A high specific surface area polyurethane self-porous material and its preparation method

Abstract

This invention discloses a high specific surface area polyurethane self-contained microporous material and its preparation method. It uses polyisocyanates and polyols containing rigid twisted groups as monomers, tertiary amine compounds as catalysts, and acetone or N,N'-dimethylformamide as the reaction medium, and is prepared by stepwise polymerization under static or agitated conditions. The system of this invention has a simple composition, low reaction temperature (30℃), fast reaction rate (<3 hours), and high polymer yield (98%). Furthermore, the polymerization reaction can be carried out under static, unstirred conditions without any stirring or agitation equipment, significantly reducing production costs and energy consumption. Post-treatment of the product using supercritical liquid extraction technology significantly increases the material's specific surface area (up to 900 m²). 2 The resulting material is rich in hydroxyl and amino groups, and exhibits strong interactions with gases such as CO2, showing potential applications in gas adsorption and separation.

Description

Technical Field

[0001] This invention relates to a self-contained microporous material, specifically a high specific surface area polyurethane self-contained microporous material and its preparation method. It belongs to the technical field of functional polymer materials. Background Technology

[0002] Porous polymers (PIMs) are a newly emerging type of organic microporous material based on aromatic spirocyclic rings, showing broad application prospects in gas separation, hydrogen storage, and catalysis. PIMs are typically thermally stable amorphous glassy polymers containing a spirocenter (two rings sharing a single atom), exhibiting a non-planar, twisted, and rigid molecular structure. This prevents the polymer backbone from rotating freely, hindering effective chain stacking and forming a continuous microporous structure within the material. Due to the numerous vacancies and loose molecular structure within PIM membranes, they are widely recognized as the most promising materials for gas transport and separation membranes.

[0003] Currently, existing reports all describe the preparation of PIMs using functional monomers containing tortuous and rigid structures.

[0004] Budd PM et al. (Adv. Mater., 2004, Vol. 16, pp. 456-459) prepared the first self-microporous polymer PIM-1 by using dimethylformamide (DMF) as a solvent and reacting a rigid monomer containing tetrafluorophenyl and a tetrahydroxy monomer containing a spirocyclic ring at 65°C for 72 hours.

[0005] Ghanem BS et al. (Macromolecules, 2008, Vol. 41, pp. 1640–1646) used spirobisindane and ethyl anthracene compounds as monomers, first reacting them at 150 °C for 48 h in a mixed system containing K2CO3, 18-crown ether-6 and DMF, and then followed by precipitation, washing and drying steps to obtain a series of PIMs with a yield not exceeding 80% and a maximum specific surface area of ​​720 m2 / g.

[0006] Stefanie A et al. (Macromolecules, 2011, Vol. 44, pp. 976–980) synthesized a series of aromatic polyimides (PIMs) using diaminotriterene and different types of phthalic anhydride as monomers at 80 and 180 °C for 4 and 16 h, respectively. The PIMs had a specific surface area of ​​430 m² / g and a yield of approximately 90%.

[0007] Swaidan R et al. (J. Membr. Sci., 2014, Vol. 457, pp. 95–102) modified PIM-1 with hydroxylamine and prepared AO-PIM-1 containing a methylamine oxime group by reacting at 69 °C for 20 h. The specific surface area was about 480 m2 / g.

[0008] Zhang G et al. (J. Membr. Sci., 2018, Vol. 556, pp. 277–284) prepared PIM containing tripterene and tergler bases by copolymerizing diaminotripterene with 2,6-diamino-14-carboxytripterene. The entire process took at least 5 days and the yield was less than 70%.

[0009] Ainur Y et al. (J. Membr. Sci., 2020, Vol. 595, p. 117512) first used 2,6(7)-dihydroxy-3,7(6)-diaminotriptene and 4,4-hexafluoroisopropenyl phthalic anhydride as monomers and reacted them at 200 °C for 4 h. Then, after drying and heat treatment (>30 h), functionalized polyimide PIM with a specific surface area of ​​405 m2 / g was obtained.

