Interface joint reinforced composite membrane and preparation method and application thereof

Abstract

The application relates to the field of high-molecular composite membrane materials, in particular to an interface joint reinforced composite membrane and a preparation method and application thereof. The preparation method comprises the following steps: S1, carrying out gas phase hydration treatment on Silicalite-1 particles which are surface modified by a silane coupling agent in a predetermined temperature and humidity environment, to obtain modified Silicalite-1 particles carrying a water molecule induced layer; S2, adding the modified Silicalite-1 particles carrying the water molecule induced layer into a polydimethyl diethoxysilane (PDMDES) prepolymer solution, and carrying out ultrasonic treatment in a 0-10 DEG C environment, to obtain a composite membrane solution; and S3, coating the composite membrane solution on the surface of a base film through a blade coating process, and carrying out step-by-step solidification in an oven, to obtain the interface joint reinforced composite membrane. The prepared interface joint reinforced composite membrane has excellent pervaporation separation performance on the basis of maintaining good thermal stability and reducing non-selective leakage channels.

Description

Technical Field

[0001] This application relates to the field of polymer composite membrane materials, and in particular to a composite membrane with enhanced interfacial bonding, its preparation method, and its application. Background Technology

[0002] Alcohols (such as methanol, ethanol, and butanol) are a renewable new energy source with good environmental value and application prospects. Pervaporation membrane separation technology is often used for the separation and purification of alcohols due to its simple operation and relatively low energy consumption. Polydimethyldiethoxysilane (PDMDES) is one of the commonly used organic membrane materials.

[0003] However, in pervaporation separation applications, a single polymer selective layer is often limited by the trade-off between high permeation flux and high separation factor. To overcome this trade-off, existing technologies typically fill the polymer matrix with aluminum-free zeolite particles (such as Silicalite-1) with regular pore structures to prepare a hybrid matrix composite membrane. The introduction of porous particles can theoretically synergistically improve the separation performance, thermal stability, and mechanical strength of the composite membrane.

[0004] Nevertheless, in existing PDMDES / Silicalite-1 composite membrane preparation processes (such as directly curing at high temperatures after mixing silane coupling agent-modified particles with a prepolymer solution), the interfacial compatibility between inorganic particles and the organic polymer matrix often falls short of ideal standards. Due to the inherent differences in their physicochemical properties, coupled with the fact that conventional preparation processes often employ single-step high-temperature thermal curing, the rapid evaporation of solvents and the rapid crosslinking of the polymer matrix can lead to the accumulation of significant thermal and shrinkage stresses within the membrane. If the inorganic particle surface fails to form a sufficiently strong chemical bond with the organic matrix, the release of internal stress can easily cause the polymer molecular chains to peel off from the particle surface, thereby promoting the formation of microscopic physical gaps at the phase separation interface.

[0005] How to effectively improve the interfacial compatibility between inorganic particles and organic polymer matrix, reduce the generation of microstructural defects during mixing and curing, and thus prepare a composite membrane with both excellent structural density and pervaporation separation performance is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the aforementioned issues, this application aims to provide a composite membrane with enhanced interfacial bonding, its preparation method, and its applications. Through the design of the overall preparation process, a composite membrane exhibiting both excellent compactness and pervaporation separation performance was prepared.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows: A method for preparing a composite film with enhanced interfacial bonding includes: S1: Silicalite-1 (all-silica molecular sieve) particles with silane coupling agent surface modified are subjected to gas phase hydration treatment under a predetermined temperature and humidity environment to obtain modified Silicalite-1 particles carrying a water molecule induction layer. S2: Modified Silicalite-1 particles carrying a water molecule induction layer are added to a PDMDES prepolymerization solution and ultrasonically treated in an environment of 0~10 ℃ to obtain a composite membrane solution; S3: The composite membrane solution is coated onto the surface of the base membrane and then subjected to a step-by-step curing process in an oven to obtain a composite membrane with enhanced interfacial bonding; wherein, the step-by-step curing process includes a hydrolysis stage with sequentially increasing temperature, an interfacial pre-crosslinking stage, and a crosslinking curing stage.

