A gas phase crosslinking organic solvent resistant uniform pore membrane and a preparation method thereof

Abstract

The application discloses a gas-phase crosslinking organic solvent-resistant uniform pore membrane and a preparation method thereof. The preparation method comprises the following steps: placing a block copolymer uniform pore membrane containing a benzene ring in a mixed vapor to perform gas-phase crosslinking, so as to obtain a gas-phase crosslinking organic solvent-resistant uniform pore membrane; the mixed vapor comprises a gaseous methoxy-containing alkane and a gaseous acidic substance; the gaseous acidic substance comprises one or more of an acid in a gaseous state at normal temperature and pressure, a heated acid or a reduced-pressure acid. Through the gas-phase crosslinking technology, the crosslinking of the benzene ring-containing chain segment is completed in an environment without competition between a dissolution process and a crosslinking process, the preparation of the organic solvent-resistant uniform pore membrane is realized, meanwhile, the structure of the uniform pore layer and the support layer of the membrane is ensured not to collapse, and the pure water flux of the prepared gas-phase crosslinking organic solvent-resistant uniform pore membrane is 450 L / (m 2 ·h·bar), and the permeation performance is far superior to that of a liquid-phase crosslinking uniform pore membrane.

Description

Technical Field

[0001] This application relates to the field of high-performance separation membrane materials technology, and in particular to a gas-phase crosslinked organic solvent-resistant uniformly porous membrane and its preparation method. Background Technology

[0002] The petrochemical and pharmaceutical industries commonly involve separation and purification in organic solvent environments. Compared to traditional separation techniques (such as distillation, evaporation, crystallization, extraction, and column chromatography), membrane separation technology offers advantages such as cost-effectiveness, environmental friendliness, continuous operation, robust process design, and smaller plant footprint, meeting the energy and economic sustainability requirements of separation and purification processes. Currently, commercially available organic solvent-resistant membranes are mainly polymer membrane materials, which suffer from inherent problems such as disordered separation channels and wide pore size distribution, leading to a bottleneck of mutual constraint between permeability and selectivity, failing to meet the demands for efficient and high-precision separation in chemical and pharmaceutical synthesis. Developing organic solvent-resistant homogeneous porous membrane materials with uniform channels, regular structures, and high pore density has become a research hotspot in environmental, materials, and chemical engineering fields.

[0003] Uniformly porous membranes prepared by a combination of block copolymer self-assembly and solvent-inducible phase separation, namely block copolymer uniformly porous membranes, possess uniform channels with close packing of hexagonal / quadrilateral pores and a pore density close to the theoretical limit (>10). 14 m -2 With its unique structure, including an ultrathin separation layer (<200nm), block copolymer membranes can simultaneously achieve high permeability and selectivity, making them one of the most ideal materials for overcoming the bottlenecks in membrane separation technology. However, most block copolymer uniformly porous membranes are currently soluble in most organic solvents, making them unsuitable for separation and purification in complex organic solvent environments. The few organic solvent-resistant block copolymer uniformly porous membranes employ liquid-phase crosslinking methods, placing the membrane in a high-concentration reaction solution for crosslinking, such as a high-concentration FeCl3 and dimethoxymethane (FDA) system. Because the reaction solution components dissolve the block copolymer, the dissolution rate is often higher than the crosslinking rate, leading to the destruction of the membrane's uniform porous structure and macroporous support layer, causing collapse and ultimately resulting in a significant decrease in membrane permeability, failing to meet the requirements of high-performance separation. Therefore, developing a method for preparing a solvent-resistant uniformly porous membrane that does not damage the membrane structure and meets the requirements of high permeability is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, this application provides a method for preparing a vapor-phase crosslinked organic solvent-resistant uniformly porous membrane. This method involves treating a block copolymer uniformly porous membrane containing benzene rings in a vapor environment of a reaction solution. Vapor-phase catalyst and crosslinking agent molecules undergo a crosslinking reaction with the benzene rings in the uniformly porous membrane to obtain an organic solvent-resistant uniformly porous membrane. The vapor-phase crosslinked organic solvent-resistant uniformly porous membrane maintains a complete uniform porous structure and a macroporous structure in the support layer, exhibiting good organic solvent resistance and excellent permeability.

[0005] This application provides a method for preparing a vapor-phase crosslinked organic solvent-resistant uniformly porous membrane, comprising:

[0006] A block copolymer membrane containing benzene rings was placed in a mixed vapor to undergo gas-phase crosslinking, resulting in a gas-phase crosslinked organic solvent-resistant uniformly porous membrane.

[0007] The mixed vapor includes gaseous alkanes containing methoxy groups and gaseous acidic substances;

[0008] The gaseous acidic substances include one or more of the following: acids that are gases at room temperature and pressure, acids that are heated and vaporized, or acids that are vaporized under reduced pressure.

