking agent trichloro(3,3,3-tridecylfluoropropyl)silane (C3H4C) are added. l3 F3Si, 13F) was ultrasonicated for 5 min and poured into a ground glass bottle with a sealed ground glass joint. The radiofrequency-treated porous PDMS substrate was then placed horizontally in the bottle in the dark for 72 h for crosslinking. After standing, the crosslinked porous PDMS substrate was ultrasonically cleaned in deionized water for 1 min, followed by ultrasonication twice with ethanol for 1 min each time. A flexible porous membrane (pore size 300 μm) of 13F-C-PDMS and nickel foam composite was obtained. Scanning electron microscopy showed… Figure 3 The energy dispersive spectroscopy (EDS) results are shown in [link to EDS test results]. Figure 9 This indicates that nickel, as a sacrificial template, has provided interconnected pores for PDMS. These pores are relatively large relative to the porous PDMS substrate synthesized using the nickel template, and 13F has successfully self-assembled on the porous PDMS substrate, exhibiting voltage intensity variation. The energy dispersive spectroscopy data of the flexible porous membrane of the 13F-C-PDMS and nickel foam composite are shown in Table 5.

[0031] Table 4. Scanning electron microscopy (SEM) energy dispersive spectroscopy (EDS) data of the nickel template flexible porous PDMS substrate prepared in Example 3.

[0032] Table 5. Scanning electron microscopy (SEM) energy dispersive spectroscopy (EDS) data of the flexible porous membrane of 13F-C-PDMS-nickel foam composite prepared in Preparation Example 3.

[0033] Preparation Example 4 The difference from Preparation Example 3 is that the crosslinking agent used in step 3 is n-octyltrichlorosilane (C8H2O). 17 C l3 Si (i.e., 13H), the remaining steps are the same as in Preparation Example 1, to obtain a flexible porous membrane of 13H-C-PDMS and nickel foam composite, the scanning electron microscope image of which is shown below. Figure 4 The energy spectrum test results are as follows Figure 10 As shown, nickel, as a sacrificial template, has provided interconnected pores for PDMS, and 13H has successfully self-assembled on the porous PDMS substrate, exhibiting voltage intensity variation. The scanning electron microscope energy dispersive spectroscopy data of the porous membrane of the 13H-C-PDMS and nickel foam composite are shown in Table 6.

[0034] Table 6. Scanning electron microscopy (SEM) energy dispersive spectroscopy (EDS) data of the flexible porous membrane of 13H-C-PDMS-nickel foam composite prepared in Preparation Example 4.

[0035] Application Example 1 The bottom of the flexible porous membrane of 13F-C-PDMS and nickel foam composite obtained in Example 3 was prepared by attaching aluminum foil as a conductive layer. Water vapor was drawn out using a syringe, and then gas was expelled to form an airflow in contact with the flexible porous membrane of 13F-C-PDMS and nickel foam composite. A schematic diagram of the contact is shown below. Figure 11 The gas injection time was 0.07 s. Due to the relatively large pore size of the flexible porous membrane of the 13F-C-PDMS / nickel foam composite, and the large voltage generated by the self-assembled fluorine-containing functional groups after contact and friction with the polar gas, the voltage intensity generated by this porous membrane due to contact with the gas flow was 2.11 V. The voltage intensity variation is shown in [the figure]. Figure 15 .

[0036] Application Example 2 The difference from Application Example 1 is that the flexible porous membrane of the 13F-C-PDMS and nickel foam composite obtained in Preparation Example 3 is replaced with the flexible porous membrane of the 13F-C-PDMS and mixed sugar composite prepared in Preparation Example 1. Gas is then introduced to form an airflow that contacts the flexible porous membrane of the sugar 13F-C-PDMS and mixed sugar composite. A schematic diagram of the contact is shown below. Figure 12 Because the pores of the 13F-C-PDMS / mixed sugar complex flexible porous membrane are smaller than those of the 13F-C-PDMS / mixed sugar complex flexible porous membrane, resulting in a relatively smaller surface area, the voltage intensity generated by the contact airflow friction of this porous membrane is 1.80V. The voltage change is shown in [the table / reference needed]. Figure 16 .