[0008] Further, step S1 includes: S101: Dry Silicalite-1 particles are mixed with silane coupling agent and added to n-heptane. The mixture is stirred in a water bath and centrifuged and washed to obtain Silicalite-1 particles with silane coupling agent surface modification. S102: Silicalite-1 particles modified with silane coupling agent were dried in a vacuum environment at 50 °C; S103: The dried silane coupling agent surface-modified Silicalite-1 particles are transferred to a gas phase hydration reactor and left to stand for 2 to 4 hours under a humidity of 70% to 80% to obtain modified Silicalite-1 particles carrying a water molecule induction layer.

[0009] Furthermore, in step S1, the silane coupling agent is vinyltriethoxysilane (VTES).

[0010] Further, step S2 includes: S201: Provides a prepolymerization solution of polydimethyldiethoxysilane (PDMDES); S202: Add modified Silicalite-1 particles carrying a water molecule induction layer to the PDMDES prepolymerization solution to obtain a mixed solution; S203: The mixed solution is ultrasonically treated in an ice-water bath for 10-20 minutes to obtain a composite membrane solution.

[0011] Furthermore, in step S3, the stepped curing includes: Hydrolysis stage: constant temperature treatment at 30~40 ℃ for 2~4 h; Interface pre-crosslinking stage: Heat to 75~80 ℃ at a heating rate of 0.8~1.2 ℃ / min and hold for 2~3 h; Crosslinking and curing stage: Heat to 110-130 ℃ at a heating rate of 0.8-1.2 ℃ / min and hold for 10-14 hours.

[0012] Further, in step S1, the molar ratio of Silicalite-1 particles (calculated as silica (SiO2)) to silane coupling agent is 26:1 to 30:1.

[0013] Furthermore, the PDMDES prepolymer solution comprises: dimethyldiethoxysilane, vinyltriethoxysilane, dibutyltin dilaurate, and n-heptane.

[0014] This application also provides composite films with enhanced interfacial bonding prepared by the preparation method described above.

[0015] This application also provides the application of the interface-strengthened composite membrane as described above in the pervaporation separation of alcohol-based substances.

[0016] In summary, this application has the following beneficial effects: 1. This application constructs a microscopic water molecule-induced layer by vapor-phase hydration treatment of surface-modified Silicalite-1 particles. Combined with low-temperature solution preparation and a step-by-step curing process, a dense chemically bonded transition layer is successfully constructed between the inorganic particles and the organic polymer matrix, significantly improving the compatibility of the two-phase interface. This preparation method helps to smoothly release the thermal stress during film formation, reducing the generation of interfacial gaps, microcracks, and pores. The synergistic effect of these processes enables the prepared interfacially reinforced composite membrane to effectively reduce non-selective leakage channels while maintaining good thermal stability. This results in a significant improvement in separation selectivity during the pervaporation separation of alcohol-based substances while maintaining a high permeation flux level.

[0017] 2. In this application, modified Silicalite-1 particles carrying a water molecule induction layer are mixed with a PDMDES prepolymer solution and subjected to ultrasonic treatment under low-temperature conditions. This low-temperature solution preparation method can promote uniform dispersion of particles by utilizing ultrasonic shear force, while effectively inhibiting the premature gelation (premature crosslinking) of macromolecular prepolymers in the prepolymer solution under the induction of trace amounts of water and catalysts. This avoids irreversible chemical aggregation of particles, ensures the leveling and coatability of the composite membrane solution, and lays a rheological foundation for the subsequent formation of a continuous and complete thin film structure.

[0018] 3. This application employs a stepped curing process consisting of a hydrolysis stage, an interfacial pre-crosslinking stage, and a crosslinking curing stage, with sequentially increasing temperatures. This process guides the prepolymer and crosslinking agent in the system to preferentially undergo localized directional hydrolysis and dehydration condensation at the water molecule-induced layer on the surface of the modified particles, gradually constructing an interfacial transition layer that encapsulates the particles. Simultaneously, the gentle temperature gradient provides the system with sufficient time for venting and stress buffering, avoiding the rapid boiling and evaporation of solvents and interfacial moisture caused by single-step high-temperature curing, reducing the risk of physical structural damage within the polymer matrix, and improving the compactness of the composite separation membrane. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic flowchart of a method for preparing an interface-strengthened composite membrane according to this application. Figure 2 This is a pathway diagram of silicalite-1 modified with silane coupling agent in Example 1 of this application; Figure 3 This is a schematic diagram of the intermediate molecular structure after hydrolysis of the water molecule-induced layer in Example 1 of this application; Figure 4 This is a schematic diagram of the molecular structure of the composite membrane prepared in Example 1 of this application; Figure 5 This is a comparison of the Fourier transform infrared spectra of Silicalite-1 particles before and after modification in Example 1 of this application. Figure 6 This is a scanning electron microscope (SEM) image of the composite membrane prepared in Example 1 of this application; Figure 7 A schematic diagram of the pervaporation testing system provided in this application; Figure 8 This is a scanning electron microscope (SEM) image of the composite membrane prepared in Comparative Example 1 of this application; Figure 9 This is a scanning electron microscope (SEM) image of the composite membrane prepared in Comparative Example 3 of this application; Figure 10 Thermogravimetric analysis (TGA) curves of Example 1 and Comparative Example 1 provided for this application. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this application, the technical solutions of this application will be further described below in conjunction with the accompanying drawings and embodiments.