[0010] Patent CN110862537B first prepares the biphenylamine monomer by reacting maleimide or its derivative with 2,6-diaminoanthracene via the Diels-Alder reaction, then uses the Tegler base reaction to cause the biphenylamine monomer to undergo polycondensation, and finally removes maleimide or its derivative to obtain PIM. The entire process takes at least 18 hours, and the specific surface area of ​​the product is between 50 and 800 m2 / g.

[0011] Patent CN106279672B discloses a method for preparing PIM. First, two tetraphenol monomers and terephthalonitrile are used as raw materials to carry out a polycondensation reaction at 120-160°C in a protective atmosphere. Then, precipitation and washing are performed. The resulting yellow solid is boiled in boiling water for 5-8 hours and then vacuum dried at 80°C for 20 hours to obtain the target product with a specific surface area between 560 and 760 m2 / g.

[0012] In summary, existing methods for preparing PIMs involve cumbersome steps, high reaction temperatures, and long reaction times (≥18 hours), while typically resulting in low specific surface areas. Polyurethane materials, on the other hand, offer easily tunable properties and generally possess advantages such as high strength, high toughness, wear resistance, oil resistance, radiation resistance, and good air permeability. Furthermore, their raw materials are widely available, and the reaction conditions are mild with relatively fast reaction rates. It is noteworthy that no reports of polyurethane materials possessing inherent microporous structures have been found in existing literature and patent documents. Summary of the Invention

[0013] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high specific surface area polyurethane material with microporous structure and its preparation method, which is simple, fast and efficient.

[0014] To achieve the above objectives, the present invention adopts the following technical solution: 1. A method for preparing a high specific surface area polyurethane self-porous material, comprising the following steps: first, dissolving polyisocyanate monomers, polyol functional monomers and catalysts in a reaction medium, then carrying out a polymerization reaction in a constant temperature water bath shaker to obtain a reaction product, and finally treating the reaction product by alternating supercritical liquid extraction and organic solvent soaking to obtain the polyurethane self-porous material, wherein the specific surface area is between 500 and 900 m2 / g and the average pore size is 0.6 to 1.9 nm.

[0015] Preferably, the polymerization process conditions are: reaction temperature 20-95℃, oscillation frequency 0-300 osc / min, and oscillation time 15-180 minutes.

[0016] Further preferred methods include a reaction temperature of 30–85°C, an oscillation frequency of 0–200 osc / min, and an oscillation time of 30–120 minutes.

[0017] Preferably, the total amount of polyisocyanate monomers and polyol functional monomers is 1.0 to 40.0% of the total mass of the entire system, more preferably 5.0 to 30.0%; the molar ratio of isocyanate groups in the polyisocyanate monomers to hydroxyl groups in the polyol monomers is 0.7 to 1.3:1, more preferably 0.8 to 1.2:1; and the amount of catalyst is 0.01 to 5.0% of the total mass of all monomers, more preferably 0.1 to 2.0%.

[0018] Preferably, the polyisocyanate monomer is selected from any one of the following: phthalic diisocyanate, isophthalic diisocyanate, terephthalic diisocyanate, toluene diisocyanate, 4,4'-diisocyanate-3,3'-dimethylbiphenylmethane, naphthalene diisocyanate, 4,4-diphenylmethane diisocyanate, triphenylmethane triisocyanate, 2,2-bis(4-phenylisocyanate)hexafluoropropane, triterene diisocyanate, and more preferably isophthalic diisocyanate, toluene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, 2,2-bis(4-phenylisocyanate)hexafluoropropane, and triterene diisocyanate.

