Polyamide synthesized by carbon dioxide and preparation method thereof

Abstract

The invention relates to polyamide synthesized by carbon dioxide and a preparation method thereof, and belongs to the technical field of polymer synthesis. The technical problems of long reaction time, low yield, poor product performance and the like in the existing technology for converting the carbon dioxide into the polymer by utilizing the Ugi multi-component reaction are solved. The preparation method comprises the following steps: in a halogenated hydrocarbon solvent, pre-polymerizing primary diamine and aryl dialdehyde, adding alcohols, an organic base catalyst, CO2 and mono-functional group isonitrile, reacting to obtain a reactant, and purifying the reactant to obtain polyamide. The preparation method is mild in reaction condition, short in reaction time and high in yield, the use of di-isonitrile is avoided, the cost can be reduced, and the prepared polyamide has excellent solvent resistance, is only slowly dissolved in dichloromethane and trichloromethane and is insoluble in other solvents.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer synthesis, and specifically relates to a polyamide synthesized with the participation of carbon dioxide and a preparation method thereof, that is, using a bio-based platform compound and carbon dioxide as raw materials to synthesize a polyamide with a completely new structure and a preparation method thereof. Background Art

[0002] Carbon dioxide is a trace gas in the earth's atmosphere and plays an important role in the carbon cycle. However, due to the burning of fossil fuels and deforestation, the carbon balance is destroyed, and the excess carbon dioxide in the atmosphere is one of the causes of global warming. So far, there are only a few examples of industrial production using carbon dioxide as a raw material, such as the synthesis of methanol, urea or salicylic acid. In the field of polymer synthesis, polycarbonate can be obtained by copolymerizing epoxides and carbon dioxide in the presence of aluminum, chromium, cobalt or zinc complexes. However, this method requires a complex catalyst and is difficult to achieve industrialization.

[0003] Polyamide is a polymer containing repeated amide groups -NHCO- on the main chain of the molecule. In nature, it often exists in the form of polypeptides or proteins in organisms. There are many varieties of artificially synthesized polyamides. Due to their good comprehensive properties, including mechanical properties, heat resistance, wear resistance and chemical resistance, they are widely used. There are basically two existing polyamide polymerization technologies. One is to produce it by condensation reaction of diamines and dibasic acids, and the other is to produce it by condensation or ring-opening polymerization of ω-amino acids or cyclic lactams. Since the synthesized polyamide has a high melting point (170-260°C), both synthetic routes require very high polymerization temperatures, and depending on the process routes, high pressure or vacuum conditions are usually required.

[0004] The Ugi reaction is a classic organic synthesis reaction for synthesizing α-amidoamides using four components: one molecule of aldehyde or ketone, one molecule of amine, one molecule of isonitrile, and one molecule of carboxylic acid. It was first reported in 1959. The Ugi reaction has mild conditions, high atom economy, and only one molecule of water is produced as a byproduct during the entire process. It has been widely used in synthetic chemistry, drug synthesis, and life sciences.

[0005] Keating et al.'s paper: The Ugi five-component condensation using CO2, CS2, and COS as oxidized carbon sources (Journal of Organic Chemistry, 1998, 63(3): 867-871. DOI: 10.1021 / jo971463z) shows that carbon dioxide can activate alcohols, and the in situ generated carbonate anions can act as the acid component (i.e., nucleophile) in the typical Ugi reaction, and undergo acylation reaction with the imine group. The intramolecular acyl transfer is functionally irreversible and provides a certain driving force for the reaction, ultimately incorporating CO2 as a carbon source into the synthesized compounds. However, this study only completed the synthesis of small molecule compounds and did not involve the field of polymer synthesis.

[0006] Sehlinger et al.'s paper: Diversely substituted polyamides: macromolecular design using the Ugi four-component reaction (Macromolecules, 2014, 47(9): 2774-2783. DOI: 10.1021 / ma500504w) first explored the application of the Ugi multi-component reaction in the field of polymer synthesis, that is, the use of bifunctional 1,6-hexanediamine and 2,7-dimethyloctanedial, monofunctional hexanoic acid and tert-butyl isonitrile to synthesize N-substituted polyamides. However, this paper only improved the Ugi reaction raw materials to be bifunctional, and did not use CO2 for the reaction.