[0021] On the one hand, refer to Figure 1This application provides a composite film with enhanced interfacial bonding and a method for preparing the same, the preparation method comprising: S1: Silicalite-1 particles with surface modified by silane coupling agent are subjected to gas phase hydration treatment under a predetermined temperature and humidity environment to obtain modified Silicalite-1 particles carrying a water molecule induction layer. S2: Modified Silicalite-1 particles carrying a water molecule induction layer are added to a polydimethyldiethoxysilane (PDMDES) prepolymerization solution and ultrasonically treated in an environment of 0~10 ℃ to obtain a composite membrane solution; S3: The composite membrane solution is coated onto the surface of the base membrane and then subjected to a step-by-step curing process in an oven to obtain a composite membrane with enhanced interfacial bonding; wherein, the step-by-step curing process includes a hydrolysis stage with sequentially increasing temperature, an interfacial pre-crosslinking stage, and a crosslinking curing stage.

[0022] Furthermore, a specific preparation method is provided in Example 1.

[0023] Example 1 This embodiment provides the following optional preparation method: (1) VTES surface modification and vapor phase hydration treatment Weigh 2.5 g of pre-dried Silicalite-1 particles (to remove internally adsorbed moisture) and mix them with 0.3 g of vinyltriethoxysilane (VTES) in 10 g of n-heptane. Stir continuously for 10 h in a constant temperature water bath at 70 ℃, followed by multiple centrifugal washings. After washing, place the modified particles under vacuum and dry at 50 ℃ to remove residual n-heptane solvent. Then, transfer the dried particles to a closed gas-phase hydration reactor (using a saturated sodium chloride solution to maintain a constant relative humidity of approximately 75%) and allow them to stand in a powder dispersion state for 3 hours. This allows the surface of the modified Silicalite-1 particles to adsorb trace amounts of moisture through residual silanol groups, resulting in modified Silicalite-1 particles carrying a microscopic water molecule-induced layer. Figure 2 As shown.

[0024] (2) Preparation of PDMDES prepolymer solution Weigh 5 g of dimethyldiethoxysilane (DMDES) and add it to 10 g of n-heptane. Stir at room temperature for 1 h to disperse it evenly. Then add 3 g of VTES and 0.2 g of dibutyltin dilaurate to the mixture in sequence. Continue stirring at room temperature for 1 h to obtain a PDMDES prepolymer solution.

[0025] (3) Low-temperature preparation of composite membrane solution Weigh 0.62 g of the modified Silicalite-1 particles carrying the water molecule-induced layer obtained in step (1) above, and add them to the PDMDES prepolymerization solution in step (2). Place the resulting mixture in an ice-water bath and sonicate for 15 minutes. Under this low-temperature condition, the particles are dispersed uniformly by ultrasonic shearing force, while inhibiting the premature gelation of the macromolecular prepolymer in the prepolymerization solution in the presence of water molecules, thus obtaining a composite membrane solution with uniformly distributed modified Silicalite-1 particles.

[0026] (4) Step-curing film formation The composite membrane solution obtained in step (3) was poured onto the ethanol-wetted polyvinylidene fluoride (PVDF) base membrane and coated with a 90 μm doctor blade. Subsequently, it was transferred to a programmable temperature-controlled oven with micro-air circulation and subjected to the following stepped degassing and curing process: Stage 1 (Isothermal Exhaust and Interfacial Hydrolysis): The system was treated at a constant temperature of 35 °C for 3 hours. This allowed the heptane solvent to slowly evaporate, simultaneously inducing localized, directional hydrolysis of the prepolymer and crosslinking agent at the water molecule-inducing layer on the surface of the modified Silicalite-1 particles, generating silanol groups, such as... Figure 3 As shown.

