CN110105189B - Fluorine-containing polyacid monomer and preparation method thereof, polyamide and preparation method thereof, and polyamide film - Google Patents
Fluorine-containing polyacid monomer and preparation method thereof, polyamide and preparation method thereof, and polyamide film Download PDFInfo
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- CN110105189B CN110105189B CN201910423420.3A CN201910423420A CN110105189B CN 110105189 B CN110105189 B CN 110105189B CN 201910423420 A CN201910423420 A CN 201910423420A CN 110105189 B CN110105189 B CN 110105189B
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C65/00—Compounds having carboxyl groups bound to carbon atoms of six—membered aromatic rings and containing any of the groups OH, O—metal, —CHO, keto, ether, groups, groups, or groups
- C07C65/21—Compounds having carboxyl groups bound to carbon atoms of six—membered aromatic rings and containing any of the groups OH, O—metal, —CHO, keto, ether, groups, groups, or groups containing ether groups, groups, groups, or groups
- C07C65/24—Compounds having carboxyl groups bound to carbon atoms of six—membered aromatic rings and containing any of the groups OH, O—metal, —CHO, keto, ether, groups, groups, or groups containing ether groups, groups, groups, or groups polycyclic
- C07C65/26—Compounds having carboxyl groups bound to carbon atoms of six—membered aromatic rings and containing any of the groups OH, O—metal, —CHO, keto, ether, groups, groups, or groups containing ether groups, groups, groups, or groups polycyclic containing rings other than six-membered aromatic rings
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
- C08G69/42—Polyamides containing atoms other than carbon, hydrogen, oxygen, and nitrogen
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2603/00—Systems containing at least three condensed rings
- C07C2603/93—Spiro compounds
- C07C2603/94—Spiro compounds containing "free" spiro atoms
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2377/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
- C08J2377/06—Polyamides derived from polyamines and polycarboxylic acids
Abstract
The invention provides a fluorine-containing polyacid monomer and a preparation method thereof, polyamide and a preparation method thereof, and a polyamide film, and belongs to the technical field of organic synthesis. The fluorine-containing polyacid monomer provided by the invention has a spiro microporous structure, a flexible group and a large-volume trifluoromethyl structure, and the polyamide synthesized by using the fluorine-containing polyacid monomer has a microporous structure and a hyperbranched structure, so that the gas permeability of the polyamide is good; the existence of ether bond increases the free volume and flexibility of a polymer molecular chain, so that the solubility of polyamide is good; the polyamide membrane prepared by the polyamide of the invention has better gas selectivity and permeability. The invention provides a preparation method of the fluorine-containing polyacid monomer and the polyamide, which is simple and feasible, has short synthetic route and is suitable for industrial mass production.
Description
Technical Field
The invention relates to the technical field of organic synthesis, and particularly relates to a fluorine-containing polyacid monomer and a preparation method thereof, polyamide and a preparation method thereof, and a polyamide film.
Background
Gas separation membranes (GS) are mostly non-porous membranes and the gas permeation process follows a "solution-diffusion" mechanism. Aromatic polyamide has good heat resistance, mechanical strength and separation performance due to aromatic ring structure on the main chain and intermolecular hydrogen bonding, and is widely applied to the field of gas separation for 20 th century and 90 th year.
As a green separation technology, compared with separation technologies such as cryogenic separation and pressure swing adsorption separation, the separation process of the gas separation membrane technology has the advantages of high separation efficiency, simple operation, low energy consumption, greenness, no pollution and the like, is recognized as a novel gas separation technology with the most development and application prospect in the 21 st century, and is widely applied to the fields of medical food, biochemistry, energy environmental protection and the like. Compared with the traditional gas separation technology, the membrane separation has the advantages of low energy consumption, low investment, simple equipment and the like, and has important application in the aspects of oxygen/nitrogen separation, gas dehumidification, carbon dioxide recovery, hydrogen separation recovery and the like.
However, in general, the permeability and selectivity of a polymer membrane are in a mutually restrictive relationship, i.e., the selectivity decreases as the permeability increases, which is known as the Trade-off effect. Therefore, synthesizing a polymer with a microporous structure and preparing a high molecular gas separation membrane with high permeability and high selectivity has a very profound influence on improving the gas separation efficiency and expanding the application range.
Disclosure of Invention
In view of the above, the present invention aims to provide a fluorine-containing polyacid monomer and a preparation method thereof, a polyamide and a preparation method thereof, and a polyamide film. The fluorine-containing polyacid monomer provided by the invention has a spiro microporous structure, a flexible group and a large-volume trifluoromethyl structure, and polyamide synthesized by using the fluorine-containing polyacid monomer has a microporous structure and a hyperbranched structure and is good in solubility; the polyamide membrane prepared by the polyamide of the invention has better gas selectivity and permeability.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a fluorine-containing polyacid monomer, which has a structure shown in a formula I or a formula II:
the invention provides a preparation method of the fluorine-containing polyacid monomer, when the fluorine-containing polyacid monomer has a structure shown in a formula I, the preparation method comprises the following steps:
(1) under the action of a reducing agent and an acid catalyst, hexafluoroacetone and catechol are subjected to isomerization reaction to obtain spiro tetraphenol with a structure shown in a formula (a);
(2) under the action of a catalyst, carrying out substitution reaction on spiro tetraphenol with a structure shown in a formula (a) and p-fluorobenzonitrile to obtain a tetracyanospiro compound with a structure shown in a formula (b);
(3) carrying out hydrolysis reaction on a tetracyano spiro-compound with a structure shown in a formula (b) in an alkaline solvent, and then adjusting the pH value of a hydrolysis reaction liquid to be acidic to obtain a fluorine-containing polyacid monomer with a structure shown in a formula I;
when the fluorine-containing polyacid monomer has a structure shown in a formula II, the preparation method comprises the following steps:
(i) under the action of a reducing agent and an acid catalyst, carrying out isomerization reaction on hexafluoroacetone, catechol and phenol to obtain spiro triphenol with a structure shown in a formula (c);
(ii) under the action of a catalyst, carrying out substitution reaction on spiro-trisphenol with a structure shown in a formula (c) and fluorobenzonitrile to obtain a tricyano spiro-compound with a structure shown in a formula (d);
(iii) carrying out hydrolysis reaction on the tricyano spiro compound with the structure shown in the formula (d) in an alkaline solvent, and then adjusting the pH value of a hydrolysis reaction liquid to be acidic to obtain the fluorine-containing polyacid monomer with the structure shown in the formula II.
Preferably, the reducing agent in step (1) and step (i) is one or more of hydrazine hydrate, zinc powder, magnesium powder, iron powder, stannous chloride, ferrous chloride and sodium borohydride.
Preferably, the molar ratio of the hexafluoroacetone, the catechol and the reducing agent in the step (1) is 1-2: 1-2: 5-10;
in the step (i), the molar ratio of the hexafluoroacetone, the catechol, the phenol and the reducing agent is 1.5-6: 1-4: 5-10.