[0007] Sehlinger et al.'s paper: Ugi reactions with CO2: access to functionalized polyurethanes, polycarbonates, polyamides, and polyhydantoins (Macromolecular Rapid Communications, 2014, 35 (21): 1866-71. DOI: 10.1002 / marc.201400385) further utilized the Ugi polymerization reaction system, CO2 and methanol as acid components, and used a one-time addition method to successfully synthesize polyamide using 1,12-diaminododecane, isobutyraldehyde, 1,6-hexanediisocyanate, CO2 and methanol. However, the reaction time was too long, reaching 72 hours; the yield was also low, with a maximum of only 56%; and the raw material 1,6-hexanediisocyanate was expensive and difficult to synthesize. The product polyamide had poor solvent resistance and a low glass transition temperature, making it difficult to apply on a large scale in industry.

[0008] In summary, the existing technologies for converting carbon dioxide into polymers using Ugi multi-component reactions have some shortcomings, such as long reaction time, low yield and poor product performance, and there is still broad room for development. Starting from cheap, readily available and green and sustainable raw materials, there is no report on the method of synthesizing polyamide using bio-based platform compounds and their derivatives. Summary of the invention

[0009] In view of the problems existing in the prior art, the present invention provides a polyamide synthesized by the participation of carbon dioxide and a preparation method thereof, that is, using 2,5-diformylfuran, a derivative of a bio-based platform compound, and CO2 as raw materials, through Ugi multi-component reaction, a polyamide with special physical and chemical characteristics is synthesized. The diamine and dialdehyde are prepolymerized by batch feeding to obtain an imine intermediate to increase the degree of polymerization of the product; and then a small amount of organic base catalyst is added to shorten the reaction time and increase the yield.

[0010] The present invention adopts the following technical solutions to solve the above technical problems:

[0011] The present invention provides a polyamide synthesized with the participation of carbon dioxide, the structural formula of which is shown in Formula 1:

[0012]

[0013] In the formula, R1 is a C2-C20 alkyl chain, a molecular chain containing an aromatic group or a molecular chain containing an ether bond, R2 is a molecular chain containing an aromatic group, and R3 is an alkyl group, an alkenyl group, an alkynyl group or an aryl group;

[0014] The number average molecular weight of the polyamide is 6000 to 12000 g mol -1 The glass transition temperature is between 85 and 95°C.

[0015] More preferably, the structural formula of the polyamide is one of the following structures:

[0016]

[0017] The present invention also provides a method for preparing the polyamide synthesized with the participation of carbon dioxide, the steps of which are as follows:

[0018] In a halogenated hydrocarbon solvent, a primary diamine and an aromatic dialdehyde are first prepolymerized, and then alcohols, an organic base catalyst, CO2 and a monofunctional isonitrile are added to react to obtain a reactant, and the reactant is purified to obtain a polyamide;

[0019] The primary diamine is an alkyl diamine, an aromatic diamine or an ether diamine.

[0020] Preferably, the halogenated hydrocarbon solvent is dichloromethane (DCM) and the alcohol is methanol (MeOH); more preferably, the volume ratio of dichloromethane to methanol is 1:1.

[0021] Preferably, the primary diamine is 1,5-diaminopentane, 1,6-diaminohexane, 1,10-diaminodecane or polyetheramine.

[0022] Preferably, the aromatic dialdehyde includes one of 2,5-diformylfuran and terephthalaldehyde.

[0023] Preferably, the monofunctional isonitrile includes one of tert-butylacetonitrile and isocyanomethane.

[0024] Preferably, the concentration of the primary diamine in the halogenated hydrocarbon solvent is 0.1-0.2 mmol / mL. To ensure an equimolar reaction, the amount of the aromatic dialdehyde is the same as the amount of the primary diamine, and the amount of the monofunctional isonitrile is at least twice the amount of the primary diamine.

[0025] More preferably, the molar ratio of the primary diamine, the aromatic dialdehyde and the monofunctional isonitrile is 1:1:2.2 to 1:1:3.

[0026] Preferably, the organic base catalyst is triethylamine.

[0027] Preferably, the amount of the organic base catalyst is 1-10% of the amount of the alcohol substance; more preferably, the amount of the organic base catalyst is 5% of the amount of the alcohol substance.

[0028] Preferably, the pressure of the carbon dioxide is 0.5-1.5 MPa; more preferably, the pressure of the carbon dioxide is 1 MPa.