[0009] The gaseous methoxy-containing alkanes include one or more of the following: straight-chain alkane derivatives containing two or more methoxy groups (-OCH3), branched-chain alkane derivatives containing two or more methoxy groups (-OCH3), or cycloalkane derivatives containing two or more methoxy groups (-OCH3).

[0010] This application uses a block copolymer uniformly porous membrane containing benzene rings, methoxylated alkanes, and acidic substances as reaction raw materials. In some specific implementations, the block copolymer uniformly porous membrane containing benzene rings includes, but is not limited to, polystyrene-block-poly(4-vinylpyridine) (PS- b -P4VP), polystyrene-block-poly(2-vinylpyridine) (PS- b -P2VP), poly(tert-butylstyrene)-block-poly(4-vinylpyridine) (PtBS- b -P4VP), poly(4-trimethylsilylstyrene)-block-poly(4-vinylpyridine) (PtTMS- b -P4VP), poly(4-methylstyrene)-block-poly(4-vinylpyridine) (P4MS- b -P4VP), polystyrene-block-poly(ethylene oxide) (PS- b -PEO), polystyrene-block-poly(2-hydroxyethyl methacrylate) (PS- b -PHEMA), polystyrene-block poly(glyceryl methacrylate) (PS- b-PGMA), polystyrene-block-poly(N-isopropylacrylamide) (PS- b -PNIPAM), polystyrene-block-poly(acrylic acid) (PS- b -PAA), polyisoprene-block-polystyrene-block-poly(4-vinylpyridine) (PI- b -PS- b -P4VP), polyisoprene-block-polystyrene-block-poly(N,N-dimethylacrylamide) (PI- b -PS- b -PDMA), polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (PS- b -P2VP- b -PEO), poly(styrene)-block-poly(4-vinylpyridine)-block-poly(propylene sulfuride) (PS- b -P4VP- b -PPS), poly(4-(2-hydroxyethylthio)-2-methylbutene-copolymer-4-(2-hydroxyethylthio)-3-methylbutene-copolymer-isoprene)-block-polystyrene-block-poly(4-vinylpyridine) (P(HTMB- r -I)- b -PS- b -P4VP), polystyrene-block poly(hydroxyethyl methacrylate-2-succinoxyethyl methacrylate) (PS- b -P(HEMA- r -SEMA) or polystyrene-block-poly(hydroxyethyl methacrylate-co-hydroxyethyl methacrylate-glycine) block copolymer PS- b -P(HEMA- r This application does not have any special requirements for the selection of block copolymer uniformly porous membranes containing benzene rings (one or more of HEMA-Gly-NH2).

[0011] In some specific implementations, the method for preparing the mixed vapor includes: mixing and vaporizing a methoxylated alkane and an acidic substance to obtain a mixed vapor; the vaporization method includes any one of ambient temperature and pressure vaporization, heating vaporization, depressurization vaporization, or heating and depressurization vaporization. The acidic substance includes acids that are gases at ambient temperature and pressure (e.g., hydrogen halides, sulfide hydrides, other non-metallic hydrides), and can be vaporized by heating or depressurization, or by using both heating and depressurization simultaneously with vaporizable acids (e.g., nitric acid, small molecule organic acids, etc.). In some specific implementations, the gaseous acidic substance includes, but is not limited to, one or more of hydrogen chloride, hydrogen sulfide, hydrogen cyanide, nitric acid, formic acid, acetic acid, propionic acid, butyric acid, trifluoromethanesulfonic acid, fluorosulfonic acid, or methanesulfonic acid. This application does not have specific requirements for the selection of the acidic substance.

[0012] The methoxy-containing alkanes include, but are not limited to, straight-chain alkane derivatives containing two or more methoxy groups (-OCH3) such as dimethoxymethane, 1,2-dimethoxyethane, 1,4-dimethoxybutane, 1,1,2-trimethoxyethane, and 2,2,3-trimethoxybutane, branched-chain alkane derivatives containing two or more methoxy groups (-OCH3) such as 1,3-dimethoxyneopentane, or cycloalkane derivatives containing two or more methoxy groups (-OCH3) such as 1,3-dimethoxycyclohexane. This application does not have any special requirements for the selection of methoxy-containing alkanes. In some specific implementations, the gaseous methoxy-containing alkanes include, but are not limited to, one or more of dimethoxymethane, 1,1-dimethoxyethane, 1,2-dimethoxyethane, 1,1,2-trimethoxyethane, 2,2-dimethoxypropane, 1,3-dimethoxypropane, 2,2-dimethoxybutane, 2,2,3-trimethoxybutane, 1,4-dimethoxybutane, 1,3-dimethoxycyclohexane, or 2,2-dimethoxypentane. This application does not have any special requirements for the selection of gaseous methoxy-containing alkanes.