Preferably, the isomerization reaction temperature in the step (1) and the isomerization reaction temperature in the step (i) are independently 117-125 ℃, and the time is independently 10-12 h.
Preferably, the molar ratio of the spirocyclic tetraphenol to the p-fluorobenzonitrile in the step (2) is 1: 4-9; the catalyst is sodium hydride and/or cesium fluoride; the temperature of the substitution reaction is 150-200 ℃, and the time is 10-12 h;
the molar ratio of the spiro trisphenol to the p-fluorobenzonitrile in the step (ii) is 1: 4-9; the catalyst is sodium hydride and/or cesium fluoride; the temperature of the substitution reaction is 150-200 ℃, and the time is 10-12 h.
Preferably, the temperature of the hydrolysis reaction in the step (3) and the step (iii) is 80-100 ℃ independently, and the time is 15-20 h independently.
The invention also provides a polyamide having a structure represented by formula III:
in the formula III, one R substituent is H, and the other three R substituents are substituents with the structure shown in the formula (e); or in the formula III, four R substituents are all substituents with the structure shown in the formula (e);
in formula (e) AR is
The invention provides a preparation method of the polyamide, which comprises the following steps:
carrying out polycondensation reaction on a fluorine-containing polyacid monomer and a diamine monomer in a polar organic solvent under the action of a salt forming agent to obtain polyamide;
the fluorine-containing polyacid monomer is the fluorine-containing polyacid monomer with the structure shown in the formula I or the formula II.
The invention also provides a polyamide film which comprises the polyamide or the polyamide prepared by the method.
The invention provides a fluorine-containing polyacid monomer which has a structure shown in a formula I or a formula II. The fluorine-containing polyacid monomer provided by the invention has a spiro microporous structure, a flexible group (ether bond) and a large-volume trifluoromethyl (-CF)3) And (5) structure. The fluorine-containing polyacid monomer provided by the invention is further polymerized with a diamine monomer to obtain polyamide with a structure shown in a formula III. The polyamide provided by the invention has a microporous structure among molecules, so that small gas molecules can easily permeate; meanwhile, the polyamide provided by the invention is a hyperbranched polymer, and the existence of the hyperbranched structure enables larger gaps to exist among molecules, so that the permeability coefficient of the polyamide can be improved. In addition, the existence of ether bond in the polyamide increases the free volume and flexibility of polymer molecular chain, so that the solvent is easy to permeate, and the problem of poor solubility of the traditional gas separation membrane caused by rigid chain is solved; in addition, the existence of the large-volume trifluoromethyl increases the distortion degree of molecules and the volume of the molecules, improves the free volume of the polymer, thereby increasing the permeability of gas, and in addition, the fluorine atom in the trifluoromethyl can increase the interaction with an organic solvent due to electronegativity, thereby improving the solubility of the polymer. The results of the examples show that the polyamides provided by the invention can be used in DMAC, DMF, NMP, DMSO, THF and CHCl3Has good solubility.
The invention also provides a polyamide film which has better gas selectivity and permeability. The embodiment result shows that the permeability coefficient of the polyamide film provided by the invention to oxygen is 45-99 Barrer, the permeability coefficient to carbon dioxide is 210-395 Barrer, the gas separation coefficient to the mixed gas of carbon dioxide and nitrogen is 8.7-33.8, the gas separation coefficient to the mixed gas of carbon dioxide and methane is 7.9-18.1, and the gas separation coefficient to the mixed gas of oxygen and nitrogen is 1.9-6.3.
Drawings
FIG. 1 is a nuclear magnetic resonance hydrogen spectrum of a fluorine-containing polyacid monomer prepared in example 1 of the present invention;
FIG. 2 is an infrared spectrum of a polyamide prepared in examples 3 to 5 of the present invention.
Detailed Description
The invention provides a fluorine-containing polyacid monomer, which has a structure shown in a formula I or a formula II:
the fluorine-containing polyacid monomer provided by the invention has a spiro microporous structure, a flexible group (ether bond) and a bulky group trifluoromethyl (-CF)3) And (5) structure.
The invention provides a preparation method of the fluorine-containing polyacid monomer, when the fluorine-containing polyacid monomer has a structure shown in a formula I, the preparation method comprises the following steps:
(1) under the action of a reducing agent and an acid catalyst, hexafluoroacetone and catechol are subjected to isomerization reaction to obtain spiro tetraphenol with a structure shown in a formula (a);
(2) under the action of a catalyst, carrying out substitution reaction on spiro tetraphenol with a structure shown in a formula (a) and p-fluorobenzonitrile to obtain a tetracyanospiro compound with a structure shown in a formula (b);
(3) carrying out hydrolysis reaction on the tetracyano spiro-compound with the structure shown in the formula (b) in an alkaline solution, and then adjusting the pH value of a hydrolysis reaction solution to be acidic to obtain the fluorine-containing polyacid monomer with the structure shown in the formula I.
According to the invention, hexafluoroacetone and catechol are subjected to isomerization reaction under the action of a reducing agent and an acid catalyst to obtain the spiro tetraphenol with the structure shown in the formula (a). In the invention, the reducing agent is preferably one or more of hydrazine hydrate, zinc powder, magnesium powder, iron powder, stannous chloride, ferrous chloride and sodium borohydride; the molar ratio of the hexafluoroacetone to the catechol to the reducing agent is preferably 1-2: 1-2: 5 to 10. In the present invention, the hexafluoroacetone functions to provide a reaction environment and to provide a trifluoromethyl group, and the reducing agent functions to further convert F and O generated in the reaction into HF and H2O。
In the present invention, the acid catalyst is preferably acetic acid. In a specific embodiment of the invention, catechol and acetic acid are preferably mixed to obtain an acetic acid solution of catechol, and the dosage ratio of catechol to acetic acid is preferably 45-55 g: 1mol, more preferably 50 g: 1 mol.
The present invention also preferably adds an acidifying agent, preferably hydrogen iodide, to the isomerization reaction system. In the embodiment of the present invention, it is preferable to mix hexafluoroacetone and hydrogen iodide to obtain a hexafluoroacetone solution of hydrogen iodide; the mass concentration of hydrogen iodide in the hexafluoroacetone solution of hydrogen iodide is preferably 80-99%, and more preferably 85%.
In the isomerization reaction, it is preferable in the present invention that a hexafluoroacetone solution of hydrogen iodide and an acetic acid solution of catechol are added first, and then a reducing agent is added, followed by the isomerization reaction under heating reflux. In the invention, the temperature of the isomerization reaction is preferably 117-125 ℃, more preferably 118-122 ℃; the time of the isomerization reaction is preferably 10-12 h, and more preferably 11 h; the heating reflux is preferably carried out under a nitrogen atmosphere. In the invention, the heating reflux has the function of fully heating the system, improving the reaction progress degree and shortening the reaction progress time.
After the isomerization reaction is completed, the present invention preferably performs a post-treatment on the isomerization reaction liquid, and the post-treatment preferably includes the following steps:
and (3) sequentially cooling, carrying out hydrothermal treatment, filtering and washing the isomerization reaction liquid to obtain the spiro tetraphenol with the structure shown in the formula (a).