[0029] Preferably, the prepolymerization time is at least 0.5 h, and the prepolymerization temperature is 0-30° C.; more preferably, the prepolymerization time is 2 h.

[0030] Preferably, the reaction time is 6 to 16 hours, and the reaction temperature is 0 to 30°C; more preferably, the reaction time is 12 hours, and the reaction temperature is 25°C.

[0031] Preferably, the method for preparing polyamide after the reactants are purified is: the reactants are first added dropwise to water with a volume of five times or more for precipitation, dissolved in chloroform after centrifugation, and then added dropwise to excess hexane for precipitation, and then the precipitate is dissolved in chloroform again and precipitated in excess hexane, and the process is repeated three times to finally obtain a yellow solid, which is dried in a vacuum drying oven to obtain the desired polyamide product.

[0032] Preferably, the drying temperature is 60° C. and the drying time is 8 hours.

[0033] The principle of the present invention is that CO2 can activate alcohols (methanol), carbonate anions generated in situ can act as nucleophiles to play the role of acid components, and organic base catalysts can activate hydroxyl groups in alcohols (methanol), thereby increasing the formation of carbonate anions. According to the Ugi classical reaction mechanism, diamine and dialdehyde pre-react to generate polyimine prepolymers, but it is known that they precipitate in methane solution and cannot continue to react. Therefore, prepolymerization should be carried out in dichloromethane first to obtain good solubility, and then excess monofunctional isonitrile, alcohols, organic base catalysts and CO2 are added, and then two nucleophilic additions, Mumm rearrangements and acyl transfer reactions are carried out to finally form a reaction product. The structure of the reaction product is confirmed by nuclear magnetic hydrogen spectrum to be the desired polyamide product.

[0034] The synthetic route of polyamide of the present invention is as follows:

[0035]

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The polyamide prepared by the invention has special physical and chemical properties, such as excellent solvent resistance, only slowly dissolving in dichloromethane and chloroform, and insoluble in other solvents, and the product glass transition temperature is between 85 and 95°C.

[0038] The preparation method of the polyamide of the present invention has mild reaction conditions and avoids the use of diisonitrile, thereby reducing costs.

[0039] The preparation method of the polyamide of the present invention comprises prepolymerizing diamine and dialdehyde by batch feeding to increase the polymerization degree of the product, and the molecular weight can reach 10000 g mol -1 Then, a small amount of organic base catalyst is added to shorten the reaction time and increase the yield to 68%.

[0040] The preparation method of the polyamide of the present invention provides a new way for carbon dioxide conversion, and large-scale application is expected to reduce carbon dioxide pollution; another raw material dialdehyde is a bio-based platform compound derivative 2,5-diformylfuran, which can be converted through microbial fermentation or chemical reaction of biomass including trees, crop straw, corn and fructose, etc., which can reduce dependence on petroleum-based raw materials and conform to the concept of green chemistry; the peptide-like structure of the product makes it biocompatible, and it can have broad application prospects in biodegradable materials, biomedical materials and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 is the hydrogen nuclear magnetic resonance spectrum of the target product of Example 1 of the present invention;

[0043] Figure 2 This is a size exclusion chromatography (SEC) image of the target product of Example 1 of the present invention;

[0044] Figure 3 is the hydrogen nuclear magnetic resonance spectrum of the target product of Example 2 of the present invention;

[0045] Figure 4 This is the size exclusion chromatography (SEC) image of the target product of Example 2 of the present invention. DETAILED DESCRIPTION

[0046] In order to further understand the present invention, preferred embodiments of the present invention are described below. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0047] In order to realize the green development of polymer materials, explore new ways of CO2 conversion, and improve the shortcomings of previous technologies, the present invention has been studied and found that a polyamide with a new structure having special physical and chemical characteristics can be synthesized by using bio-based platform compounds and CO2 as raw materials and utilizing Ugi multi-component reactions. The preparation method of the present invention can greatly reduce the polymerization reaction time and improve the product yield.

[0048] The polyamide synthesized with the participation of carbon dioxide in the present invention has a structural formula as shown in Formula 1:

[0049]

[0050] In the formula, R1 is a C2-C20 alkyl chain, a molecular chain containing an aromatic group or a molecular chain containing an ether bond, R2 is a molecular chain containing an aromatic group, and R3 is an alkyl group, an alkenyl group, an alkynyl group or an aryl group.