[0019] Preferably, the polyol functional monomer is selected from any one of the following: 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane, 6,6'-dihydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane, dihydroxynaphthalene, 9,10-dimethyl-2,3,6,7-tetrahydroxyanthracene, 9,9-bis(3,4-dihydroxyphenyl)fluorene, 1,2,4,5-tetrahydroxybenzene, 5,5',6,6'-tetrahydroxy-3,3'-diketone-spirobisindane, 9,10-dimethyl-9,10-ethyleneanthracene-2,3,6 7-Tetraphenol, 6,6',7,7'-tetrahydroxy-4,4,4',4'-tetramethyl-2,2'-spirobisbenzodihydropyran, and more preferably 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane, 9,10-dimethyl-2,3,6,7-tetrahydroxyanthracene, 9,9'-bis(3,4-dihydroxyphenyl)fluorene, 5,5',6,6'-tetrahydroxy-3,3'-dione-spirobisindane, 6,6',7,7'-tetrahydroxy-4,4,4',4'-tetramethyl-2,2'-spirobisbenzodihydropyran.

[0020] Preferably, the catalyst is a tertiary amine compound or / and an organometallic compound, more preferably triethylamine, triethylenediamine, N-ethylmorpholine, dibutyltin dilaurate, stannous octoate, zirconium acetylacetonate or / and bismuth carboxylate.

[0021] Preferably, the reaction medium is acetone, butanone, acetonitrile, dimethyl sulfoxide, dioxane, pyridine, tetrahydrofuran, chloroform, ethyl acetate, N,N'-dimethylformamide, N,N'-dimethylacetamide or / and N-methylpyrrolidone, and more preferably acetone, butanone, acetonitrile, dimethyl sulfoxide or / and N,N'-dimethylformamide.

[0022] Preferably, the alternating treatment method is as follows: the reaction product is placed in a sealed container and supercritical CO2 is introduced. After extraction at 30-50 °C and 8-50 MPa for 5-20 minutes, the gas is released to obtain a solid. The solid is soaked in an organic solvent and then extracted and released again. This process is repeated 1-3 times. The organic solvent is acetone, butanone, or acetonitrile.

[0023] 2. A high specific surface area polyurethane material with microporous structure is prepared by the aforementioned method.

[0024] The beneficial effects of this invention are: This invention utilizes polyisocyanates and polyols containing rigid, twisted groups as monomers, tertiary amine compounds as catalysts, and acetone or N,N'-dimethylformamide as the reaction medium to synthesize polyurethane microporous materials through stepwise polymerization under static or agitated conditions. The system of this invention features a simple composition, low reaction temperature (30 °C), fast reaction rate (<3 hours), high polymer yield (98%), and the polymerization reaction can be carried out under static, unstirred conditions without any stirring or agitation equipment, significantly reducing production costs and energy consumption. Post-treatment of the product using supercritical liquid extraction technology significantly increases the specific surface area of ​​the material (up to 900 m² / g). The resulting material is rich in hydroxyl and amino groups, exhibiting strong interactions with gases such as CO₂, and has potential applications in gas adsorption and separation.

[0025] The polyurethane microporous material prepared by this invention has a yield between 90% and 98%, a specific surface area between 500 and 900 m² / g, and an average pore size between 0.6 and 1.9 nm. The specific surface area and pore structure of the product can be adjusted by regulating the ratio and amount of monomer and solvent, reaction temperature, and other conditions to meet the material performance requirements of different applications.