[0027] The second stage (interfacial pre-crosslinking): The temperature is slowly increased to 80 °C at a rate of 1.0 °C / min and held for 2 hours. This allows the silanol groups enriched at the interface to preferentially undergo dehydration condensation reactions with the hydroxyl groups remaining on the particle surface and the crosslinking agent, forming a chemically bonded transition layer that encapsulates the particles.

[0028] The third stage (deep curing of the matrix): Continue heating at a rate of 1.0 ℃ / min to 120 ℃ and hold for 12 hours to complete the deep crosslinking and curing of the PDMDES main continuous phase; finally, a composite film with enhanced interfacial bonding (PDMDES / Silicalite-1) is obtained, such as... Figure 4 As shown.

[0029] It should be noted that, Figure 3 and Figure 4 middle: (The octagon in the image) represents Silicalite-1 particles; (The curved chain structure in the image) represents the long-chain molecular formula formed by the polymerization of dimethyldiethoxysilane (DMDES) and vinyltriethoxysilane (VTES), or... Figure 4 Molecular structures with similar structures; Y represents the molecular structure of the silane coupling agent that cannot be hydrolyzed.

[0030] Figure 5To characterize the Silicalite-1 particles before and after VTES modification using a Fourier transform infrared spectrometer (in this embodiment, a Nicolet iS50 device manufactured by Shaanxi Yingmei Electronics), the comparison results are as follows: Figure 5 As shown: Figure 5 The characteristic peaks of hydroxyl groups on the Silicalite-1 particle spectrum after modification were significantly reduced, while the characteristic peaks of groups on VTES were increased, proving that the surface modification was completed.

[0031] The cross-sectional morphology of the interface-strengthened composite film prepared in Example 1 was characterized using a field emission scanning electron microscope (a Hitachi SU8230 microscope was used in this embodiment, manufactured by Hitachi, Japan). The results are as follows: Figure 6 As shown, the modified Silicalite-1 particles exhibit a uniform dispersion in the PDMDES continuous phase matrix, with no obvious macroscopic agglomeration. The interfacial bonding between the particle phase and the polymer matrix phase is tight, demonstrating excellent compatibility. No obvious phase separation interface gaps were observed, nor were any microscopic cracks or pore defects caused by the rapid evaporation of n-heptane solvent or rapid polymer crosslinking. Therefore, the low-temperature solution preparation and step-by-step curing process with a microscopic water molecule induction layer used in this embodiment not only successfully constructs a dense chemically bonded transition layer between the inorganic particles and the organic matrix, but also fully releases the thermal stress during film formation, thereby endowing the composite film with excellent structural integrity and interfacial density.

[0032] The pervaporation performance of the interface-strengthened composite membrane prepared in Example 1 was tested. Pervaporation test conditions: the test material was an ethanol / water solution containing 5 wt% ethanol, and the test temperature was 40 °C.

[0033] The tests were conducted using a self-made pervaporation performance testing system, which is as follows: Figure 7 As shown in the diagram. Specifically, the testing system mainly consists of a water bath heater, a peristaltic pump, a membrane reactor, a buffer chamber, a vacuum gauge, a liquid nitrogen cold trap, a drying tube, and a vacuum pump pipeline. During the test operation, the test solution is placed in the water bath heater for constant temperature and continuous stirring. The peristaltic pump drives the solution to circulate through the feed side of the membrane reactor, and the unpermeated retentate flows directly back to the water bath heater. The permeate side of the membrane reactor is connected to the vacuum pipeline. Under the negative pressure provided by the vacuum pump, the gaseous components that permeate through the composite membrane are condensed and collected in the liquid nitrogen cold trap after passing through the buffer chamber, facilitating subsequent mass and component analysis. Simultaneously, the system monitors the vacuum level on the permeate side in real time using a vacuum gauge, and a drying tube is installed before the vacuum pump to prevent uncondensed exhaust gas moisture from damaging the vacuum equipment.