[0051] The number average molecular weight of the polyamide is between 6000 and 12000 g mol -1 The glass transition temperature is between 85 and 95°C. It has special physical and chemical characteristics and excellent solvent resistance. Except for slowly dissolving in a small amount of halogenated alkanes such as dichloromethane and chloroform, it is difficult to dissolve in other solvents.

[0052] In the present invention, the structural formula of the preferred polyamide is one of the following structures:

[0053]

[0054]

[0055] In formula 5, there are no special restrictions on the two n, as long as the number average molecular weight of the polyamide is between 6000 and 12000 g mol -1 The glass transition temperature can be between 85 and 95°C.

[0056] The method for preparing polyamide synthesized by carbon dioxide of the present invention comprises the following steps:

[0057] In a halogenated hydrocarbon solvent, a primary diamine and an aromatic dialdehyde are prepolymerized, and then alcohols, an organic base catalyst, CO2 and a monofunctional isonitrile are added to react to obtain a reactant, and the reactant is purified to obtain a polyamide.

[0058] In the above technical solution, the primary diamine is an alkyl diamine, an aromatic diamine or an ether diamine, such as 1,5-diaminopentane, 1,6-diaminohexane, 1,10-diaminodecane or a polyetheramine.

[0059] In the above technical scheme, in order to avoid side reactions, the aldehyde component must have a closed α-position so that it has a lower α-CH acidity to reduce the occurrence of α-CH deprotonation, so aromatic dialdehydes such as 2,5-diformylfuran or terephthalaldehyde have good effects.

[0060] In the above technical scheme, the monofunctional isonitrile is, for example, tert-butyl isonitrile, isocyanomethane and the like.

[0061] In the above technical solution, the concentration of the primary diamine in the halogenated hydrocarbon solvent is 0.1-0.2 mmol / mL, and to ensure an equimolar reaction, the amount of the aromatic dialdehyde is the same as the amount of the primary diamine, and the amount of the monofunctional isonitrile is at least twice the amount of the primary diamine. Preferably, the molar ratio of the primary diamine, the aromatic dialdehyde and the monofunctional isonitrile is 1:1:2.2-1:1:3.

[0062] In the above technical solution, the halogenated hydrocarbon solvent can improve the solubility of the imine intermediate product. If a non-halogenated hydrocarbon solvent is used, no polymer can be obtained. Alcohols are used as both reaction solvents and reactants. The halogenated hydrocarbon solvent is preferably dichloromethane (DCM), and the alcohol is preferably methanol (MeOH), and the volume ratio of the two is preferably 1:1.

[0063] In the above technical scheme, the feed is added twice, that is, the diamine and dialdehyde are prepolymerized to generate a linear imine molecular chain, and then an organic base catalyst, alcohols, CO2 and isonitrile are added for polymerization. If the one-time feeding method is adopted, due to the poor solubility of the final product, it will precipitate from the reaction solvent when the oligomer is generated, and a high molecular weight polymer cannot be obtained. The prepolymerization time is at least 0.5h, and the upper limit of the reaction time is preferably 2h. Too long prepolymerization time cannot improve the reaction yield and polymerization degree, and the effect cannot be achieved if the time is short. The prepolymerization temperature is 0-30°C, preferably 25°C. The reaction time is 6-16h, and the reaction temperature is 0-30°C; the preferred reaction time is 12h, and the reaction temperature is 25°C. When the time is further extended, the yield will not be further improved.

[0064] In the above technical solution, the organic base catalyst is triethylamine, and the amount of the organic base catalyst is 1-10% of the amount of the alcohol substance, preferably 5%.

[0065] In the above technical solution, the pressure of carbon dioxide is 0.5-1.5 MPa, preferably 1 MPa.

[0066] In the above technical scheme, the method for preparing polyamide after the reactants are purified includes precipitation separation and vacuum drying: the reactants are first dripped dropwise into water more than five times the amount for precipitation to remove methanol and small molecules, dissolved in chloroform after centrifugation, and then dripped into excess hexane for precipitation, and then the precipitate is dissolved in chloroform again and precipitated in excess hexane, and the process is repeated three times to finally obtain a yellow solid, which is dried in a vacuum drying oven at 60°C for 8 hours to obtain the desired polyamide product.