[0013] In some specific implementations, the volume ratio of the methoxylated alkane to the acidic substance is (0.1-1.2):(3-9), which can be 0.1:9, 0.1:8, 0.1:7, 0.1:6, 0.1:5, 0.1:4, 0.1:3, 0.1:2, 0.2:9, 0.2:8, 0.2:7, 0.2:6, 0.2:5, 0.2:4, 0.2:3, 0.3:9, 0.3:8, 0.3:7, 0.3:6, 0.3:5, 0.3:4, 0.3:3, 0.5:3, 0.8:3, 1:3, 1:5, 1:6, 1:7, or 1:9, preferably (0.3-0.8):(3-6). In some specific implementations, the mass ratio of the methoxyl-containing alkane to the block copolymer membrane containing PS segments is 1:10 to 60:1, preferably 10:1 to 30:1.

[0014] In some specific implementations, the temperature of the gas-phase crosslinking is from 20°C to 100°C, and can be 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C, preferably 20-40°C; the time of the gas-phase crosslinking is from 0.1h to 96h, and can be 0.5h, 0.8h, 10h, 20h, 30h, 40h, 50h, 55h, or 60h, preferably 20-30h.

[0015] In some specific implementations, the concentration of the sodium hydroxide solution is from 0.1 mol / L to 10 mol / L, and can be 0.1 mol / L, 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L, 2 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, or 10 mol / L, preferably 4-8 mol / L. In some specific implementations, the washing time with sodium hydroxide solution is from 1 hour to 120 hours, which can be 1 hour, 10 hours, 20 hours, 30 hours, 40 hours, 50 hours, 60 hours, 70 hours, 80 hours, 90 hours, 100 hours, 110 hours, or 120 hours, preferably 30-60 hours; the washing time with water is from 1 hour to 120 hours, which can be 1 hour, 10 hours, 20 hours, 30 hours, 40 hours, 50 hours, 60 hours, 70 hours, 80 hours, 90 hours, 100 hours, 110 hours, or 120 hours, preferably 30-60 hours.

[0016] This application utilizes a gas-phase acidic substance to catalyze a gas-phase crosslinking reaction between gas-phase methoxylated alkanes and benzene rings in a block copolymer membrane containing benzene rings. This avoids the use of high-concentration reactant solutions and the destruction of the membrane structure, resulting in a complete gas-phase crosslinked membrane with intact pore structure and support layer structure.

[0017] The gas-phase crosslinked organic solvent-resistant homogeneous porous membrane prepared in this application maintains its structural integrity after being treated for 24 hours in various common organic solvents, including methanol, toluene, acetone, n-hexane, dimethylformamide, dimethylacetamide, chloroform, tetrahydrofuran, dimethyl sulfoxide, and N-methylpyrrolidone. It exhibits excellent solvent resistance and provides conditions for efficient and high-precision separation in organic solvent environments.

[0018] The gas-phase crosslinked organic solvent-resistant uniformly porous membrane prepared in this application exhibits excellent permeability, with a pure water flux of 450 L / (m²). 2 ·h·bar), ethanol flux is 220L / (m 2 ·h·bar), DMF flux is 200L / (m 2 (·h·bar), significantly superior to membrane systems prepared by liquid-phase crosslinking;

[0019] The preparation method described in this application crosslinks the most promising block copolymer membrane containing benzene rings, providing a key separation membrane material for efficient and high-precision separation in organic solvent environments.

[0020] The preparation method described in this application employs mild gas-phase reaction conditions, is simple to operate, and has a wide range of applications, providing a possibility for the scale-up preparation of organic solvent-resistant homogeneous porous membranes. Attached Figure Description

[0021] Figure 1 This is a SEM image of the vapor-phase crosslinked organic solvent-resistant uniformly porous membrane provided in Example 1 of this application;

[0022] Figure 2 This is a SEM image of the vapor-crosslinked organic solvent-resistant uniformly porous membrane provided in Example 1 of this application after immersion in DMF for 24 hours;

[0023] Figure 3 The infrared spectrum of the gas-phase crosslinked organic solvent-resistant uniformly porous membrane provided in Example 1 of this application;

[0024] Figure 4 The infrared spectrum of the gas-phase crosslinked organic solvent-resistant uniformly porous membrane provided in Example 2 of this application;

[0025] Figure 5 The vapor-phase crosslinked organic solvent-resistant uniformly porous membrane and PS- provided in Example 1 of this application b Flux diagram of the P4VP membrane;