[0037] Application Example 3 The difference from Application Example 1 is that the flexible porous membrane of the 13F-C-PDMS and nickel foam composite prepared in Preparation Example 3 is replaced with the flexible porous membrane of the 13H-C-PDMS and nickel foam composite prepared in Preparation Example 4. Gas flow is then introduced to contact the flexible porous membrane of the 13H-C-PDMS and nickel foam composite. Since the voltage generated by the friction between the hydrogen-containing functional groups and the polar gas is relatively smaller than that of the fluorine-containing functional groups, the voltage intensity generated by the friction of the contact gas flow in this porous membrane is 1.45V. The voltage change is shown in [the figure]. Figure 17 .

[0038] Application Example 4 The difference from Application Example 1 is that the flexible porous membrane of the 13F-C-PDMS and nickel foam composite prepared in Preparation Example 3 is replaced with the flexible porous membrane of the 13H-C-PDMS and mixed sugar composite prepared in Preparation Example 2. Gas is then introduced to form an airflow that contacts the flexible porous membrane of the 13H-C-PDMS and mixed sugar composite. Because the pores of the flexible porous membrane of the 13H-C-PDMS and mixed sugar composite are smaller than those of the flexible porous membrane of the 13H-C-PDMS and nickel foam composite, the relative surface area is reduced. The voltage intensity generated by the friction of the contact airflow in this porous membrane is 0.67V. The voltage intensity variation is shown in [the figure]. Figure 18 .

[0039] Application Example 5 The bottom of the flexible porous membrane of 13F-C-PDMS and mixed sugar complex obtained in Example 1 was prepared by attaching aluminum foil as a conductive layer. Nitrogen gas was drawn in with a syringe and then expelled to form an airflow in contact with the flexible porous membrane of 13F-C-PDMS and mixed sugar complex. A schematic diagram of the contact is shown below. Figure 13 The gas introduction time was 0.07 s. Because nitrogen molecules are smaller than water molecules, the porous PDMS substrate synthesized using the sugar template has some pores with smaller pore sizes compared to that synthesized using the nickel template. This results in some smaller pores being able to accommodate nitrogen molecules, while water molecules, due to their relatively larger molecular size, cannot enter. This ultimately leads to a reduced relative contact area, and consequently, the voltage intensity generated by the contact gas flow friction of the porous membrane is higher than in Application Example 4, reaching 0.83 V. The voltage intensity variation is shown in [Figure 4]. Figure 19 Furthermore, based on this, the porous PDMS substrates synthesized using the two templates exhibit a different voltage intensity order for nonpolar gases compared to polar gases. It can be seen that the porous PDMS substrate synthesized using the sugar template is superior to that synthesized using the nickel template.

[0040] Application Example 6 The difference from Application Example 5 is that the flexible porous membrane of 13F-C-PDMS and mixed sugar complex prepared in Preparation Example 1 is replaced with the flexible porous membrane of 13F-C-PDMS and nickel foam complex prepared in Preparation Example 3. Gas is then introduced to form an airflow in contact with the flexible porous membrane of 13F-C-PDMS and nickel foam complex. A schematic diagram of the contact is shown below. Figure 14 The voltage intensity generated by this porous membrane due to contact with the airflow is 0.56V. The voltage change is shown in [the figure]. Figure 20 .

[0041] Application Example 7 The difference from Application Example 5 is that the flexible porous membrane of the 13F-C-PDMS and mixed sugar complex prepared in Preparation Example 1 was replaced with the flexible porous membrane of the 13H-C-PDMS and mixed sugar complex prepared in Preparation Example 2, and the gas was pushed out to form an airflow in contact with the 13H-C-PDMS (mixed sugar). The voltage intensity generated by the friction of the contact airflow in this porous membrane is 0.35V, such as... Figure 21 .

[0042] Application Example 8 The difference from Application Example 5 is that the flexible porous membrane of the 13F-C-PDMS and mixed sugar complex prepared in Preparation Example 1 was replaced with the flexible porous membrane of the 13H-C-PDMS and nickel foam complex prepared in Preparation Example 4. Gas was then introduced to form an airflow that contacted the 13H-C-PDMS and nickel foam complex flexible porous membrane. The voltage intensity generated by the friction of this porous membrane due to the contact airflow was 0.25V. The voltage intensity variation is shown in […]. Figure 22 .

