阅读说明：本技术 一类含六甲基取代结构可溶性聚酰亚胺及其制备方法和应用 (Soluble polyimide containing hexamethyl substitution structure and preparation method and application thereof ) 是由 汪称意 蒋彩荣 余彬 朱冠南 华广洲 赵晓燕 李坚 任强 于 2021-01-13 设计创作，主要内容包括：本发明属于高性能芳香型聚合物及其制备领域,特别涉及一类含六甲基取代结构可溶性聚酰亚胺及其制备方法,其制备方法为：将等物质量的含六甲基取代对称结构的芳香二胺单体和商品化芳香二酐单体加入有机溶剂中,在催化剂作用下,于170～200℃搅拌反应5-10h后,结束反应,经过沉降、洗涤和干燥,即可得到纤维状的含六甲基取代对称结构可溶性聚酰亚胺聚合物。该类聚酰亚胺在特定溶剂中的溶解度可达10wt％以上,具有优异的成膜性。该类聚酰亚胺可以应用于制备聚酰亚胺聚合物薄膜,用于气体分离膜材料,在气体分离领域具有潜在应用价值。(The invention belongs to the field of high-performance aromatic polymers and preparation thereof, and particularly relates to soluble polyimide containing a hexamethyl substitution structure and a preparation method thereof, wherein the preparation method comprises the following steps: adding equal mass of aromatic diamine monomer containing hexamethyl substitution symmetric structure and commercial aromatic dianhydride monomer into organic solvent, stirring and reacting for 5-10h at 170-200 ℃ under the action of catalyst, finishing the reaction, settling, washing and drying to obtain the fibrous soluble polyimide polymer containing hexamethyl substitution symmetric structure. The solubility of the polyimide in a specific solvent can reach more than 10 wt%, and the polyimide has excellent film forming property. The polyimide can be applied to preparing polyimide polymer films and gas separation film materials, and has potential application value in the field of gas separation.)

1. The soluble polyimide containing the hexamethyl substitution structure is characterized in that a structural unit of the soluble polyimide contains the hexamethyl structure, and the structural formula of the soluble polyimide is as follows:

wherein the content of the first and second substances,is composed ofWherein the repeating unit n is 40 to 100.

2. The soluble polyimide with hexamethyl substitution according to claim 1, wherein the polyimide is selected from the group consisting of polyimide with CO gas at 30 ℃ and 100kPa₂、CH₄、N₂The transmission coefficients of the light-emitting element are respectively between 77.1 to 91.3 barrers, 2.8 to 4.7 barrers and 5.4 to 8.2 barrers, and the transmittance to CO is₂/CH₄And CO₂/N₂The separation coefficients of (a) are respectively between 19.43 and 29.16 and 11.13 and 15.32.

3. The soluble polyimide with a hexamethyl substitution structure as claimed in claim 1, wherein the glass transition temperature of the polyimide is 279 to 313 ℃, and the 10% weight loss under nitrogen and air temperature ranges are 508 to 517 ℃ and 435 to 461 ℃, respectively.

4. The method for preparing soluble polyimide containing hexamethyl substitution structure according to claim 1, comprising the steps of:

adding equal amount of aromatic diamine monomer and aromatic dianhydride monomer containing hexamethyl substitution structure into organic solvent under the protection of nitrogen, adding catalyst, heating to 170-200 ℃ for reaction for 5-10h to obtain viscous and transparent polymer solution, finishing the reaction, pouring the polymer solution into ethanol for settling, filtering, washing and drying to obtain the fibrous polyimide polymer containing hexamethyl substitution structure.

5. The method as claimed in claim 4, wherein the aromatic diamine monomer containing hexamethyl substitution is 4, 6-bis- (2,4, 6-trimethyl-phenoxy) -1, 3-diaminobenzene, and the structural formula is:

。

6. the method for preparing soluble polyimide with hexamethyl substitution structure as claimed in claim 4, wherein said dianhydride monomer is one of biphenyl tetracarboxylic dianhydride, diphenyl ether tetracarboxylic dianhydride, and benzophenone tetracarboxylic dianhydride.