In the present invention, the isomerization reaction solution is preferably cooled to obtain a supersaturated solution. The present invention does not require any particular cooling means, and cooling means known to those skilled in the art may be used. In the invention, the temperature of the hydrothermal treatment is preferably 220-260 ℃, and more preferably 240-250 ℃; the time of the hydrothermal treatment is preferably 5-8 h, and more preferably 6-7 h; the pressure of the hydrothermal treatment is preferably 1MPa to 0.5GPa, and more preferably 100 MPa to 400 MPa. According to the present invention, a spiro tetraphenol having a structure represented by formula (a) can be precipitated from a reaction solution by hydrothermal treatment, and a spiro tetraphenol crystal can be obtained by filtration. According to the invention, the spirocyclic tetraphenol crystal is preferably washed, and the washing detergent is preferably glacial acetic acid and tetrahydrofuran; the crystals are preferably washed alternately with glacial acetic acid and tetrahydrofuran in the present invention, preferably 3 times.
After the spiro-tetraphenol is obtained, the spiro-tetraphenol with the structure shown in the formula (a) and p-fluorobenzonitrile are subjected to substitution reaction under the action of a catalyst to obtain the tetracyano spiro-compound with the structure shown in the formula (b). In the invention, the molar ratio of the spirocyclic tetraphenol to the p-fluorobenzonitrile is preferably 1: 4-9, and more preferably 1: 5-8. In the invention, the catalyst is preferably sodium hydride and/or cesium fluoride, and the molar ratio of the spirocyclic tetraphenol to the catalyst is preferably 1: 4-8, and more preferably 1: 5-7.
According to the invention, after the spiro tetraphenol and the p-fluorobenzonitrile are preferably mixed, the temperature is firstly raised to the substitution reaction temperature, and then the catalyst is added; the mixing mode is preferably stirring mixing, and the stirring time is preferably 0.5 h; the heating rate is preferably 10-12 ℃/min; in the invention, the temperature is preferably raised to the substitution reaction temperature by using a microwave heating mode, and the frequency of the microwave is preferably 2-3 GHz. In the invention, the substitution reaction is preferably carried out under the protection of nitrogen, and the temperature of the substitution reaction is preferably 150-200 ℃, and more preferably 160-180 ℃; the time of the substitution reaction is preferably 10-12 h, more preferably 11h, and the time of the substitution reaction is calculated from the time after the catalyst is added.
After the substitution reaction is completed, the present invention preferably subjects the substitution reaction product to a post-treatment to obtain a tetracyano spiro compound solid. In the present invention, the post-treatment preferably comprises the steps of:
discharging the reaction product into a mixed solvent, heating and refluxing, adding a poor solvent to precipitate crystals, and then sequentially carrying out solid-liquid separation, drying and recrystallization to obtain the tetracyano spiro compound solid.
In the present invention, the mixed solvent is preferably a mixed solvent of N, N-dimethylformamide and deionized water; the volume ratio of the N, N-dimethylformamide to the deionized water in the mixed solvent is preferably 1: 1. In the present invention, the poor solvent is preferably water, and the amount of the poor solvent is such that crystals are just precipitated and the precipitation of crystals does not disappear after stirring. The present invention has no particular requirement on the manner of solid-liquid separation, drying and recrystallization, and the above-described operation manner known to those skilled in the art can be used.
After the tetracyano spiro compound is obtained, the tetracyano spiro compound with the structure shown in the formula (b) is subjected to hydrolysis reaction in an alkaline solution, and then the pH value of a hydrolysis reaction solution is adjusted to be acidic, so that the fluorine-containing polyacid monomer with the structure shown in the formula I is obtained. In the invention, the alkaline solution is preferably an aqueous sodium hydroxide solution, and the mass concentration of the aqueous sodium hydroxide solution is preferably 40-50%, and more preferably 45%; the molar ratio of the tetracyano spiro-compound to the solute in the sodium hydroxide aqueous solution is preferably 1: 8.5-9.5, and more preferably 1: 8.8.
According to the invention, the tetracyano spiro compound and the alkaline solution are preferably placed in a solvent for hydrolysis reaction, the solvent is preferably a mixed solution of water and absolute ethyl alcohol, and the volume ratio of water to absolute ethyl alcohol in the mixed solution is preferably 1: 0.5-1.5, and more preferably 1: 1. In the invention, the temperature of the hydrolysis reaction is preferably 80-100 ℃, more preferably 90 ℃, and the time of the hydrolysis reaction is preferably 15-20 h, more preferably 16-18 h. In the present invention, tetracyanospirocyclic compounds are hydrolyzed under basic conditions to form carboxylic acid salts.
After the hydrolysis reaction is finished, the pH value of the hydrolysis reaction liquid is adjusted to be acidic, and a solid product is obtained. In the present invention, the pH of the hydrolysis reaction solution is preferably adjusted to 1.5 to 2.5, more preferably 2. According to the invention, ethanol in the reaction solution is preferably evaporated, the filtrate after ethanol evaporation is cooled and discharged into deionized water, and then the pH value is adjusted. In the invention, the dosage of the deionized water is preferably 400-500 mL, and more preferably 450 mL. The present invention does not require any particular regulator for adjusting pH, and any acidic pH regulator known to those skilled in the art may be used. In the present invention, adjusting the pH to acidity can convert the carboxylate group in the carboxylate salt to a carboxyl group and precipitate a solid product.
After the solid product is obtained, the invention preferably carries out suction filtration, washing and drying on the solid product in sequence to obtain the fluorine-containing polyacid monomer with the structure shown in the formula I. The present invention does not require any particular manner of suction filtration, washing and drying, and the above-described operations, which are well known to those skilled in the art, may be used.
When the fluorine-containing polyacid monomer has a structure shown in formula II, the preparation method comprises the following steps:
(i) under the action of a reducing agent and an acid catalyst, carrying out isomerization reaction on hexafluoroacetone, catechol and phenol to obtain spiro triphenol with a structure shown in a formula (c);
(ii) under the action of a catalyst, carrying out substitution reaction on spiro-trisphenol with a structure shown in a formula (c) and fluorobenzonitrile to obtain a tricyano spiro-compound with a structure shown in a formula (d);
(iii) carrying out hydrolysis reaction on the tricyano spiro compound with the structure shown in the formula (d) in an alkaline solvent, and then adjusting the pH value of a hydrolysis reaction liquid to be acidic to obtain the fluorine-containing polyacid monomer with the structure shown in the formula II.