[0034] The composite membrane with enhanced interfacial bonding prepared in Example 1 had a pervaporation performance test result of 4918.6 g. m -2 h -1 The separation factor was 12.72.

[0035] Furthermore, to compare and verify the pervaporation performance of the composite membrane obtained by the preparation method of Example 1, the following comparative example is provided: Comparative Example 1 This comparative example provides a method for preparing a PDMDES / Silicalite-1 composite membrane, specifically including the following steps: (1) The dried Silicalite-1 particles were mixed with vinyltriethoxysilane (VTES) and added to n-heptane. The mixture was stirred in a water bath at 70 °C for 10 h, centrifuged and washed, and then dried in a vacuum environment at 70 °C for 7 h to obtain surface-modified Silicalite-1 particles (without gas phase hydration treatment). (2) A PDMDES prepolymer solution was prepared using the same method as in Example 1; (3) The surface-modified Silicalite-1 particles were added to the PDMDES prepolymer solution and ultrasonically treated at 70 °C for 15 minutes to obtain the composite film solution. (4) The composite membrane solution was coated onto the PVDF base membrane wetted with ethanol and directly transferred to an oven at 120 °C for heating and curing for 24 h to obtain the PDMDES / Silicalite-1 composite membrane.

[0036] The specifications and quantities of the raw materials used in the above steps are the same as in Example 1.

[0037] Characterization and test results: Refer to Figure 8 The cross-sectional morphology characterization (SEM) results showed that although the selective layer of the composite membrane prepared in Comparative Example 1 contained particle filling, the compatibility between the inorganic particles and the organic polymer matrix was weak, and visible microscopic physical gaps still existed at the phase interface. Using the same pervaporation test conditions as Example 1, the permeation flux of the composite membrane in Example 1 was 5686.2 g. m -2 h -1 The separation factor is 8.56.

[0038] Comparative Example 2 The only difference between the preparation method of this comparative example and Example 1 is the preparation temperature of the composite membrane solution: In step (3), the modified Silicalite-1 particles carrying the water molecule induction layer obtained in step (1) were weighed and added to the PDMDES prepolymer solution. Instead of preparing the solution at low temperature, the particles were ultrasonically treated at 70 °C for 15 minutes. The remaining preparation steps were consistent with those in Example 1.

[0039] Results: During the preparation process, premature cross-linking occurred under the combined action of microscopic water molecules and the catalyst at 70 °C, leading to irreversible chemical aggregation of the particles. The rheological properties of the mixture changed significantly, with increased viscosity and premature gelation. This gel-like mixture lost its basic leveling and coatability, making it impossible to coat a PVDF substrate to form a continuous and complete film structure; therefore, the composite membrane could not be successfully prepared.

[0040] Comparative Example 3 The preparation method provided in this comparative example differs from that in Example 1 only in the film-forming and curing process: In step (4), after the composite membrane solution was coated onto the PVDF base membrane, the step-by-step degassing and curing process was not performed. Instead, it was directly transferred to an oven at 120 °C for single-step heating and curing. The remaining preparation steps were consistent with those in Example 1.

[0041] Characterization and test results: Refer to Figure 9 The cross-sectional morphology characterization results showed that the composite membrane exhibited a sponge-like porous structure with large pores and permeable channels inside. Simultaneously, the inorganic particles showed significant agglomeration, failing to form a continuous, dense polymer phase structure. Furthermore, the high temperature caused rapid evaporation of surface moisture from the particles, preventing effective interfacial coupling reactions. During pervaporation testing, the aforementioned physical structural damage caused the composite membrane to completely lose its density selectivity, resulting in direct leakage of the feed liquid through the large pores and channels, thus losing its separation selectivity.

[0042] Furthermore, the thermal stability of Example 1 and Comparative Example 1 was characterized using a simultaneous thermogravimetric analyzer (the equipment used in the embodiments and comparative examples provided in this application is a METTLER TOLEDO TGA / DSC3+, manufactured by Mettler China). The test conditions were 10 °C under a nitrogen atmosphere. min -1 The heating rate was increased from 40 °C to 800 °C, and thermal decomposition curves of the two films were obtained, as shown below. Figure 10 As shown.