[0026] Figure 6 SEM image of the liquid-phase crosslinked uniformly porous membrane provided in Comparative Example 1 of this application;

[0027] Figure 7SEM image of the uniformly porous membrane provided in Comparative Example 2 of this application;

[0028] Figure 8 This is a SEM image of the uniformly porous membrane provided in Comparative Example 2 of this application after immersion in DMF for 24 hours;

[0029] Figure 9 The flux diagram is for the liquid-phase crosslinked uniformly porous membrane provided in Comparative Example 1 of this application. Detailed Implementation

[0030] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0031] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0032] It should be understood that the order of steps or the sequence of actions is not important as long as this application remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0033] The use of any and all instances or exemplary language such as “e.g.” or “including” herein is merely intended to better illustrate the application and does not constitute a limitation on the scope of the application unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of this application.

[0034] Furthermore, the numerical ranges and parameters used to define this application are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any numerical value inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise explicitly stated, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately." Here, "approximately" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range.

[0035] The present application is further illustrated below with reference to embodiments. The scope of protection of the present application is not limited to the following embodiments.

[0036] Example 1

[0037] This embodiment provides a vapor-phase crosslinked organic solvent-resistant uniformly porous membrane, the preparation method of which includes:

[0038] The pre-prepared polystyrene-block-poly(4-vinylpyridine) (PS-) was used. b The P4VP homogeneous membrane was placed in a round-bottom flask. 1 mL of 1,4-dimethoxybutane and 10 mL of acetic acid were added to the Schlenk reaction flask. The round-bottom flask and the Schlenk reaction flask were connected by a distillation elbow. The reaction apparatus was then subjected to reduced pressure. After the vacuum gauge reading stabilized, the pressure was stopped. The reaction apparatus was sealed tightly and placed in an oven at 40°C for 20 h.

[0039] The reacted membrane was washed in a 4 mol / L NaOH solution of water and ethanol (water to ethanol volume ratio of 1:1) for 20 h to remove residual catalyst and crosslinking agent; then it was washed with pure water for 20 h to remove residual sodium hydroxide, finally obtaining a gas-phase crosslinked organic solvent resistant uniform porous membrane.

[0040] SEM tests were performed on the vapor-crosslinked organic solvent-resistant uniformly porous membrane provided in this embodiment, such as... Figure 1 As shown; the vapor-crosslinked organic solvent-resistant uniformly porous membrane provided in this embodiment was immersed in N,N-dimethylformamide (DMF) for 24 hours and tested. The SEM images of the test are shown below. Figure 2 As shown; the infrared spectrum of the vapor-phase crosslinked organic solvent-resistant uniformly porous membrane provided in this embodiment is as follows. Figure 3 As shown; solvent flux testing was performed on the gas-phase crosslinked organic solvent-resistant uniformly porous membrane provided in this embodiment. The test method was dead-end filtration, and the operating pressure was 1 bar. The tested gas-phase crosslinked organic solvent-resistant uniformly porous membrane and PS- b The flux diagram of the -P4VP membrane is shown below. Figure 5 As shown.

[0041] Example 2

[0042] This embodiment provides a vapor-phase crosslinked organic solvent-resistant uniformly porous membrane, the preparation method of which includes:

[0043] The pre-prepared polystyrene-block-poly(hydroxyethyl methacrylate) (PS-) was used. b The PHEMA homogeneous membrane was placed in a round-bottom flask. 1 mL of 1,4-dimethoxybutane and 10 mL of acetic acid were added to the Schlenk reaction flask. The round-bottom flask and the Schlenk reaction flask were connected by a distillation elbow. The reaction apparatus was then subjected to reduced pressure. After the vacuum gauge reading stabilized, the pressure was stopped. The reaction apparatus was sealed tightly and placed in an oven at 40°C for 20 h.

[0044] The reacted membrane was washed in a 4 mol / L NaOH solution of water and ethanol (water to ethanol volume ratio of 1:1) for 20 h to remove residual catalyst and crosslinking agent; then it was washed with pure water for 20 h to remove residual sodium hydroxide, finally obtaining a gas-phase crosslinked organic solvent resistant uniform porous membrane.

[0045] The infrared spectrum of the vapor-phase crosslinked organic solvent-resistant uniformly porous membrane provided in this embodiment is as follows: Figure 4 As shown.

[0046] Example 3

[0047] This embodiment provides a vapor-phase crosslinked organic solvent-resistant uniformly porous membrane, the preparation method of which includes:

[0048] The pre-prepared polystyrene-block-poly(4-vinylpyridine) (PS-) was used. b The P4VP homogeneous membrane was placed in a round-bottom flask. 1 mL of 1,4-dimethoxybutane and 10 mL of butyric acid were added to the Schlenk reaction flask. The round-bottom flask and the Schlenk reaction flask were connected by a distillation elbow. The reaction apparatus was then subjected to reduced pressure. After the vacuum gauge reading stabilized, the pressure was stopped. The reaction apparatus was sealed tightly and placed in an oven at 40°C for 20 h.