According to the invention, hexafluoroacetone, catechol and phenol are subjected to isomerization reaction under the action of a reducing agent and an acid catalyst to obtain the spiro triphenol with the structure shown in the formula (c). In the invention, the reducing agent is preferably one or more of hydrazine hydrate, zinc powder, magnesium powder, iron powder, stannous chloride, ferrous chloride and sodium borohydride; the molar ratio of the hexafluoroacetone to the catechol to the phenol to the reducing agent is 1.5-6: 1-4: 5-10, and more preferably 2-4: 2-3: 6-9. In the present invention, the hexafluoroacetone functions to provide a reaction environment and to provide a trifluoromethyl group, and the reducing agent functions to further convert F and O generated in the reaction into HF and H2O。
In the present invention, the acid catalyst is preferably acetic acid. In the embodiment of the present invention, preferably, catechol and phenol are mixed with acetic acid, respectively, to obtain an acetic acid solution of catechol and an acetic acid solution of phenol; the mass concentration of the catechol in the acetic acid solution of the catechol is preferably 10-55%, and more preferably 20-50%; the mass concentration of phenol in the acetic acid solution of phenol is preferably 10-55%, and more preferably 20-50%.
The present invention also preferably adds an acidifying agent, preferably hydrogen iodide, to the isomerization reaction system. In the specific embodiment of the invention, hexafluoroacetone and hydrogen iodide are mixed to obtain a hexafluoroacetone solution of hydrogen iodide; the mass concentration of hydrogen iodide in the hexafluoroacetone solution of hydrogen iodide is preferably 80-99%, and more preferably 85%. In the present invention, the hydrogen iodide functions as an acidifying agent, and can increase the reaction rate.
In the isomerization reaction, it is preferable in the present invention that a hexafluoroacetone solution of hydrogen iodide, an acetic acid solution of catechol, an acetic acid solution of phenol and a reducing agent are added, and then the isomerization reaction is carried out under heating reflux. In the invention, the temperature of the isomerization reaction is preferably 117-125 ℃, more preferably 118-122 ℃; the time of the isomerization reaction is preferably 10-12 h, and more preferably 11 h; the heating reflux is preferably carried out under a nitrogen atmosphere. In the invention, the heating reflux has the function of fully heating the system, improving the reaction progress degree and shortening the reaction progress time.
After the isomerization reaction is completed, the present invention preferably performs a post-treatment on the isomerization reaction liquid, and the post-treatment preferably includes the following steps:
and (3) sequentially cooling, carrying out hydrothermal treatment, filtering and washing the isomerization reaction liquid to obtain the spiro trisphenol with the structure shown in the formula (c).
In the present invention, the isomerization reaction solution is preferably cooled to obtain a supersaturated solution. The present invention does not require any particular cooling means, and cooling means known to those skilled in the art may be used. In the invention, the temperature of the hydrothermal treatment is preferably 220-260 ℃, and more preferably 240-250 ℃; the time of the hydrothermal treatment is preferably 5-8 h, and more preferably 6-7 h; the pressure of the hydrothermal treatment is preferably 1MPa to 0.5GPa, and more preferably 100 MPa to 400 MPa. According to the invention, the spiro triphenol with the structure shown in the formula (c) can be precipitated from the reaction solution through hydrothermal treatment, and the spiro triphenol crystal can be obtained through filtration. According to the invention, the spirocyclic triphenol crystal is preferably washed, and the washing detergent is preferably glacial acetic acid and tetrahydrofuran; the crystals are preferably washed alternately with glacial acetic acid and tetrahydrofuran in the present invention, preferably 3 times.
After the spiro-trisphenol is obtained, the spiro-trisphenol with the structure shown in the formula (c) and the fluorobenzonitrile are subjected to substitution reaction under the action of a catalyst to obtain the tricyano-spiro-compound with the structure shown in the formula (d). In the invention, the molar ratio of the spirocyclic trisphenol to the p-fluorobenzonitrile is preferably 1: 4-9, and more preferably 1: 5-8. In the invention, the catalyst is preferably sodium hydride and/or cesium fluoride, and the molar ratio of the spirocyclic trisphenol to the catalyst is preferably 1: 4-8, and more preferably 1: 5-7.
According to the invention, after the spiro trisphenol and the p-fluorobenzonitrile are preferably mixed, the temperature is firstly raised to the substitution reaction temperature, and then the catalyst is added; the mixing mode is preferably stirring mixing, and the stirring time is preferably 0.5 h; the heating rate is preferably 10-12 ℃/min; in the invention, the temperature is preferably raised to the substitution reaction temperature by using a microwave heating mode, and the frequency of the microwave is preferably 2-3 GHz. In the invention, the substitution reaction is preferably carried out under the protection of nitrogen, and the temperature of the substitution reaction is preferably 150-200 ℃, and more preferably 160-180 ℃; the time of the substitution reaction is preferably 10-12 h, more preferably 11h, and the time of the substitution reaction is calculated from the time after the catalyst is added.
After the substitution reaction is completed, the present invention preferably performs a post-treatment of the substitution reaction product to obtain a tricyanospiral compound solid. In the present invention, the post-treatment preferably comprises the steps of:
discharging the reaction product into a mixed solvent, heating and refluxing, adding a poor solvent to precipitate crystals, and then sequentially carrying out solid-liquid separation, drying and recrystallization to obtain the tricyano spiro compound solid.
In the present invention, the mixed solvent is preferably a mixed solvent of N, N-dimethylformamide and deionized water; the volume ratio of the N, N-dimethylformamide to the deionized water in the mixed solvent is preferably 1: 1. In the present invention, the poor solvent is preferably water, and the amount of the poor solvent is such that crystals are just precipitated and the precipitation of crystals does not disappear after stirring. The present invention has no particular requirement on the manner of solid-liquid separation, drying and recrystallization, and the above-described operation manner known to those skilled in the art can be used.
After the tricyano spiro compound is obtained, the tricyano spiro compound with the structure shown in the formula (d) is subjected to hydrolysis reaction in an alkaline solution, and then the pH value is adjusted to be acidic, so that the fluorine-containing polyacid monomer with the structure shown in the formula II is obtained. In the invention, the alkaline solution is preferably an aqueous sodium hydroxide solution, and the mass concentration of the aqueous sodium hydroxide solution is preferably 40-50%, and more preferably 45%; the molar ratio of the tricyano spiro compound to the solute in the sodium hydroxide aqueous solution is preferably 1: 6-8, and more preferably 1: 6.6. In the invention, the tricyano spiro compound and the alkaline solution are placed in a solvent for hydrolysis reaction, the solvent is preferably a mixed solution of water and absolute ethyl alcohol, and the volume ratio of water to absolute ethyl alcohol in the mixed solution is preferably 1: 0.5-1.5, and more preferably 1: 1. In the invention, the temperature of the hydrolysis reaction is preferably 80-100 ℃, more preferably 90 ℃, and the time of the hydrolysis reaction is preferably 15-20 h, more preferably 16-18 h. In the present invention, the tricyano spiro compound is hydrolyzed under basic conditions to produce a carboxylate.