7. The method for preparing soluble polyimide with a hexamethyl substitution structure as claimed in claim 4, wherein the organic solvent is m-cresol or N-methylpyrrolidone, and the mass of the solvent is 5 to 10 times of the total mass of the diamine monomer and the dianhydride monomer.

8. The method according to claim 4, wherein the catalyst is isoquinoline in an amount of 1 to 3% based on the amount of the diamine monomer.

9. The application of the soluble polyimide containing the hexamethyl substitution structure as claimed in claim 1, which is characterized in that the soluble polyimide is applied to the preparation of a gas separation membrane material, wherein the gas separation membrane material is a polyimide membrane material containing the hexamethyl substitution structure.

10. The use of the soluble polyimide containing a hexamethyl substitution structure as claimed in claim 9, wherein the preparation method of the polyimide film material comprises the following steps:

adding a polyimide polymer containing a hexamethyl substitution structure into a proper amount of organic solvent to prepare a solution with the weight percent of 5-10%, filtering, casting and coating, and vacuum-drying at 60-100 ℃ for 12-24 h to obtain the corresponding polyimide film material containing the hexamethyl substitution structure.

Technical Field

The invention belongs to the field of high-performance aromatic polymers and preparation thereof, and particularly relates to soluble polyimide containing a hexamethyl substitution structure, and a preparation method and application thereof.

Background

Aromatic polyimides are an important class of high-performance materials, which are used in a wide variety of fields because of their excellent combination of properties. When used as a gas separation membrane, the polyimide film shows high gas selectivity, and CO is used in the industrial field₂Capture of natural gas, purification of natural gas and N₂Has high application value in the aspects of adsorption and the like. However, commercially available polyimides generally have low gas permeability (e.g., Kapton films for CO)₂And O₂Respectively, of only 3.51 and 5.82barrer), it is difficult to meet the development requirements of high-efficiency rapid gas separation equipment. In addition, the membrane separation is often performed in a complex environment such as a high temperature environment during the application, which requires that the polymer has excellent heat resistance and aging resistance. On the other hand, polyimide is difficult to dissolve and infusible due to the structural rigidity and strong intermolecular force, and is difficult to process, so that the polyimide becomes a technical challenge in the practical application process. Therefore, it is of great research significance to design and develop polyimide film materials with good solubility, heat resistance and gas separation performance.

Researches find that the free volume of the polymer can be effectively increased by introducing a large substituent side group structure into the molecular structure of the polyimide, so that the solubility, film forming property, gas permeability and the like of the polymer are improved. Due to structural design and synthetic challenges, introducing multiple bulky substituents to modify polyimides often presents great difficulties.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Disclosure of Invention

Aiming at the defects, the invention improves the dissolution and film-forming properties of polyimide polymers and further improves the gas separation performance of polymer films, designs and prepares polyimide containing hexamethyl substitution structures based on molecular design, and introduces hexamethyl substitution structures with large free volume into the main chain of polymer molecules, thereby improving the dissolution performance of polyimide and endowing the polyimide with excellent film-forming properties on one hand, and further improving the gas permeability of polyimide film materials on the other hand, so that the polyimide polymers have important potential application values in the field of film separation.

In order to realize the purpose, the invention is realized by the following technical scheme:

the structural unit of the soluble polyimide contains a hexamethyl structure, and the structural formula of the soluble polyimide is as follows:

wherein the content of the first and second substances,is composed ofWherein the repeating unit n is 40 to 100.