[0049] The reacted membrane was washed in a 4 mol / L NaOH solution of water and ethanol (water to ethanol volume ratio of 1:1) for 20 h to remove residual catalyst and crosslinking agent; then it was washed with pure water for 20 h to remove residual sodium hydroxide, finally obtaining a gas-phase crosslinked organic solvent resistant uniform porous membrane.

[0050] Example 4

[0051] This embodiment provides a vapor-phase crosslinked organic solvent-resistant uniformly porous membrane, the preparation method of which includes:

[0052] The pre-prepared polystyrene-block-poly(4-vinylpyridine) (PS-) was used. b The P4VP homogeneous membrane was placed in a round-bottom flask. 1.5 mL of 1,1,2-trimethoxyethane and 6 mL of trifluoromethanesulfonic acid were added to the Schlenk reaction flask. The round-bottom flask and the Schlenk reaction flask were connected by a distillation elbow. The reaction apparatus was then subjected to reduced pressure. After the vacuum gauge reading stabilized, the pressure was stopped. The reaction apparatus was sealed tightly and placed in an oven at 80°C for 6 hours.

[0053] The reacted membrane was washed in a 4 mol / L NaOH solution of water and ethanol (water to ethanol volume ratio of 1:1) for 20 h to remove residual catalyst and crosslinking agent; then it was washed with pure water for 20 h to remove residual sodium hydroxide, finally obtaining a gas-phase crosslinked organic solvent resistant uniform porous membrane.

[0054] Example 5

[0055] This embodiment provides a vapor-phase crosslinked organic solvent-resistant uniformly porous membrane, the preparation method of which includes:

[0056] The pre-prepared polystyrene-block-poly(4-vinylpyridine) (PS-) was used. b The P4VP homogeneous membrane was placed in a round-bottom flask. 1.5 mL of 1,1,2-trimethoxyethane and 6 mL of acetic acid were added to the Schlenk reaction flask. The round-bottom flask and the Schlenk reaction flask were connected by a distillation elbow. The reaction apparatus was then subjected to reduced pressure. After the vacuum gauge reading stabilized, the pressure was stopped. The reaction apparatus was sealed tightly and placed in an oven at 60°C for 6 hours.

[0057] The reacted membrane was washed in a 4 mol / L NaOH solution of water and ethanol (water to ethanol volume ratio of 1:1) for 1 h to remove residual catalyst and crosslinking agent; then it was washed with pure water for 1 h to remove residual sodium hydroxide, finally obtaining a gas-phase crosslinked organic solvent resistant uniform porous membrane.

[0058] Example 6

[0059] This embodiment provides a vapor-phase crosslinked organic solvent-resistant uniformly porous membrane, the preparation method of which includes:

[0060] The pre-prepared polystyrene-block-poly(4-vinylpyridine) (PS-) was used. b The -P4VP) homogeneous membrane was placed in a round-bottom flask. 1.5 mL of 1,1,2-trimethoxyethane and 8 mL of acetic acid were added to the Schlenk reaction flask. The round-bottom flask and the Schlenk reaction flask were connected by a distillation elbow. The reaction apparatus was then subjected to reduced pressure. After the vacuum gauge reading stabilized, the pressure was stopped. The reaction apparatus was sealed tightly and placed in an oven at 90°C for 4 hours.

[0061] The reacted membrane was washed in a 1 mol / L NaOH solution of water and ethanol (water to ethanol volume ratio of 1:1) for 1 h to remove residual catalyst and crosslinking agent; then it was washed with pure water for 1 h to remove residual sodium hydroxide, finally obtaining a gas-phase crosslinked organic solvent resistant uniform porous membrane.

[0062] Example 7

[0063] This embodiment provides a vapor-phase crosslinked organic solvent-resistant uniformly porous membrane, the preparation method of which includes:

[0064] The pre-prepared polystyrene-block-poly(2-vinylpyridine) (PS-) was used. b The -P2VP) homogeneous membrane was placed in a round-bottom flask. 1.5 mL of dimethoxymethane and 8 mL of acetic acid were added to the Schlenk reaction flask. The round-bottom flask and the Schlenk reaction flask were connected by a distillation elbow. The reaction apparatus was then depressurized. After the vacuum gauge reading stabilized, the depressurization was stopped. The reaction apparatus was sealed tightly and placed in an oven at 90°C for 4 hours.