After the hydrolysis reaction is finished, the pH value of the hydrolysis reaction liquid is adjusted to be acidic, and a solid product is obtained. In the present invention, the pH of the hydrolysis reaction solution is preferably adjusted to 1.5 to 2.5, more preferably 2. According to the invention, ethanol in the reaction solution is preferably evaporated, the filtrate after ethanol evaporation is cooled and discharged into deionized water, and then the pH value is adjusted. In the invention, the dosage of the deionized water is preferably 400-500 mL, and more preferably 450 mL. The present invention does not require any particular regulator for adjusting pH, and any acidic pH regulator known to those skilled in the art may be used. In the present invention, adjusting the pH to acidity can convert the carboxylate group in the carboxylate salt to a carboxyl group and precipitate a solid product.
After the solid product is obtained, the invention preferably carries out suction filtration, washing and drying on the solid product in sequence to obtain the fluorine-containing polyacid monomer with the structure shown in the formula II. The present invention does not require any particular manner of suction filtration, washing and drying, and the above-described operations, which are well known to those skilled in the art, may be used.
The invention provides polyamide, which has a structure shown in a formula III:
in the formula III, one R substituent is H, and the other three R substituents are substituents with the structure shown in the formula (e), or four R substituents in the formula III are all substituents with the structure shown in the formula (e);
in formula (e) AR is
In the present invention, the structure represented by formula III is a repeating structural unit of polyamide.
The polyamide provided by the invention has a microporous structure among molecules, so that small gas molecules can easily permeate; meanwhile, the polyamide provided by the invention is a hyperbranched polymer, and the existence of the hyperbranched structure enables larger gaps to exist among molecules, so that the permeability coefficient of the polyamide can be improved. In addition, the existence of ether bond in the polyamide increases the free volume and flexibility of polymer molecular chain, so that the solvent is easy to permeate, and the problem of poor solubility of the traditional gas separation membrane caused by rigid chain is solved; in addition, the existence of the large-volume trifluoromethyl increases the distortion degree of molecules and the volume of the molecules, improves the free volume of the polymer, thereby increasing the permeability of gas, and in addition, the fluorine atom in the trifluoromethyl can increase the interaction with an organic solvent due to electronegativity, thereby improving the solubility of the polymer.
The invention provides a preparation method of the polyamide, which comprises the following steps: carrying out polycondensation reaction on a fluorine-containing polyacid monomer and a diamine monomer in a polar organic solvent under the action of a salt forming agent to obtain polyamide;
the fluorine-containing polyacid monomer is the fluorine-containing polyacid monomer with the structure shown in the formula I or the formula II.
In the invention, when the fluorine-containing polyacid monomer has a structure shown in formula I, all four R substituents in formula III are substituents having a structure shown in formula (e); when the fluorine-containing polyacid monomer has a structure shown in a formula II, one R substituent in the formula III is H, and the other three R substituents are substituents having a structure shown in a formula (e).
In the invention, the salt forming agent is preferably one or more of potassium carbonate, cesium carbonate and sodium carbonate, and the structure of the diamine monomer is preferably as follows: h2N-AR-NH2Wherein AR is
In the invention, under the protection of nitrogen, diamine monomer and fluorine-containing polyacid monomer are subjected to polycondensation reaction in a polar organic solvent to obtain polyamide. In the present invention, the molar ratio of the fluorine-containing polyacid monomer, the diamine monomer and the salt-forming agent is preferably 1: 2-4: 2 to 2.5, more preferably 1: 3: 2.25; in the present invention, the polar organic solvent preferably includes N, N '-dimethylformamide or N, N' -dimethylacetamide; the mass ratio of the sum of the mass of the fluorine-containing polyacid monomer, the salt forming agent and the diamine monomer to the organic solvent is preferably 15-20: 100, more preferably 16 to 18: 100. in the invention, the temperature of the polycondensation reaction is preferably 0-25 ℃, more preferably 20-25 ℃, and the time is preferably 3-24 hours, more preferably 5-20 hours. The invention obtains viscous polyamide through polycondensation reaction.
After the polycondensation reaction is completed, the polycondensation reaction liquid is preferably sequentially cooled, washed and dried to obtain the polyamide. The present invention does not require any particular cooling means, such as natural cooling, which is well known to those skilled in the art. The invention obtains viscous polyamide through cooling treatment. In the invention, the washing detergent is preferably deionized water and ethanol; the invention preferably uses alternate washing of deionized water and ethanol, the number of the alternate washing is preferably 3, wherein the deionized water washing can remove the salt forming agent and the ethanol washing can remove the residual organic solvent. In the present invention, the drying is preferably performed under reduced pressure; the drying temperature is preferably 100 ℃ and the drying time is preferably 12 h.
The invention also provides a polyamide film which comprises the polyamide in the technical scheme or the polyamide prepared by the method.
In the present invention, the thickness of the polyamide film is preferably 60 to 70 μm, and more preferably 64 to 68 μm. The polyamide film provided by the invention has better gas selectivity and permeability.
In the present invention, the method for preparing the polyamide film preferably comprises the steps of:
dissolving the polyamide in an N, N-dimethylacetamide solvent to obtain a polyamide solution;
and coating the polyamide solution on the surface of a substrate, and sequentially carrying out temperature programming and cooling to obtain the polyamide film.
The polyamide is dissolved in an N, N-dimethylacetamide solvent to obtain a polyamide solution. In the present invention, the mass of the polyamide is preferably 10 to 20% of the mass of the solvent, and more preferably 15%.
After the polyamide solution is obtained, the polyamide solution is coated on the surface of a substrate, and then the polyamide film is obtained by sequentially carrying out temperature programming and cooling. The invention has no special requirements on the coating mode, and the coating mode known by the technicians in the field can be used; the present invention does not require any particular material for the substrate, and a substrate for preparing a thin film, which is well known to those skilled in the art, may be used.
In the invention, the programmed temperature rise preferably comprises four stages, namely a first stage, a second stage, a third stage and a fourth stage; the temperature of the first stage is preferably 60-80 ℃, and the time is preferably 4-5 h; the temperature of the two stages is preferably 80-100 ℃, more preferably 90 ℃, and the time is preferably 12-14 h; the temperature of the three stages is preferably 110-130 ℃, more preferably 120 ℃, and the time is preferably 4-5 h; the temperature of the four stages is preferably 140-160 ℃, more preferably 150 ℃, and the time is preferably 4-5 h. In the present invention, the cooling method is preferably natural cooling.
The following examples are provided to illustrate the fluorinated polyacid monomer and the preparation method thereof, the polyamide and the preparation method thereof, and the polyamide film in detail, but they should not be construed as limiting the scope of the present invention.
Example 1
85g of 99% by mass HI aqueous solution was added to 15mL of hexafluoroacetone to form a mixed solution, and the formed mixed solution was added to 170g of catechol-containing acetic acid aqueous solution having a mass concentration of 48.6 g/mol. Then 4.2g of hydrazine hydrate is dripped into the solution, the obtained solution is heated and refluxed for 10h at 120 ℃, then cooled to room temperature to obtain a supersaturated solution, the obtained supersaturated solution is used for separating out a white microcrystalline compound by a hydrothermal crystallization method at 240 ℃ and 0.3GPa, the white microcrystalline compound is filtered, and the white microcrystalline compound is washed three times by glacial acetic acid and dichloromethane alternately to obtain 13.0908g of the spirocyclic tetraphenol compound.