The soluble polyimide containing the hexamethyl substitution structure is prepared at the temperature of 30 ℃ and the pressure of 100kPaFor different gases of CO₂、CH₄、N₂The transmission coefficients of the light-emitting element are respectively between 77.1 to 91.3 barrers, 2.8 to 4.7 barrers and 5.4 to 8.2 barrers, and the transmittance to CO is₂/CH₄And CO₂/N₂The separation coefficients of (A) are respectively between 19.43 and 29.16 and between 11.13 and 15.32; the glass transition temperature ranges from 279 ℃ to 313 ℃, and the 10% thermal weight loss temperature ranges from 508 ℃ to 517 ℃ and from 435 ℃ to 461 ℃ under nitrogen and air respectively.

The invention also provides a preparation method of the soluble polyimide polymer containing the hexamethyl substitution structure, which comprises the following specific steps:

adding equal amount of aromatic diamine monomer and aromatic dianhydride monomer containing hexamethyl substitution structure into organic solvent under the protection of nitrogen, adding catalyst, heating to 170-200 ℃ for reaction for 5-10h to obtain viscous and transparent polymer solution, finishing the reaction, pouring the polymer solution into ethanol for settling, filtering, washing and drying to obtain the fibrous polyimide polymer containing hexamethyl substitution structure.

In the above preparation method, the aromatic diamine monomer containing a hexamethyl substitution structure is 4, 6-bis- (2,4, 6-trimethyl-phenoxy) -1, 3-diaminobenzene, and the structural formula is:

in the preparation method, the dianhydride monomer is one of diphenyl ether tetracarboxylic dianhydride, biphenyl tetracarboxylic dianhydride or benzophenone tetracarboxylic dianhydride.

In the preparation method, the organic solvent is m-cresol or N-methyl pyrrolidone, and the mass of the solvent is 5-10 times of the total mass of the diamine monomer and the dianhydride monomer; the catalyst is isoquinoline, and the dosage of the catalyst is 1-3% of the material of the diamine monomer.

The specific synthetic route of the soluble polyimide polymer containing the hexamethyl substitution structure is as follows:

the invention also provides an application of the soluble polyimide containing the hexamethyl substitution structure, which is the preparation of a gas separation membrane material, wherein the gas separation membrane material is the polyimide membrane material containing the hexamethyl substitution structure, and the membrane material has good dissolving and film-forming properties, excellent high-temperature resistance and higher gas permeability and can be applied to the field of membrane separation.

The preparation method of the polyimide film material comprises the following steps:

adding the polyimide polymer containing the hexamethyl substitution structure into a proper amount of organic solvent to prepare a solution with the weight percent of 5-10, filtering, casting a coating film, and drying in vacuum at the temperature of 60-100 ℃ for 12-24 hours to obtain the corresponding polyimide film material containing the hexamethyl substitution structure. The organic solvent is N-methyl pyrrolidone or N, N-dimethyl acetamide.

Compared with the prior art, the invention has the beneficial effects that:

(1) the soluble polyimide containing the hexamethyl substitution structure introduces a symmetrical hexamethyl substitution structure into a polyimide main chain, improves the free volume of a polymer molecular structure space, shows better solubility and higher gas separation performance, and has potential application value in the field of membrane separation.

(2) According to the invention, the hexamethylbenzene side group is successfully introduced into the polyimide main chain by one-step solution polycondensation of the aromatic diamine monomer containing the hexamethyl substitution structure and the dianhydride monomer, the synthesis and preparation process is simple, and the industrial amplification production is easy to realize.

Drawings

FIG. 1 is a schematic representation of the diamine monomer 4, 6-bis- (2,4, 6-trimethyl-phenoxy) -1, 3-diaminobenzene of example 1¹H NMR spectrum.

FIG. 2 shows a polyimide PI prepared from diamine monomer 4, 6-bis- (2,4, 6-trimethyl-phenoxy) -1, 3-diaminobenzene and diphenyl ether tetracarboxylic dianhydride in example 1¹H NMR spectrum.

FIG. 3 is an infrared spectrum of a diamine monomer 4, 6-bis- (2,4, 6-trimethyl-phenoxy) -1, 3-diaminobenzene and a polyimide PI a prepared in example 1.