[0065] The reacted membrane was washed in a 1 mol / L NaOH solution of water and ethanol (water to ethanol volume ratio of 1:1) for 1 h to remove residual catalyst and crosslinking agent; then it was washed with pure water for 1 h to remove residual sodium hydroxide, finally obtaining a gas-phase crosslinked organic solvent resistant uniform porous membrane.

[0066] Example 8

[0067] This embodiment provides a vapor-phase crosslinked organic solvent-resistant uniformly porous membrane, the preparation method of which includes:

[0068] The pre-prepared polystyrene-block-poly(hydroxyethyl methacrylate) (PS-) was used. b The PHEMA homogeneous membrane was placed in a round-bottom flask. 1 mL of 1,4-dimethoxybutane and 10 mL of butyric acid were added to the Schlenk reaction flask. The round-bottom flask and the Schlenk reaction flask were connected by a distillation elbow. The reaction apparatus was then subjected to reduced pressure. After the vacuum gauge reading stabilized, the pressure was stopped. The reaction apparatus was sealed tightly and placed in an oven at 40°C for 20 hours.

[0069] The reacted membrane was washed in a 4 mol / L NaOH solution of water and ethanol (water to ethanol volume ratio of 1:1) for 20 h to remove residual catalyst and crosslinking agent; then it was washed with pure water for 20 h to remove residual sodium hydroxide, finally obtaining a gas-phase crosslinked organic solvent resistant uniform porous membrane.

[0070] Example 9

[0071] This embodiment provides a vapor-phase crosslinked organic solvent-resistant uniformly porous membrane, the preparation method of which includes:

[0072] The pre-prepared polystyrene-block-poly(2-vinylpyridine) (PS-) was used. bThe P2VP homogeneous membrane was placed in a round-bottom flask. 1.5 mL of 1,1,2-trimethoxyethane and 6 mL of trifluoromethanesulfonic acid were added to the Schlenk reaction flask. The round-bottom flask and the Schlenk reaction flask were connected by a distillation elbow. The reaction apparatus was then subjected to reduced pressure. After the vacuum gauge reading stabilized, the pressure was stopped. The reaction apparatus was sealed tightly and placed in an oven at 80°C for 6 hours.

[0073] The reacted membrane was washed in a 4 mol / L NaOH solution of water and ethanol (water to ethanol volume ratio of 1:1) for 20 h to remove residual catalyst and crosslinking agent; then it was washed with pure water for 20 h to remove residual sodium hydroxide, finally obtaining a gas-phase crosslinked organic solvent resistant uniform porous membrane.

[0074] Example 10

[0075] This embodiment provides a vapor-phase crosslinked organic solvent-resistant uniformly porous membrane, the preparation method of which includes:

[0076] The pre-prepared polystyrene-block-poly(hydroxyethyl methacrylate) (PS-) was used. b The PHEMA homogeneous membrane was placed in a round-bottom flask. 1.5 mL of 1,1,2-trimethoxyethane and 6 mL of trifluoromethanesulfonic acid were added to the Schlenk reaction flask. The round-bottom flask and the Schlenk reaction flask were connected by a distillation elbow. The reaction apparatus was then subjected to reduced pressure. After the vacuum gauge reading stabilized, the pressure was stopped. The reaction apparatus was sealed tightly and placed in an oven at 80°C for 6 hours.

[0077] The reacted membrane was washed in a 4 mol / L NaOH solution of water and ethanol (water to ethanol volume ratio of 1:1) for 20 h to remove residual catalyst and crosslinking agent; then it was washed with pure water for 20 h to remove residual sodium hydroxide, finally obtaining a gas-phase crosslinked organic solvent resistant uniform porous membrane.

[0078] Example 11

[0079] This embodiment provides a vapor-phase crosslinked organic solvent-resistant uniformly porous membrane, the preparation method of which includes:

[0080] The pre-prepared polystyrene-block-poly(hydroxyethyl methacrylate) (PS-) was used. bThe PHEMA homogeneous membrane was placed in a round-bottom flask. 1.5 mL of 1,1,2-trimethoxyethane and 9 mL of acetic acid were added to the Schlenk reaction flask. The round-bottom flask and the Schlenk reaction flask were connected by a distillation elbow. The reaction apparatus was then subjected to reduced pressure. After the vacuum gauge reading stabilized, the pressure was stopped. The reaction apparatus was sealed tightly and placed in an oven at 80°C for 6 hours.

[0081] The reacted membrane was washed in a 4 mol / L NaOH solution of water and ethanol (water to ethanol volume ratio of 1:1) for 1 h to remove residual catalyst and crosslinking agent; then it was washed with pure water for 1 h to remove residual sodium hydroxide, finally obtaining a gas-phase crosslinked organic solvent resistant uniform porous membrane.