Adding 8.3445g (15mmol) of prepared spiro tetraphenol, 7.7510g (64mmol) of p-fluorobenzonitrile and 12mL of N-methylpyrrolidone into a 250mL three-neck flask with a mechanical stirring device, stirring until the raw materials are completely dissolved, stirring at room temperature for half an hour under the protection of nitrogen, heating to 150 ℃ by adopting 2GHz microwave at the heating rate of 10 ℃/min, adding 9.6640g (64mmol) of cesium fluoride, reacting for 10 hours, and stopping the reaction when TLC detects that the raw material point disappears; after the reaction is finished, the system is discharged into a mixed system with the volume ratio of N, N-dimethylformamide to deionized water being 1:1, the system is heated to the reflux temperature, poor solvent deionized water is added until precipitation just occurs, and the mixture is stirred and does not disappear to obtain 8.2616g of tetracyano spiro tetraphenol compound.
The structure of the product of the tetracyano spiro tetraphenol compound prepared by the invention is as shown in formula (b):
adding 8.2616g (8mmol) of tetracyanospiro compound into a 250mL three-neck flask provided with a mechanical stirring device, adding 68mL of a mixed reaction system with a volume ratio of deionized water to absolute ethyl alcohol of 1:1 and a sodium hydroxide aqueous solution (containing 70.4 mmol) with a mass concentration of 45%, heating the system to 90 ℃ at a heating rate of 20 ℃/min by using microwaves with the frequency of 3GHz and the output power of 900W as an energy source, reacting for 20h by TLC, evaporating the ethanol, collecting filtrate, cooling the filtrate, placing the filtrate in deionized water, adjusting the pH value to 2 until white substances are separated out, collecting the precipitates, carrying out suction filtration, washing a filter cake to be neutral by using the deionized water, and carrying out vacuum drying on the product for 12h at 100 ℃ to obtain 5.5435g of the fluorine-containing polyacid monomer.
The structure of the fluorine-containing polyacid monomer obtained in example 1 is shown as formula I:
example 2
5g of an aqueous solution of HI having a mass content of 99% was added to 10mL of hexafluoroacetone to form a mixed solution, and the formed mixed solution was added to 100mL of an acetic acid solution containing 11.5165g (105mmol) of catechol and 14.1165g (150mmol) of phenol at the same time, and then 3.6g of hydrazine hydrate was slowly dropped into the solution. Stirring, heating and refluxing for 15h under the protection of nitrogen gas, cooling to room temperature to obtain supersaturated solution, separating out white microcrystalline compound at 240 deg.C and 0.5GPa from the supersaturated solution by hydrothermal crystallization, filtering, and alternately washing with glacial acetic acid and tetrahydrofuran for three times to obtain spiro trisphenol compound.
15mmol of spiro trisphenol compound, 64mmol of p-fluorobenzonitrile and 11mL of N-methylpyrrolidone are added into a 250mL three-neck flask provided with a mechanical stirring device, the mixture is stirred until the raw materials are completely dissolved, the temperature is raised to 150 ℃ by adopting a microwave with the frequency of 150GHz at the temperature rise rate of 10 ℃/min under the protection of nitrogen, and 105mmol of cesium fluoride catalyst is added. Detecting by TLC until the raw material point disappears, namely ending the reaction, and stopping the reaction; and (3) discharging the system after the reaction is finished in a mixed system with the volume ratio of N, N-dimethylformamide to deionized water being 1:1, heating the system to the reflux temperature, adding poor solvent deionized water until precipitation is just carried out, stirring and the precipitation does not disappear to obtain 7.3247g of tricyano spiro compound, wherein the structure of the tricyano spiro compound is as shown in formula (d):
adding 7.3247g (8mmol) of tricyano spiro compound into a 250mL three-neck flask with a mechanical stirring device, adding 68mL of a mixed reaction system with a volume ratio of deionized water to absolute ethyl alcohol of 1:1 and a sodium hydroxide aqueous solution (containing 70.4 mmol) with a mass concentration of 45%, heating the system to 90 ℃ at a heating rate of 20 ℃/min by using a microwave with a frequency of 3GHz and an output power of 900W as an energy source, reacting for 20h by using the system, evaporating the ethyl alcohol after TLC (thin layer chromatography) detection until a raw material point disappears, collecting filtrate, cooling the filtrate, placing the filtrate in deionized water, adjusting the pH value to 2 until white matter is separated out, collecting the precipitate, performing suction filtration, washing a filter cake by using deionized water to be neutral, and performing vacuum drying on the product at 100 ℃ for 12h to obtain 4.8629g of a fluorine-containing polyacid monomer, wherein the structure of the fluorine-containing polyacid monomer is as shown in formula:
example 3
In a 50mL three-necked flask provided with a nitrogen inlet and outlet, a magnetic stirrer, a thermometer and a condenser, under the protection of nitrogen, 2mmol of the spirotetramic acid compound prepared in example 1 and 13mL of N, N-dimethylacetamide are added to ensure that the solid content of the system is 15%, 4mmol of potassium carbonate is slowly added after the solid content is completely dissolved, the mixture reacts for 3h at room temperature, 5mmol of phenylenediamine is added, the mixture reacts for 20h at 200 ℃ under the protection of nitrogen, then the temperature is slowly increased to 265 ℃, the mixture is further polycondensed for 2h, polyamide is obtained after natural cooling, the obtained viscous polyamide is alternately washed for three times by adopting deionization and ethanol to fully remove residual salt forming agent and solvent, the pressure is reduced at 100 ℃ for 12h to obtain 2.8981g of dry resin, the dry resin is marked as PA-1, and the obtained product has the structure as:
example 4
Adding 2mmol of the spiro-tetracid compound prepared in example 1 and 13mL of N, N-dimethylacetamide into a 50mL three-necked flask provided with a nitrogen inlet and outlet, a magnetic stirrer, a thermometer and a condenser under the protection of nitrogen, slowly adding 4mmol of potassium carbonate after the spiro-tetracid compound and the N, N-dimethylacetamide are completely dissolved, reacting for 2 hours at room temperature, adding 6mmol of benzidine, reacting for 15 hours at 200 ℃ under the protection of nitrogen, slowly heating to 300 ℃, further performing polycondensation for 2 hours, naturally cooling to obtain polyamide, washing the obtained viscous polyamide three times by adopting deionization and ethanol alternately, fully removing residual salt forming agent and solvent, decompressing for 12 hours at 100 ℃ to obtain 3.4764g of dry resin which is marked as PA-2, wherein the obtained product has the structure as shown in formula (2):
example 5
Adding 2mmol of the spiro-tetracid compound prepared in example 1 and 13mL of N, N-dimethylacetamide into a 50mL three-necked flask provided with a nitrogen inlet and outlet, a magnetic stirrer, a thermometer and a condenser under the protection of nitrogen, slowly adding 4mmol of potassium carbonate after the spiro-tetracid compound and the N, N-dimethylacetamide are completely dissolved, reacting for 2.5h at room temperature, adding 7mmol of diaminodiphenyl ether, reacting for 18h at 200 ℃ under the protection of nitrogen, then heating to 280 ℃, further slowly polycondensing for 2h, naturally cooling to obtain polyamide, washing the obtained viscous polyamide three times by adopting deionization and ethanol alternately, fully removing residual salt forming agent and solvent, decompressing for 12h at 100 ℃ to obtain 3.5980g of dried resin marked as PA-3, wherein the obtained product has the structure as shown in formula (3):