[0043] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for producing a flexible porous membrane capable of discriminating between polar and nonpolar gases, characterized by, It comprises the following steps: Step 1: stirring and mixing the prepolymer with the curing agent, adding the mixture of carbon black and sacrificial template, ultrasonic mixing, vacuum degassing, heating and curing to obtain a composite of the film and the sacrificial template; Step 2: removing the sacrificial template in the composite by using a template remover, washing with a cleaning agent and drying to obtain a flexible porous PDMS substrate; Step 3: placing the flexible porous PDMS substrate in a plasma cleaner for radio frequency, placing the flexible porous PDMS substrate after radio frequency in a solvent containing a crosslinking agent, avoiding light, standing, washing and drying to obtain a flexible porous film.

2. The production method according to claim 1, characterized by, The mass ratio of the prepolymer, the curing agent and the carbon black in step 1 is 10-15:1:0.5-0.8; The mass ratio of the carbon black and the sacrificial template in step 1 is 0.5-0.8:5-12; The prepolymer is polydimethylsiloxane; The sacrificial template is a mixture of white granulated sugar and soft white sugar or commercial foam nickel, wherein the mass ratio of white granulated sugar to soft white sugar in the mixture of white granulated sugar and soft white sugar is 0.5-1:0.5-1; the size of the commercial foam nickel is 30*30mm-70*70mm and the thickness is 5-10mm.

3. The preparation method according to claim 1, characterized in that, The ultrasonic mixing time in step 1 is 40-60min and the vacuum time is 30-40min; The heating and curing conditions in step 1 are as follows: When the sacrificial template is a mixture of white granulated sugar and soft white sugar, the heating and curing time is 40-60min and the heating and curing temperature is 90-100℃; When the sacrificial template is commercial foam nickel, the heating and curing time is 30-40min and the heating and curing temperature is 160-170℃.

4. The method of claim 1, wherein, The template remover in step 2 is water or a ferric chloride solution; When the template remover is a ferric chloride solution, the concentration is 0.8M-1.5M; The mass ratio of the template remover to the composite in step 2 is 30-40:8-15; The cleaning agent in step 2 is water or ethanol and the addition amount is 300-350% of the template remover; The pore size of the flexible porous PDMS substrate obtained in step 2 is 30um-500um.

5. The preparation method according to claim 1, characterized in that, The radio frequency conditions in step 3 are as follows: The radio frequency intensity is 90%-100%; The radio frequency time is 180-200s; The crosslinking agent in the solvent containing a crosslinking agent in step 3 is trichloro(1H,1H,2H,2H-tridecafluoro-n-octyl)silane or n-octyltrichlorosilane and the solvent is N,N-dimethylformamide, wherein the mass ratio of the solvent to the crosslinking agent is 7-7.5:1; The washing in step 3 is as follows: placing the flexible porous PDMS substrate after light-avoiding standing in water and ethanol for 1-5min, repeating 2-4 times.

6. The method of claim 1, wherein, The light-avoiding standing time in step 3 is 48-72h; The drying conditions in steps 2 and 3 are as follows: The drying temperature is 20-40℃; The drying time is 12-20h.

7. Use of a flexible porous membrane obtained by the process according to any one of claims 1 to 6 in the recognition of polar and non-polar gases, characterized in that, A conductive aluminum paper is pasted at the bottom of the flexible porous film, different polarity gases are pushed in to form different voltage intensities, and then the polar and non-polar gases are identified.

8. Use according to claim 7, characterized in that, The flexible porous membrane is a 13F-C-PDMS and foam nickel composite, a 13F-C-PDMS and mixed sugar composite, a 13H-C-PDMS and foam nickel composite, or a 13H-C-PDMS and mixed sugar composite. The pore size of the flexible porous membrane is 30um to 500um.

9. Use according to claim 7, characterized in that, The gas is selected from at least one of water vapor, nitrogen, ethanol gas, ammonia, and preferably nitrogen and water vapor. The voltage strength is formed by at least one of water vapor-sugar 13F, water vapor-nickel 13F, water vapor-sugar 13H, water vapor-nickel 13H, nitrogen-sugar 13F, nitrogen-nickel 13F, nitrogen-sugar 13H, and nitrogen-nickel 13H.

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