[0082] Example 12

[0083] This embodiment provides a vapor-phase crosslinked organic solvent-resistant uniformly porous membrane, the preparation method of which includes:

[0084] The pre-prepared polystyrene-block-poly(2-vinylpyridine) (PS-) was used. b The P2VP homogeneous membrane was placed in a round-bottom flask. 1.5 mL of 1,1,2-trimethoxyethane and 9 mL of acetic acid were added to the Schlenk reaction flask. The round-bottom flask and the Schlenk reaction flask were connected by a distillation elbow. The reaction apparatus was then subjected to reduced pressure. After the vacuum gauge reading stabilized, the pressure was stopped. The reaction apparatus was sealed tightly and placed in an oven at 80°C for 6 hours.

[0085] The reacted membrane was washed in a 4 mol / L NaOH solution of water and ethanol (water to ethanol volume ratio of 1:1) for 1 h to remove residual catalyst and crosslinking agent; then it was washed with pure water for 1 h to remove residual sodium hydroxide, finally obtaining a gas-phase crosslinked organic solvent resistant uniform porous membrane.

[0086] Comparative Example 1

[0087] This comparative example provides a liquid-phase crosslinked uniformly porous membrane, the preparation method of which includes:

[0088] Weigh 36g of ferric chloride into a 120mL tissue culture flask, add 20mL of FDA (dimethoxymethane), stir well, and let stand for 12h; weigh 36g of ferric chloride into a 50mL flask, add 20mL of FDA, stir well, and let stand for 12h; place the benzene ring-containing block copolymer homogeneous porous membrane into the above tissue culture flask, and use a dropper to draw the solution from the flask and add it dropwise onto the membrane, then seal the tissue culture flask; transfer the reaction flask to a 60℃ oven and react for 9h; after the reaction is completed, wash the membrane in a hydrochloric acid aqueous solution with pH 1 for 30min, then wash with pure water for 30min to remove hydrochloric acid, and then wash with ethanol for 30min to obtain a liquid-phase crosslinked homogeneous porous membrane.

[0089] The SEM image of the liquid-phase crosslinked uniformly porous membrane provided in this comparative example is as follows: Figure 6 As shown; the flux diagram of the liquid-phase crosslinked uniformly porous membrane provided in this comparative example is as follows. Figure 9 As shown.

[0090] Comparative Example 2

[0091] This comparative example provides a uniformly porous membrane that has not undergone crosslinking, and the method for preparing the uniformly porous membrane includes:

[0092] PS- b -P4VP block copolymers are synthesized via continuous living anionic polymerization according to a previously disclosed procedure. According to the disclosed method, a monolithic asymmetric porous membrane is prepared by a combination of block copolymer self-assembly and solvent-inducible phase inversion. Specifically, the polymer PS- b -P4VP was dissolved in a mixed solution of tetrahydrofuran / N,N-dimethylformamide (THF / DMF volume ratio 40:60; 24 wt% of total mass) to prepare a casting solution. After scraping the membrane with a doctor blade, it was left in air for a certain period (5-20 seconds) and then immersed in a non-solvent bath (water bath). The SEM image of the uniformly porous membrane provided in this comparative example is shown below. Figure 7 As shown; the SEM image of the uniformly porous membrane provided in this comparative example after immersion in DMF for 24 hours is shown below. Figure 8 As shown.

[0093] The gas-phase crosslinked organic solvent-resistant uniformly porous membrane prepared in Example 1 has an intact pore structure without collapse, and a pure water flux of 450 L / (m²). 2 Compared to the liquid-phase crosslinked uniformly porous membrane prepared in Comparative Example 1, the surface uniformly porous structure of this membrane was destroyed, the pore structure of the support layer became dense and collapsed, and the pure water flux was only 60 L / (m²). 2 (·h·bar). This demonstrates that the permeability of the vapor-phase cross-linked organic solvent-resistant uniform-porous membrane is significantly improved. Through... Figure 1 It can be seen that the membrane pore structure is intact, and through Figure 2It can be seen that the vapor-phase crosslinked membrane exhibits good resistance to organic solvents, and the pore structure did not collapse. Through... Figure 3 and Figure 4 It can be seen that the antisymmetric stretching vibration peak of CH2 after gas-phase crosslinking (2924 cm⁻¹) -1 ) and CH2 symmetric stretching vibration peak (2850cm) -1 The peak height of the benzene ring CH peak (3024 cm⁻¹) increased significantly, indicating that CH₂ was successfully introduced, while the peak height of the benzene ring CH peak (3024 cm⁻¹) was significantly increased. -1 The decrease in peak height indicates that the H on the benzene ring has been replaced by CH2, thus demonstrating the successful conduct of the cross-linking reaction. Through... Figure 5 and Figure 9 It can be seen that the flux of the gas-phase crosslinked membrane is significantly higher than that of the liquid-phase crosslinked membrane, indicating that the uniform pore layer and support layer structure of the gas-phase crosslinked membrane are not damaged, and it possesses excellent permeability. Figure 6 It can be seen that the support layer of the liquid-phase crosslinked membrane undergoes dissolution and collapse. Through... Figure 7 and Figure 8 It can be seen that the membrane without gas-phase crosslinking is not resistant to organic solvents.