[0026] The applicant has been engaged in the preparation and characterization of porous polymer materials, focusing on improving the specific surface area of ​​porous materials. In previous work (Journal of Chemical Research in Chinese Universities, 2013, Vol. 34, pp. 992-999; CN103819650B), the applicant synthesized polyurea porous materials (PPU) in a mixed solvent of water and acetone, using toluene diisocyanate or a mixture of 2-4 isocyanates as monomers, based on their reaction with water. This material does not contain micropores smaller than 2 nm, and is mainly composed of mesopores of 3-5 nm and macropores larger than 100 nm, with a surface area not exceeding 190 m² / g. Due to the use of aromatic isocyanate monomers containing benzene rings and the strong hydrogen bonding between urea groups, the resulting PPU molecular chains have strong rigidity and interaction, causing the molecular chains to attract each other and aggregate to form fibrous aggregates. Because no functional monomers with twisted structures are introduced, the PPU molecular chains are tightly packed, resulting in no gaps between the chains and no microporous structure. The internal mesopores and macropores are formed by overlapping fibrous aggregates. Due to the large pore size, the specific surface area of ​​PPU is relatively low. The applicant has also conducted experiments under the same conditions using aliphatic isocyanate monomers without benzene rings (such as isophorone diisocyanate), obtaining polymer microspheres with smooth surfaces and no pores (CN102643402B, CN102702470B and CN104072719B). This also indicates that the porous structure of PPU is related to its rigid structure (benzene rings). When aliphatic isocyanate monomers are used, the introduction of non-rigid alkyl chains increases the flexibility of the molecular chains, resulting in a tighter arrangement and packing of the molecular chains, thus eliminating the porous structure. The applicant also previously used polyisocyanates and aliphatic amines such as triethylenetetramine as monomers to prepare cross-linked polyureas (CN106317358B) in mixed solvents of water / acetonitrile or water / acetone. The results showed that regardless of whether the isocyanate monomer contained a rigid structure, the product obtained from its reaction with aliphatic polyamines was always a smooth-surfaced polyurea microsphere, lacking a porous structure. This indicates that even using rigid isocyanates and aliphatic polyamine monomers cannot produce porous materials. The reason may be that the introduction of aliphatic polyamines increases the flexibility of the polyurea molecular chains, making it easier for the molecular chains to adjust their conformation and form a more compact arrangement and stacking, thus making it difficult to form pores. In terms of polyurethane materials, the applicant used polyisocyanates and aliphatic polyols such as pentaerythritol as monomers to prepare crosslinked polyurethanes in a mixed solvent of water / acetonitrile or water / acetone (CN106317358B). The results also showed that, regardless of whether the isocyanate monomer contained a rigid structure, the product obtained by reacting it with aliphatic polyols was also a smooth polyurethane microsphere without a porous structure, for the same reason as when using aliphatic polyamines.

[0027] Recently, the applicant attempted to react hydroxyl-containing spirobisindane with polyisocyanates and found that the surface area of ​​the material far exceeded expectations (>500 m² / g), obtaining unexpected results. Based on this, the applicant systematically optimized the experimental conditions of the system, including the type, amount, and ratio of the polyisocyanate containing a rigid, twisted structure and the polyol monomer, the type, amount, and ratio of the solvent, the reaction temperature, and the stirring rate. Through numerous innovative experiments, the specific surface area of ​​the material reached 900 m² / g. Significantly different from other works mentioned above, this invention, in preparing polyurethane porous materials, uses not only polyisocyanate monomers containing rigid structures but also polyol monomers containing both rigid and twisted structures. The rigid structure in the molecule prevents the chain segments from rotating freely, while the twisted structure hinders the close packing of macromolecular chains, promoting the formation of a continuous microporous structure (<2 nm) within the polyurethane, which endows the material with a high specific surface area. The resulting polyurethane is a typical self-porous material. The structure, type, and pore-forming mechanism of the raw materials used are substantially different from other polyurea and polyurethane porous materials mentioned above. Furthermore, there are no reports on self-porous polyurethane materials in existing literature or patent documents, and no relevant methods or technical inspirations are available for reference. Compared with existing methods for preparing PIM, the method of this invention requires only a single raw material, operates under low temperature conditions (20~80 ℃, static or stirring rate below 300 r / min), has a shorter reaction time (<3 h), and produces a product with a high specific surface area (900 m² / g). In summary, this invention has significant inventiveness.