[0067] The terms used in the present invention generally have the meanings commonly understood by those of ordinary skill in the art, unless otherwise specified.

[0068] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with embodiments.

[0069] In the following examples, various processes and methods not described in detail are conventional methods known in the art. Unless otherwise specified, the materials, reagents, devices, instruments, equipment, etc. used in the following examples can be obtained from commercial sources.

[0070] Example 1

[0071] A 25mL high-pressure reactor was used, and the amount of decanediamine added was calculated according to the concentration of 0.2mmol / mL in the total DCM / MeoH mixed solution. 1mmol of decanediamine, 1mmol of 2,5-diformylfuran and 2.5mL of dichloromethane were added, and the mixture was stirred at 25°C for 2h. Then, 2.5mL of methanol, 2.2mmol of tert-butyl isonitrile, 5mol% of triethylamine (0.44mL) and 1.5MPa of CO2 were added, and the reaction was continued at 25°C for 10h with stirring. After the reaction was completed, the obtained reaction product was first dropwise added into five times more water (excess) for precipitation to remove methanol and small molecules, and then centrifuged and dissolved in chloroform, and then dropwise added into excess hexane for precipitation, and then the precipitate was dissolved again in chloroform and precipitated in excess hexane, and repeated three times to finally obtain a yellow solid, which was dried in a vacuum drying oven at 60°C for 8h to obtain the target product with a yield of 68%. The H NMR spectrum and size exclusion chromatography images of the target product are shown in Figure 1 and Figure 2 shown. 1 H NMR (CDCl3, 300MHz): δ (ppm) = 0.98-1.74 (m, 16H, 8CH2), 1.27 (s, 18H, Cq-CH3), 2.30-2.56 (m, 2H, CH2-N), 3.00- 3.33(m,2H,CH2-N),3.49-3.66(s,6H,2OCH3),6.82(m,2H,CH),6.55-7.04(m,2H,CArH),8.07-8.20(m,2H,NH); T g =95℃; M n =11600,PDI=1.95.

[0072] Comparative Example 1

[0073] A 25mL autoclave was used, and the amount of decanediamine added was calculated according to the concentration of 0.2mmol / mL in the total DCM / MeoH mixed solution. 1mmol of decanediamine, 1mmol of 2,5-diformylfuran and 2.5mL of dichloromethane were added, and the mixture was stirred at 25°C for 2h, and then 2.5mL of methanol, 2.2mmol of tert-butyl isonitrile and 1.5MPa of CO2 were added, and the mixture was stirred and reacted for 72h at 25°C. After the reaction was completed, the obtained mixture was first dripped into more than five times of water (excess) to precipitate to remove methanol and small molecules, and then centrifuged and dissolved in chloroform, and then dripped into excess hexane for precipitation, and then the precipitate was dissolved in chloroform again and precipitated in excess hexane, and repeated three times, and finally a yellow solid was obtained, which was dried at 60°C for 8h in a vacuum drying oven to obtain the target product with a yield of 38%. 1HNMR (CDCl3, 300MHz): δ (ppm) = 0.98-1.74 (m, 16H, 8CH2), 1.27 (s, 18H, Cq-CH3), 2.30-2.56 (m, 2H, CH2-N), 3.00- 3.33(m,2H,CH2-N),3.49-3.66(s,6H,2OCH3),6.82(m,2H,CH),6.55-7.04(m,2H,CArH),8.07-8.20(m,2H,NH); T g =95℃; M n =11600, PDI =1.95. The number average molecular weight, polydispersity coefficient, yield and glass transition temperature of the target product were tested, and the results are shown in Table 1.

[0074] Comparative Example 2

[0075] A 25 mL autoclave was used, and the amount of decanediamine added was calculated based on the concentration in the solution being 0.2 mmol / mL. 1 mmol of decanediamine, 1 mmol of 2,5-diformylfuran and 5 mL of methanol were added, and the mixture was stirred at 25°C for 2 h, and then 2.2 mmol of tert-butyl isonitrile, 5 mol% of triethylamine (0.44 mL) and 1.5 MPa of CO2 were added, and the mixture was stirred and reacted for 10 h at 25°C. After the reaction was completed, the resulting mixture was dripped dropwise into five times more water (excess), and no precipitation was produced.

[0076] It can be seen from Comparative Example 2 that high polymer cannot be obtained without using halogenated hydrocarbon solvent.