[0043] from Figure 10It can be seen that the composite membranes prepared in Example 1 and Comparative Example 1 exhibit similar macroscopic thermal degradation trends. Both show extremely low weight loss rates in the range of approximately 300 °C, indicating excellent thermal stability at typical pervaporation operating temperatures. In the main thermal decomposition range of approximately 350 °C to 450 °C, the weight loss curve of Example 1 shows a very slight shift towards the lower temperature side compared to Comparative Example 1, and its final residual mass at 800 °C is slightly lower than that of Comparative Example 1. This objective thermodynamic microscopic difference indicates that the vapor-phase hydration and step-by-step curing process used in Example 1, while optimizing the inorganic / organic interface compatibility and eliminating microscopic pore defects, alters the local crosslinking network distribution or interfacial chemical bonding state of the polymer matrix; however, from a macroscopic perspective, it does not damage the main heat-resistant framework of the composite membrane. In summary, Example 1 significantly improves the selective separation performance of pervaporation while maintaining a high level of thermal stability comparable to conventional processes (Comparative Example 1), fully meeting the heat-resistant application requirements in actual alcohol-water mixture separation processes.

[0044] On the other hand, based on the performance of the interface-strengthened composite membrane prepared by the preparation method of this application, this application also provides the application of the interface-strengthened composite membrane in the pervaporation separation of alcohol-based substances. Specifically, the interface-strengthened composite membrane can be applied to the pervaporation separation and purification process of alcohol / water mixed solutions (such as ethanol / water, methanol / water systems).

[0045] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a composite film with enhanced interfacial bonding, characterized in that, include: S1: Silicalite-1 particles with surface modified by silane coupling agent are subjected to gas phase hydration treatment under a predetermined temperature and humidity environment to obtain modified Silicalite-1 particles carrying a water molecule induction layer. S2: Modified Silicalite-1 particles carrying a water molecule induction layer are added to a PDMDES prepolymerization solution and ultrasonically treated at 0~10℃ to obtain a composite membrane solution. S3: The composite membrane solution is coated onto the surface of the base membrane and then subjected to a step-by-step curing process in an oven to obtain a composite membrane with enhanced interfacial bonding; wherein, the step-by-step curing process includes a hydrolysis stage with sequentially increasing temperature, an interfacial pre-crosslinking stage, and a crosslinking curing stage.

2. The preparation method according to claim 1, characterized in that, Step S1 includes: S101: Dry Silicalite-1 particles are mixed with silane coupling agent and added to n-heptane. The mixture is stirred in a water bath and centrifuged and washed to obtain Silicalite-1 particles with silane coupling agent surface modification. S102: Silicalite-1 particles modified with silane coupling agent were dried in a vacuum environment at 50 °C; S103: The dried silane coupling agent surface-modified Silicalite-1 particles are transferred to a gas phase hydration reactor and left to stand for 2 to 4 hours under a humidity of 70% to 80% to obtain modified Silicalite-1 particles carrying a water molecule induction layer.

3. The preparation method according to claim 2, characterized in that, In step S1, the silane coupling agent is vinyltriethoxysilane.

4. The preparation method according to claim 1, characterized in that, Step S2 includes: S201: Provides PDMDES prepolymerization solution; S202: Add modified Silicalite-1 particles carrying a water molecule induction layer to the PDMDES prepolymerization solution to obtain a mixed solution; S203: The mixed solution is ultrasonically treated in an ice-water bath for 10-20 minutes to obtain a composite membrane solution.

5. The preparation method according to claim 1, characterized in that, In step S3, the stepped curing includes: Hydrolysis stage: constant temperature treatment at 30~40 ℃ for 2~4 h; Interface pre-crosslinking stage: Heat to 75~80 ℃ at a heating rate of 0.8~1.2 ℃ / min and hold for 2~3 h; Crosslinking and curing stage: Heat to 110-130 ℃ at a heating rate of 0.8-1.2 ℃ / min and hold for 10-14 h.

6. The preparation method according to claim 1, characterized in that, The molar ratio of Silicalite-1 particles to silane coupling agent is 26:1 to 30:

1.

7. The preparation method according to claim 1, characterized in that, The PDMDES prepolymer solution includes: dimethyldiethoxysilane, vinyltriethoxysilane, dibutyltin dilaurate, and n-heptane.

8. The composite membrane with enhanced interfacial bonding prepared by the preparation method according to any one of claims 1-7.

9. The application of the interface-strengthened composite membrane as described in claim 8 in the pervaporation separation of alcohol-based substances.

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