[0028] Supercritical liquid extraction (SLI) is a novel chemical separation technology that has emerged in the last 30 years and has been widely applied in many fields. The applicant discovered that using SLI significantly increases the specific surface area of ​​the resulting microporous material. Supercritical liquids (such as CO2) can extract the reaction medium in the system. During the venting process, the solvent is rapidly released with the CO2, which shortens the desolvation time of the polyurethane molecular chains during drying. This prevents the molecular chains from fully relaxing, resulting in a looser packing effect, which is beneficial for increasing the specific surface area of ​​the material. The applicant optimized the conditions of supercritical fluid extraction (including temperature, pressure, and time) through extensive experiments and compared the results with those obtained without this technology. The results showed that when the product was post-processed using conventional methods (including centrifugation, washing, and drying, see comparative examples), the yield of the obtained polyurethane microporous material was 92.4%, with a specific surface area of ​​720 m² / g (significantly higher than the specific surface area of ​​the polyurea porous material previously reported, i.e., 190 m² / g in CN103819650B), and an average pore size of 1.4 nm. However, when post-processed using supercritical liquid extraction (Example 1), the yield of the obtained polyurethane microporous material was 95.4%, with a specific surface area of ​​898 m² / g and an average pore size of 0.6 nm. Therefore, the specific surface area of ​​the product is further improved after using supercritical liquid extraction.

[0029] The specific advantages are as follows: 1. The polyol functional monomers required by this invention are commonly used raw materials in the preparation of PIMs. The required polyisocyanate monomers are commercially available and easy to obtain. At the same time, the method has a low reaction temperature, mild conditions, simple operation and fast reaction rate. The whole process can be carried out at room temperature and the reaction time does not exceed 3 hours, which has obvious advantages compared with the previous methods (above 100°C, >18 hours).

[0030] 2. This invention employs supercritical extraction technology to post-process PIMs, which significantly increases the specific surface area of ​​the material (up to 900 m2 / g, see Example 1 and Comparative Example). At the same time, the material surface is rich in hydroxyl and amino groups, which have strong interactions with gases such as CO2, making it a potential application in the fields of selective adsorption and separation of gases.

[0031] 3. The monomer dosage in the preparation of polyurethane PIMs by this invention can reach 40%, and the monomer conversion rate can reach 98%. The efficiency of PIMs preparation is significantly improved compared with previous methods. At the same time, the polymerization reaction can be carried out under static and unstirred conditions, that is, the reactor only needs to be placed in a constant temperature water bath without any stirring or shaking equipment, which makes the production cost and energy consumption significantly lower. Detailed Implementation

[0032] The present invention will be further described below with reference to embodiments. It should be noted that the following description is only for explaining the present invention and does not limit its content.

[0033] Example 1

[0034] At room temperature, 90.0 g of N,N'-dimethylformyl was added to a 120 mL reaction flask, followed by 0.1 g of triethylenediamine, 3.36 g of 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane, and 6.64 g of triterene diisocyanate (NCO / OH = 1.0). After shaking thoroughly, the reaction flask was placed in a constant temperature water bath at 85 °C for 30 min. After the reaction was complete, the product was placed in a sealed container and supercritical CO2 was introduced. Extraction was performed at 35 °C and 35 MPa for 15 min, followed by venting. The resulting solid was then soaked in acetonitrile and extracted and vented again. This process was repeated twice to obtain a polyurethane microporous material with a yield of 95.4%, a specific surface area of ​​898 m² / g, and an average pore size of 0.6 nm.

[0035] Example 2

[0036] At room temperature, 95.0 g of acetone was added to a 120 mL reaction flask, followed by 0.1 g of dibutyltin dilaurate, 2.97 g of 6,6'-dihydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane, and 2.09 g of naphthalene diisocyanate (NCO / OH = 1.0). After shaking thoroughly, the reaction flask was placed in a 30 °C constant temperature water bath shaker and reacted for 120 min at a shaking rate of 60 osc / min. After the reaction, the product was placed in a sealed container and supercritical CO2 was introduced. Extraction was performed at 35 °C and 30 MPa for 20 min, followed by venting. The resulting solid was then soaked in acetone and extracted and vented again. This process was repeated three times to obtain a polyurethane microporous material with a yield of 90.4%, a specific surface area of ​​585 m² / g, and an average pore size of 1.5 nm.