[0077] Comparative Example 3

[0078] A 25 mL autoclave was used, and the amount of diamine added was calculated according to the concentration of 0.2 mmol / mL in the total DCM / MeoH mixed solution. 1 mmol of decanediamine, 1 mmol of 2,5-diformylfuran, 2.2 mmol of tert-butyl isonitrile, 2.5 mL of methanol, 5 mol% of triethylamine (0.44 mL) and 2.5 mL of dichloromethane were added, and then 1.5 MPa of CO2 was charged, and the reaction was stirred at 25°C for 12 hours. After the reaction was completed, the resulting mixture was first dripped dropwise into more than five times of water (excess) to precipitate to remove methanol and small molecular substances, and then centrifuged and dissolved with chloroform, and then dripped into excess hexane. At this time, no precipitate could be obtained, indicating that no high molecular weight polymer was produced.

[0079] It can be seen from Comparative Example 3 that if the one-time addition method is adopted, the intermediate product will precipitate out from the reaction solvent when the oligomer is generated due to its poor solubility, and a high molecular weight polymer cannot be obtained.

[0080] Example 2

[0081] A 25 mL autoclave was used, and the amount of pentamethylenediamine added was calculated according to the concentration of 0.2 mmol / mL in the total DCM / MeoH mixed solution. 1 mmol of pentamethylenediamine, 1 mmol of 2,5-diformylfuran and 2.5 mL of dichloromethane were added, and the mixture was stirred at 25°C for 2 h. Then, 2.5 mL of methanol, 2.2 mmol of tert-butyl isonitrile, 5 mol% of triethylamine (0.44 mL) and 1.5 MPa of CO2 were added, and the mixture was stirred and reacted for 10 h at 25°C. After the reaction was completed, the obtained reaction product was first dripped into water (excess) more than five times to precipitate to remove methanol and small molecules, centrifuged and dissolved in chloroform, and then dripped into excess hexane for precipitation, and then the precipitate was dissolved in chloroform again and precipitated in excess hexane, and repeated three times to finally obtain a yellow solid, which was dried at 60°C in a vacuum drying oven for 8 h to obtain the target product with a yield of 66%. The H NMR spectrum and size exclusion chromatography images of the target product are shown in Figure 3 and Figure 4 shown. 1 H NMR (CDCl3, 300MHz): δ (ppm) = 0.95-1.84 (m, 6H, 3CH2), 1.33 (s, 18H, Cq-CH3), 2.20-2.74 (m, 2H, CH2-N), 3.00-3 .30(m,2H,CH2-N),3.40-3.67(s,6H,2OCH3),6.82(m,2H,CH),6.55-7.10(m,2H,CArH),8.00-8.20(m,2H,NH); T g =88℃; M n =7600,PDI=1.89.

[0082] Example 3

[0083] A 25 mL autoclave was used, and the amount of decanediamine added was calculated according to the concentration of 0.2 mmol / mL in the total DCM / MeoH mixed solution. 1 mmol of decanediamine, 1 mmol of 2,5-diformylfuran and 2.5 mL of dichloromethane were added, and the mixture was stirred at 25°C for 2 h, and then 2.5 mL of methanol, 2.2 mmol of tert-butyl isonitrile, 5 mol% of triethylamine (0.44 mL) and 1.5 MPa of CO2 were added, and the mixture was stirred and reacted for 12 h at 25°C. After the reaction was completed, the obtained reaction product was first dripped into more than five times of water (excess) to precipitate to remove methanol and small molecules, and then centrifuged and dissolved in chloroform, and then dripped into excess hexane for precipitation, and then the precipitate was dissolved in chloroform again and precipitated in excess hexane, and repeated three times, and finally a yellow solid was obtained, which was dried at 60°C in a vacuum drying oven for 8 h to obtain the target product. The number average molecular weight, polydispersity coefficient, yield and glass transition temperature of the target product were tested, and the results are shown in Table 1.