FIG. 4 shows DSC curves of 3 polyimides PI a-c prepared from diamine monomer 4, 6-bis- (2,4, 6-trimethyl-phenoxy) -1, 3-diaminobenzene and diphenyl ether tetracarboxylic dianhydride, diphenyl tetracarboxylic dianhydride, and benzophenone tetracarboxylic dianhydride, respectively.

FIG. 5 shows the reaction conditions of 3 polyimides PI a-c prepared from diamine monomer 4, 6-bis- (2,4, 6-trimethyl-phenoxy) -1, 3-diaminobenzene and diphenyl ether tetracarboxylic dianhydride, diphenyl tetracarboxylic dianhydride and benzophenone tetracarboxylic dianhydride, respectively, in N₂Thermogravimetric curve of lower.

FIG. 6 is the thermogravimetric curves of 3 polyimides PI a-c prepared from diamine monomer 4, 6-bis- (2,4, 6-trimethyl-phenoxy) -1, 3-diaminobenzene and diphenyl ether tetracarboxylic dianhydride, diphenyl tetracarboxylic dianhydride and benzophenone tetracarboxylic dianhydride respectively under air in examples.

Detailed Description

Preferred embodiments of the present invention will be described in more detail with reference to specific examples.

The following are the raw materials and drugs used in the examples:

4, 6-bis- (2,4, 6-trimethyl-phenoxy) -1, 3-diaminobenzene: the purity of the product is 99% which is prepared by a laboratory (see patent CN 111153813A for details).

Diphenyl ether tetracarboxylic dianhydride: shanghai institute for synthetic resins, purity 99%.

Biphenyl tetracarboxylic dianhydride: shanghai institute for synthetic resins, purity 99%.

Benzophenone tetracarboxylic dianhydride: shanghai institute for synthetic resins, purity 99%.

M-cresol: aladdin reagent, Inc., 99% pure.

Isoquinoline: alfa corporation, 99% pure.

N-methylpyrrolidone: jiangsu Shengqiang functional chemical company, 99 percent.

N, N-dimethylacetamide: jiangsu Shengqiang functional chemical company, 99 percent.

Example 1

The embodiment provides a preparation method of a soluble polyimide film material containing a hexamethyl substitution structure, which comprises the following steps:

(1) 1.1294g (3mmol) of diamine monomer 4, 6-bis- (2,4, 6-trimethyl-phenoxy) -1, 3-diaminobenzene and 0.9306g (3mmol) of diphenyl ether tetracarboxylic dianhydride are respectively added into a 100mL dry three-neck flask provided with a nitrogen protection and a condenser tube, then 12mL of m-cresol and 0.04mmol of isoquinoline are sequentially added, the mixture is stirred at 100 ℃ for half an hour until the monomer is completely dissolved, the mixture is continuously heated to 185 ℃ for reaction for 10 hours to obtain a viscous polymer solution, the reaction is finished, the polymer solution is poured into ethanol for sedimentation, and the fibrous polyimide polymer containing the hexamethyl substitution structure is obtained after filtration, washing and drying, wherein the yield is 99 percent and is marked as PI a. It is composed of¹H NMR(DMSO-d₆400MHz) as shown in figure 2; FT-IR (KBr) is shown in FIG. 3.

(2) Weighing 0.5g of polyimide polymer, adding 10mL of N, N-dimethylacetamide solvent to prepare a 5 wt% solution, filtering, coating, and further drying in vacuum at 80 ℃ for 15h to obtain the corresponding polyimide membrane material containing the hexamethyl substitution structure.