[0037] Example 3

[0038] At room temperature, 80.0 g of dimethyl sulfoxide was added to a 120 mL reaction flask, followed by 0.04 g of triethylamine, 0.06 g of zirconium acetylacetonate, 7.60 g of 9,10-dimethyl-2,3,6,7-tetrahydroxyanthracene, and 12.40 g of triphenylmethane triisocyanate (NCO / OH = 0.9). After shaking to ensure homogeneity, the reaction flask was placed in a constant temperature water bath at 70 °C for 40 min. After the reaction was complete, the product was placed in a sealed container and supercritical CO2 was introduced. Extraction was performed at 35 °C and 40 MPa for 10 min, followed by venting. The resulting solid was then soaked in butanone and extracted and vented again. This process was repeated twice to obtain a polyurethane microporous material with a yield of 97.4%, a specific surface area of ​​654 m² / g, and an average pore size of 1.1 nm.

[0039] Example 4

[0040] At room temperature, 70.0 g of a 2 / 8 mass ratio (acetonitrile / N,N'-dimethylformamide) mixed solvent was added to a 120 mL reaction flask, followed by 0.15 g of N-ethylmorpholine, 5.26 g of 1,2,4,5-tetrahydroxybenzene, and 24.74 g of 4,4'-diisocyanate-3,3'-dimethylbiphenylmethane (NCO / OH = 1.2). After thorough shaking, the flask was placed in a 50 °C water bath shaker and reacted for 60 min at a shaking rate of 120 osc / min. After the reaction, the product was placed in a sealed container and supercritical CO2 was introduced. Extraction was performed at 40 °C and 40 MPa for 5 min, followed by venting. The resulting solid was then soaked in acetonitrile and extracted and vented again. This process was repeated twice to obtain a polyurethane microporous material with a yield of 97.8%, a specific surface area of ​​515 m² / g, and an average pore size of 1.8 nm.

[0041] Example 5

[0042] At room temperature, 70.0 g of a 5 / 5 acetone / dimethyl sulfoxide mixed solvent was added to a 120 mL reaction flask, followed by 0.3 g of triethylamine, 9.90 g of 5,5',6,6'-tetrahydroxy-3,3'-diketone-spirobine, and 20.10 g of 2,2-bis(4-phenyl isocyanate)hexafluoropropane (NCO / OH = 0.9). After shaking thoroughly, the reaction flask was placed in a constant temperature water bath at 30 °C for 120 min. After the reaction was complete, the product was placed in a sealed container and supercritical CO2 was introduced. Extraction was performed at 40 °C and 40 MPa for 5 min, followed by venting. The resulting solid was then soaked in acetone and extracted and vented again. This process was repeated three times to obtain a polyurethane microporous material with a yield of 97.4%, a specific surface area of ​​854 m² / g, and an average pore size of 0.7 nm.

[0043] Example 6

[0044] At room temperature, 80.0 g of a 5 / 5 mass ratio acetonitrile / butanone mixed solvent was added to a 120 mL reaction flask, followed by 0.4 g of stannous octoate, 10.88 g of 9,9-bis(3,4-dihydroxyphenyl)fluorene, and 9.12 g of isophthalic diisocyanate (NCO / OH = 1.0). After shaking thoroughly, the flask was placed in an 85 °C constant temperature water bath shaker and reacted for 30 min at a shaking rate of 200 osc / min. After the reaction was completed, the product was placed in a sealed container and supercritical CO2 was introduced. Extraction was performed at 40 °C and 35 MPa for 10 min, followed by venting. The resulting solid was then soaked in butanone and extracted and vented again. This process was repeated twice to obtain a polyurethane microporous material with a yield of 95.5%, a specific surface area of ​​723 m² / g, and an average pore size of 0.9 nm.

[0045] To compare with the material obtained by post-processing with supercritical CO2 according to the present invention (Example 1), a comparative example of post-processing the product using conventional methods is given below.

[0046] Comparative Example Stepwise polymerization was carried out using the same formulation and steps as in Example 1: At room temperature, 90.0 g of N,N'-dimethylformyl was added to a 120 mL reaction flask, followed by 0.1 g of triethylenediamine, 3.36 g of 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane, and 6.64 g of triterene diisocyanate (NCO / OH=1.0). After shaking evenly, the reaction flask was placed in a constant temperature water bath at 85 °C for 30 min.