example 6
Adding 2mmol of the spiro-tetracid compound prepared in example 1 and 13mL of N, N-dimethylacetamide in a 50mL three-necked flask provided with a nitrogen inlet and outlet, a magnetic stirrer, a thermometer and a condenser under the protection of nitrogen, slowly adding 4mmol of potassium carbonate after all the spiro-tetracid compound and 13mL of N, N-dimethylacetamide are dissolved, reacting for 3 hours at room temperature, adding 8mmol of 4, 4' -diaminobenzophenone, reacting for 20 hours at 200 ℃ under the protection of nitrogen, then slowly heating to 300 ℃, further polycondensing for 2 hours, naturally cooling to obtain polyamide, washing the obtained viscous polyamide three times by adopting deionization and ethanol alternately, fully removing residual salt forming agent and solvent, decompressing for 12 hours at 100 ℃ to obtain 3.6893g of dried resin marked as PA-4, wherein the obtained product has the structure as shown in formula (4):
example 7
Adding 2mmol of the spiro triacid compound prepared in example 2 and 13mL of N, N-dimethylacetamide into a 50mL three-necked flask provided with a nitrogen inlet and outlet, a magnetic stirrer, a thermometer and a condenser under the protection of nitrogen, slowly adding 4mmol of potassium carbonate after the spiro triacid compound and the N, N-dimethylacetamide are completely dissolved, reacting for 2h at room temperature, adding 5mmol of phenylenediamine, reacting for 20h at 200 ℃ under the protection of nitrogen, slowly heating to 265 ℃, further polycondensing for 2h, naturally cooling to obtain polyamide, washing the obtained viscous polyamide three times by adopting deionization and ethanol alternately, fully removing residual salt forming agent and solvent, decompressing for 12h at 100 ℃ to obtain 2.4416g of dry resin which is marked as PA-5, wherein the obtained product has the structure as shown in formula (5):
example 8
In a 50mL three-necked flask provided with a nitrogen inlet and outlet, a magnetic stirrer, a thermometer and a condenser, under the protection of nitrogen, 2mmol of the spiro triacid compound prepared in example 2 and 13mL of N, N-dimethylacetamide are added, after the spiro triacid compound and the N, N-dimethylacetamide are completely dissolved, 4mmol of potassium carbonate are slowly added to react for 2h at room temperature, 6mmol of benzidine is added to react for 20h at 200 ℃ under the protection of nitrogen, then the temperature is slowly increased to 300 ℃, the polycondensation is further carried out for 2h, the polyamide is obtained by natural cooling, the obtained viscous polyamide is alternately washed for three times by deionization and ethanol, the residual salt former and solvent are fully removed, the pressure is reduced for 12h at 100 ℃, 2.8754g of dry resin is obtained, the label is PA-6, and the obtained product has the structure shown in formula (:
example 9
Adding 2mmol of the spiro triacid compound prepared in the example 2 and 13mL of N, N-dimethylacetamide into a 50mL three-necked flask provided with a nitrogen inlet and outlet, a magnetic stirrer, a thermometer and a condenser under the protection of nitrogen, slowly adding 4mmol of potassium carbonate after the spiro triacid compound and the N, N-dimethylacetamide are completely dissolved, reacting for 3h at room temperature, adding 4mmol of diaminodiphenyl ether, reacting for 20h at 200 ℃ under the protection of nitrogen, slowly heating to 265 ℃, further polycondensing for 2h, naturally cooling to obtain polyamide, washing the obtained viscous polyamide three times by adopting deionization and ethanol alternately, fully removing residual salt forming agent and solvent, decompressing for 12h at 100 ℃ to obtain 2.9665g of dry resin which is marked as PA-7, wherein the obtained product has the structure as shown in formula (7):
example 10
Adding 2mmol of the spiro triacid compound prepared in the example 2 and 13mL of N, N-dimethylacetamide in a 50mL three-necked flask provided with a nitrogen inlet and outlet, a magnetic stirrer, a thermometer and a condenser under the protection of nitrogen, slowly adding 4mmol of potassium carbonate after the spiro triacid compound and the N, N-dimethylacetamide are completely dissolved, reacting for 3h at room temperature, adding 6mmol of 4, 4' -diaminobenzophenone, reacting for 20h at 200 ℃ under the protection of nitrogen, then slowly heating to 300 ℃, further polycondensing for 2h, naturally cooling to obtain polyamide, washing the obtained viscous polyamide three times by adopting deionization and ethanol alternately, fully removing residual salt forming agent and solvent, decompressing for 12h at 100 ℃ to obtain 3.0349g of dry resin marked as PA-8, wherein the obtained product has the structure as shown in formula (8):
structural characterization
The fluorine-containing polyacid monomer prepared in example 1 was subjected to a hydrogen nuclear magnetic resonance spectroscopy test, and the test results are shown in fig. 1, and it can be seen from fig. 1 that the fluorine-containing polyacid monomer prepared in the present invention has a structure consistent with the expected structure.
The fluorine-containing polyacid monomer prepared in example 2 was subjected to a nuclear magnetic resonance hydrogen spectroscopy test, and the test results showed that the fluorine-containing polyacid monomer prepared in the present invention had a structure consistent with expectations.
The polyamide prepared in examples 3-5 was subjected to an infrared test, and the test results are shown in fig. 2, and it can be seen from fig. 2 that the polyamide prepared by the present invention has a structure consistent with the expectation.
The polyamide prepared in the embodiment 6-10 is subjected to infrared test, and the test result shows that the polyamide prepared by the method has a structure consistent with the expectation.
Performance testing
1. Solubility test
The solubility of the polyamides prepared in examples 3-10 was tested by the following method: the polyamide was dissolved in DMAC, DMF, NMP, DMSO, THF and CHCl, respectively3The concentration of polyamide in the different solvents was 10 mg/mL. Testing the solubility of polyamide in different solvents, wherein, + + represents room temperature total solubility; + represents heating to dissolve completely; -represents partial dissolution; - - -means insoluble by heating. The test results are shown in table 1.
TABLE 1 solubility of polyamides obtained in examples 3 to 10
| Solvent/sample | PA-1 | PA-2 | PA-3 | PA-4 | PA-5 | PA-6 | PA-7 | PA-8 |
| DMAC | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ |
| DMF | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ |
| NMP | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ |
| DMSO | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ |
| THF | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ |
| CHCl3 | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ |
As can be seen from the test results in Table 1, the polyamide prepared by using the fluorine-containing polyacid monomer provided by the invention has better solubility. The fluorine-containing polyacid monomer provided by the invention introduces groups such as an aliphatic structure, ether bonds, trifluoromethyl and the like, so that the obtained polyamide has good solubility in most polar solvents.