Example 2

The embodiment provides a preparation method of a soluble polyimide film material containing a hexamethyl substitution structure, which comprises the following steps:

(1) 1.1294g (3mmol) of diamine monomer 4, 6-bis- (2,4, 6-trimethyl-phenoxy) -1, 3-diaminobenzene and 0.8827g (3mmol) of biphenyltetracarboxylic dianhydride are respectively added into a 100mL dry three-neck flask provided with a nitrogen protection and a condenser tube, 16mL of m-cresol and 0.08mmol of isoquinoline are sequentially added into the three-neck flask, the mixture is stirred at 110 ℃ for half an hour until the monomer is completely dissolved, the mixture is continuously heated to 195 ℃ for reaction for 10 hours to obtain a viscous polymer solution, the reaction is finished, the polymer solution is poured into ethanol for sedimentation, and the fibrous polyimide polymer containing the hexamethyl substitution structure is obtained after filtration, washing and drying, wherein the yield is 99 percent and is marked as PI b.

(2) Weighing 0.5g of polyimide polymer, adding 9mL of N-methylpyrrolidone solvent to prepare a 5 wt% solution, filtering, coating, and further drying in vacuum at 80 ℃ for 15h to obtain the corresponding polyimide membrane material containing the hexamethyl substitution structure.

Example 3

The embodiment provides a preparation method of a soluble polyimide film material containing a hexamethyl substitution structure, which comprises the following steps:

(1) 1.1294g (3mmol) of diamine monomer 4, 6-bis- (2,4, 6-trimethyl-phenoxy) -1, 3-diaminobenzene and 0.9667g (3mmol) of benzophenonetetracarboxylic dianhydride are respectively added into a 100mL dry three-neck flask provided with a nitrogen protection and a condenser tube, 14mL of m-cresol and 0.08mmol of isoquinoline are sequentially added into the three-neck flask, the mixture is stirred at 110 ℃ for half an hour until the monomer is completely dissolved, the mixture is continuously heated to 195 ℃ for reaction for 10 hours to obtain a viscous polymer solution, the reaction is finished, the polymer solution is poured into ethanol for sedimentation, and the fibrous polyimide polymer containing the hexamethyl substitution structure is obtained after filtration, washing and drying, wherein the yield is 99 percent and is marked as PI c.

(2) Weighing 0.5g of polyimide polymer, adding 10mL of N, N-dimethylacetamide solvent to prepare a 5 wt% solution, filtering, coating, and further drying in vacuum at 80 ℃ for 15h to obtain the corresponding polyimide membrane material containing the hexamethyl substitution structure.

In the above examples, 3 kinds of polyimides PI a-c prepared from diamine monomer 4, 6-bis- (2,4, 6-trimethyl-phenoxy) -1, 3-diaminobenzene and diphenyl ether tetracarboxylic dianhydride, diphenyl tetracarboxylic dianhydride, and benzophenone tetracarboxylic dianhydride, respectively, have DSC curves shown in FIG. 4, where N is₂The thermal weight loss curve under the air is shown in figure 5, and the thermal weight loss curve under the air is shown in figure 6; its intrinsic viscosity in DMAc and M dissolved in DMF_w、M_nThe values and polydispersity index (PDI) are shown in Table 1, their solubility properties in Table 2, their thermodynamic properties in Table 3, and their gas separation properties in Table 4.

TABLE 1 intrinsic viscosity and molecular weight of polyimides

^aMonodisperse polystyrene was used as a standard and DMF was used as a solvent to prepare a 0.005g/mL solution for testing.

TABLE 2 solubility Properties of polyimides

+++: 100mg of polymer resin was completely dissolved in 1mL of solvent (10 wt%); ++: 50mg of polymer resin was completely dissolved in 1mL of solvent (5 wt%); +: 10mg of the polymer resin was completely dissolved in 1mL of the solvent (about 1 wt%); -: not dissolved.

TABLE 3 thermal Properties of the polyimides

^aTemperature at 10% mass loss;^bn at 800 DEG C₂Residual mass percent of polymer under atmosphere

TABLE 4 gas separation Performance of polyimides

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and technical principles of the described embodiments, and such modifications and variations should also be considered as within the scope of the present invention.