[0047] The product was post-processed using conventional methods: after the reaction was completed, the system was centrifuged at 10000 r / min for 8 min. After removing the supernatant, the product was washed with N,N'-dimethylformyl and centrifuged again. This process was repeated twice. The resulting product was then dried in an 85 ℃ constant temperature oven for 24 h to obtain polyurethane microporous material with a yield of 92.4%, a specific surface area of ​​720 m2 / g, and an average pore size of 1.4 nm.

[0048] Compared with Example 1, the comparative example had a longer post-processing time, significantly lower yield and specific surface area, and larger pore size.

[0049] While the specific embodiments of the present invention have been described above, they are not intended to limit the scope of protection of the present invention. Based on the technical solutions of the present invention, various modifications or variations that can be made by those skilled in the art without creative effort are still within the scope of protection of the present invention.

Claims

1. A process for the preparation of a high specific surface polyurethane self- microporous material, characterized in that, The specific steps are as follows: First, the polyisocyanate monomer, polyol functional monomer, and catalyst are dissolved in the reaction medium. Then, a polymerization reaction is carried out in a constant temperature water bath shaker to obtain the reaction product. Finally, the reaction product is subjected to alternating treatments of supercritical CO2 extraction and organic solvent soaking to obtain the polyurethane microporous material with a specific surface area between 500 and 900 m². 2 The average pore size is between 0.6 and 1.9 nm. The polyisocyanate monomer is selected from any one of the following: ortho-phenyl diisocyanate, iso-phenyl diisocyanate, terephthalic diisocyanate, toluene diisocyanate, 4,4'-diisocyanate-3,3'-dimethylbiphenylmethane, naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, triphenylmethane triisocyanate, 2,2-bis(4-phenylisocyanate)hexafluoropropane, and triterpenoid diisocyanate; The polyol functional monomer is selected from any one of the following: 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane, 6,6'-dihydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane, 9,10-dimethyl-2,3,6,7-tetrahydroxyanthracene, 9,9-bis(3,4-dihydroxyphenyl)fluorene, 1,2,4,5-tetrahydroxybenzene, 9,10-dimethyl-9,10-ethylhexane-2,3,6,7-tetraphenol, 6,6',7,7'-tetrahydroxy-4,4,4',4'-tetramethyl-2,2'-spirobisbenzodihydropyran.

2. The production method according to claim 1, characterized by, The polymerization process conditions are as follows: reaction temperature 20–95℃, oscillation frequency 0–300 osc / min, and oscillation time 15–180 minutes.

3. The production method according to claim 2, characterized by, The reaction temperature is 30–85℃, the oscillation frequency is 0–200 osc / min, and the oscillation time is 30–120 minutes.

4. The method of claim 1, wherein, The total amount of polyisocyanate monomers and polyol functional monomers is 1.0 to 40.0% of the total mass of the whole system; the molar ratio of isocyanate groups in polyisocyanate monomers to hydroxyl groups in polyol monomers is 0.7 to 1.3:1; the amount of catalyst is 0.01 to 5.0% of the total mass of all monomers.

5. The preparation method according to claim 1, characterized in that, The catalyst is a tertiary amine compound and / or an organometallic compound.

6. The method of claim 1, wherein, The reaction medium is acetone, butanone, acetonitrile, dimethyl sulfoxide, dioxane, pyridine, tetrahydrofuran, chloroform, ethyl acetate, N,N-dimethylformamide, N,N-dimethylacetamide, or / and N-methylpyrrolidone.

7. The preparation method according to claim 1, characterized in that, The specific method of alternating treatment is as follows: the reaction product is placed in a sealed container and supercritical CO2 is introduced. After extraction at 30-50 °C and 8-50 MPa for 5-20 minutes, the gas is released to obtain a solid. The solid is soaked in an organic solvent and then extracted and released again. This process is repeated 1-3 times. The organic solvent is acetone, butanone, or acetonitrile.

8. A high specific surface polyurethane self-microporous material, characterized in that, It is prepared by the method described in any one of claims 1 to 7.