[0094] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and application concept of this application, should be included within the scope of protection of this application.

Claims

1. A method for preparing a vapor-phase crosslinked organic solvent-resistant uniformly porous membrane, characterized in that, include: A block copolymer membrane containing benzene rings was placed in a mixed vapor to undergo gas-phase crosslinking, resulting in a gas-phase crosslinked organic solvent-resistant uniformly porous membrane. The mixed vapor includes gaseous alkanes containing methoxy groups and gaseous acidic substances; The gaseous acidic substances include one or more of the following: acids that are gases at room temperature and pressure, acids that are heated and vaporized, or acids that are vaporized under reduced pressure. The block copolymer homogeneous porous membrane containing benzene rings includes polystyrene-block-poly(4-vinylpyridine), polystyrene-block-poly(2-vinylpyridine), poly(tert-butylstyrene)-block-poly(4-vinylpyridine), poly(4-trimethylsilylstyrene)-block-poly(4-vinylpyridine), poly(4-methylstyrene)-block-poly(4-vinylpyridine), polystyrene-block-poly(ethylene oxide), polystyrene-block-poly(2-hydroxyethyl methacrylate), polystyrene-block-poly(glycerol methacrylate), polystyrene-block-poly(N-isopropylacrylamide), polystyrene-block-poly(acrylic acid), and polyisoprene-block-polystyrene-block-poly(4-vinylpyridine). One or more of the following: polyisoprene-block-polystyrene-block-poly(N,N-dimethylacrylamide), polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide), poly(styrene)-block-poly(4-vinylpyridine)-block-poly(propylene sulfuride), poly(4-(2-hydroxyethylthio)-2-methylbutene-copolymer-4-(2-hydroxyethylthio)-3-methylbutene-copolymer-isoprene)-block-polystyrene-block-poly(4-vinylpyridine), polystyrene-block-poly(hydroxyethyl methacrylate-2-succinoxyethyl methacrylate), or polystyrene-block-poly(hydroxyethyl methacrylate-copolymer-hydroxyethyl methacrylate-aminoacetic acid) block copolymers; The gaseous acidic substance includes one or more of hydrogen chloride, hydrogen sulfide, hydrogen cyanide, nitric acid, formic acid, acetic acid, propionic acid, butyric acid, trifluoromethanesulfonic acid, fluorosulfonic acid, or methanesulfonic acid. The gaseous methoxy-containing alkanes include one or more of the following: dimethoxymethane, 1,1-dimethoxyethane, 1,2-dimethoxyethane, 1,1,2-trimethoxyethane, 2,2-dimethoxypropane, 1,3-dimethoxypropane, 2,2-dimethoxybutane, 2,2,3-trimethoxybutane, 1,4-dimethoxybutane, 1,3-dimethoxycyclohexane, or 2,2-dimethoxypentane.

2. The preparation method according to claim 1, characterized in that, The method for preparing the mixed vapor includes: A mixture of methoxyl-containing alkanes and acidic substances is vaporized to produce a mixed vapor. The mixed gasification method includes any one of ambient temperature and pressure gasification, heating gasification, depressurization gasification, or heating and depressurization gasification.

3. The preparation method according to claim 1, characterized in that, The temperature for gas-phase crosslinking is from 20°C to 100°C; the time for gas-phase crosslinking is from 0.1 h to 96 h.

4. The preparation method according to claim 2, characterized in that, The volume ratio of the methoxylated alkane to the acidic substance is (0.1-1.2):(3-9).

5. The preparation method according to claim 2, characterized in that, The mass ratio of the methoxyl-containing alkane to the block copolymer membrane containing a benzene ring is 1:10 to 60:

1.

6. The preparation method according to claim 1, characterized in that, The gas-phase crosslinking process further includes washing with sodium hydroxide solution and water; the concentration of the sodium hydroxide solution is from 0.1 mol / L to 10 mol / L.

7. The preparation method according to claim 6, characterized in that, The washing time with sodium hydroxide solution is 1 hour to 120 hours; the washing time with water is 1 hour to 120 hours.

8. A vapor-phase crosslinked organic solvent-resistant uniformly porous membrane, characterized in that, It is prepared according to the preparation method according to any one of claims 1 to 7.

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