2. Gas separation test
The polyamides obtained in the embodiments 3-10 of the present invention were prepared into polyamide films, which were numbered ①, ②, ③, ④, ⑤, ⑥, ⑦, and ⑧, respectively.
The preparation method comprises the following steps:
dissolving polyamide in N, N-dimethylacetamide at a solid content of 15%, filtering through a 0.45-micron Teflon filter to remove insoluble substances to obtain a uniform polyamide solution, uniformly coating the solution on a clean 9cm × 9cm glass plate, placing the glass plate in an oven, raising the temperature by adopting a program, treating the glass plate sequentially at 60 ℃/4h, 90 ℃/12h, 120 ℃/4h and 150 ℃/4h, and naturally cooling to obtain the transparent polyamide film.
The gas separation test was performed on ① - ⑧ polyamide films, and the test results are shown in table 2, and the test methods were:
the method comprises the steps of sealing a test film in a test tank by using epoxy resin, setting the upstream pressure to be 2atm, vacuumizing the downstream, testing at 35 ℃ after the downstream pressure is stabilized for a period of time, representing the separation effect of the polymer film on gas by using a gas permeability coefficient, and representing the selectivity of ideal gas, wherein the gas separation coefficient is calculated by αA/B＝PA/PB，PAAnd PBThe permeability coefficients of the two gases A and B are respectively.
Gas separation Performance of Polyamide films Nos. 2 ① to ⑧ in Table 2
As can be seen from Table 2, the polyamide film prepared from the polyamide provided by the invention has good gas separation performance, and has a permeability coefficient for nitrogen of 8-45 Barrer, a permeability coefficient for methane of 15-50 Barrer, a permeability coefficient for oxygen of 45-99 Barrer and a permeability coefficient for carbon dioxide of 210-395 Barrer. Therefore, the polyamide film prepared from the polyamide provided by the invention has higher permeability to gas.
The polyamide film provided by the invention has a gas separation coefficient of 8.7-33.8 for a mixed gas of carbon dioxide and nitrogen, a gas separation coefficient of 7.9-18.1 for a mixed gas of carbon dioxide and methane, and a gas separation coefficient of 1.9-6.3 for a mixed gas of oxygen and nitrogen. Therefore, the polyamide film prepared from the polyamide provided by the invention has high selectivity to gas, namely, after the polyamide film is prepared from the polyamide provided by the invention, the polyamide film has the characteristic of high permeability while good selectivity is ensured.
In conclusion, the polyamide prepared from the fluorine-containing polyacid monomer provided by the invention is prepared by adding DMAC, DMF, NMP, DMSO, THF and CHCl3The polyamide membrane prepared from the polyamide has better solubility, and has better gas selectivity and permeability when being used for gas separation.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (9)
1. A fluorine-containing polyacid monomer, having a structure represented by formula I or formula II:
2. the method for producing a fluorinated polyacid monomer of claim 1, wherein when the fluorinated polyacid monomer has the structure of formula I, the method comprises the steps of:
(1) under the action of a reducing agent and an acid catalyst, hexafluoroacetone and catechol are subjected to isomerization reaction to obtain spiro tetraphenol with a structure shown in a formula (a);
(2) under the action of a catalyst, carrying out substitution reaction on spiro tetraphenol with a structure shown in a formula (a) and p-fluorobenzonitrile to obtain a tetracyanospiro compound with a structure shown in a formula (b);
(3) carrying out hydrolysis reaction on a tetracyano spiro-compound with a structure shown in a formula (b) in an alkaline solvent, and then adjusting the pH value of a hydrolysis reaction liquid to be acidic to obtain a fluorine-containing polyacid monomer with a structure shown in a formula I;
when the fluorine-containing polyacid monomer has a structure shown in a formula II, the preparation method comprises the following steps:
(i) under the action of a reducing agent and an acid catalyst, carrying out isomerization reaction on hexafluoroacetone, catechol and phenol to obtain spiro triphenol with a structure shown in a formula (c);
(ii) under the action of a catalyst, carrying out substitution reaction on spiro-trisphenol with a structure shown in a formula (c) and fluorobenzonitrile to obtain a tricyano spiro-compound with a structure shown in a formula (d);
(iii) carrying out hydrolysis reaction on a tricyano spiro-compound with a structure shown in a formula (d) in an alkaline solvent, and then adjusting the pH value of a hydrolysis reaction liquid to be acidic to obtain a fluorine-containing polyacid monomer with a structure shown in a formula II;
the reducing agent in the step (1) and the reducing agent in the step (i) are independently one or more of hydrazine hydrate, zinc powder, magnesium powder, iron powder, stannous chloride, ferrous chloride and sodium borohydride; the acid catalyst is acetic acid; hexafluoroacetone is a hexafluoroacetone solution in which hexafluoroacetone and hydrogen iodide are mixed to obtain hydrogen iodide.
3. The preparation method according to claim 2, wherein the molar ratio of the hexafluoroacetone, the catechol and the reducing agent in the step (1) is 1-2: 1-2: 5-10;
in the step (i), the molar ratio of the hexafluoroacetone, the catechol, the phenol and the reducing agent is 1.5-6: 1-4: 5-10.
4. The method according to claim 2, wherein the isomerization reaction in step (1) and step (i) is carried out at a temperature of 117 to 125 ℃ for 10 to 12 hours.
5. The preparation method according to claim 2, wherein the molar ratio of the spirocyclic tetraphenol to the p-fluorobenzonitrile in the step (2) is 1: 4-9; the catalyst is sodium hydride and/or cesium fluoride; the temperature of the substitution reaction is 150-200 ℃, and the time is 10-12 h.
The molar ratio of the spiro trisphenol to the p-fluorobenzonitrile in the step (ii) is 1: 4-9; the catalyst is sodium hydride and/or cesium fluoride; the temperature of the substitution reaction is 150-200 ℃, and the time is 10-12 h.
6. The preparation method according to claim 2, wherein the hydrolysis reaction in the step (3) and the step (iii) independently has a temperature of 80 to 100 ℃ and a time of 15 to 20 hours.
7. A polyamide having a structure represented by formula III:
in the formula III, one R substituent is H, and the other three R substituents are substituents with the structure shown in the formula (e); or in the formula III, four R substituents are all substituents with the structure shown in the formula (e);
in formula (e) AR is
8. A process for producing a polyamide as claimed in claim 7, which comprises the steps of:
carrying out polycondensation reaction on a fluorine-containing polyacid monomer and a diamine monomer in a polar organic solvent under the action of a salt forming agent to obtain polyamide;
the fluorine-containing polyacid monomer is the fluorine-containing polyacid monomer of claim 1 or the fluorine-containing polyacid monomer obtained by the method of any one of claims 2 to 6.
9. A polyamide film comprising the polyamide according to claim 7 or the polyamide produced by the method according to claim 8.
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