[0084] Example 4

[0085] A 25mL autoclave was used, and the amount of decanediamine added was calculated according to the concentration of 0.2mmol / mL in the total DCM / MeoH mixed solution. 1mmol of decanediamine, 1mmol of 2,5-diformylfuran and 2.5mL of dichloromethane were added, and the mixture was stirred at 25°C for 2h, and then 2.5mL of methanol, 2.2mmol of tert-butyl isonitrile, 10mol% of triethylamine (0.88mL) and 1.5MPa of CO2 were added, and the mixture was stirred and reacted for 12h at 25°C. After the reaction was completed, the obtained reaction product was first dripped into more than five times of water (excess) to precipitate to remove methanol and small molecules, centrifuged and dissolved in chloroform, and then dripped into excess hexane for precipitation, and then the precipitate was dissolved again in chloroform and precipitated in excess hexane, and repeated three times to finally obtain a yellow solid, which was dried at 60°C in a vacuum drying oven for 8h to obtain the target product. The number average molecular weight, polydispersity coefficient, yield and glass transition temperature of the target product were tested, and the results are shown in Table 1.

[0086] Example 5

[0087] A 25mL autoclave was used, and the amount of decanediamine added was calculated according to the concentration of 0.2mmol / mL in the total DCM / MeoH mixed solution. 1mmol of decanediamine, 1mmol of 2,5-diformylfuran and 2.5mL of dichloromethane were added, and the mixture was stirred at 25°C for 2h, and then 2.5mL of methanol, 2.2mmol of tert-butyl isonitrile, 5mol% of triethylamine (0.44mL) and 1.5MPa of CO2 were added, and the mixture was stirred and reacted for 6h at 25°C. After the reaction was completed, the obtained reaction product was first dripped into more than five times of water (excess) to precipitate to remove methanol and small molecules, and then centrifuged and dissolved in chloroform, and then dripped into excess hexane for precipitation, and then the precipitate was dissolved in chloroform again and precipitated in excess hexane, and repeated three times, and finally a yellow solid was obtained, which was dried at 60°C in a vacuum drying oven for 8h to obtain the target product. The number average molecular weight, polydispersity coefficient, yield and glass transition temperature of the target product were tested, and the results are shown in Table 1.

[0088] Example 6

[0089] A 25 mL autoclave was used, and the amount of decanediamine added was calculated according to the concentration of 0.2 mmol / mL in the total DCM / MeoH mixed solution. 1 mmol of decanediamine, 1 mmol of 2,5-diformylfuran and 2.5 mL of dichloromethane were added, and the mixture was stirred at 25°C for 2 h, and then 2.5 mL of methanol, 2.2 mmol of tert-butyl isonitrile, 5 mol% of triethylamine (0.44 mL) and 1.5 MPa of CO2 were added, and the mixture was stirred and reacted for 16 h at 25°C. After the reaction was completed, the obtained reaction product was first dripped into more than five times of water (excess) to precipitate to remove methanol and small molecules, and then centrifuged and dissolved in chloroform, and then dripped into excess hexane for precipitation, and then the precipitate was dissolved in chloroform again and precipitated in excess hexane, and repeated three times, and finally a yellow solid was obtained, which was dried at 60°C in a vacuum drying oven for 8 h to obtain the target product. The number average molecular weight, polydispersity coefficient, yield and glass transition temperature of the target product were tested, and the results are shown in Table 1.

[0090] Example 7

[0091] A 25mL autoclave was used, and the amount of decanediamine added was calculated according to the concentration of 0.1mmol / mL in the total DCM / MeoH mixed solution. 0.5mmol of decanediamine, 0.5mmol of 2,5-diformylfuran and 2.5mL of dichloromethane were added, and the mixture was stirred at 25°C for 2h, and then 2.5mL of methanol, 1.1mmol of tert-butyl isonitrile, 5mol% of triethylamine (0.44mL) and 1.5MPa of CO2 were added, and the mixture was stirred and reacted for 12h at 25°C. After the reaction was completed, the obtained reaction product was first dripped into more than five times of water (excess) to precipitate to remove methanol and small molecules, and then centrifuged and dissolved in chloroform, and then dripped into excess hexane for precipitation, and then the precipitate was dissolved in chloroform again and precipitated in excess hexane, and repeated three times, and finally a yellow solid was obtained, which was dried at 60°C in a vacuum drying oven for 8h to obtain the target product. The number average molecular weight, polydispersity coefficient, yield and glass transition temperature of the target product were tested, and the results are shown in Table 1.

[0092] Example 8

[0093] A 25 mL autoclave was used, and the amount of pentamethylenediamine added was calculated according to the concentration of 0.2 mmol / mL in the total DCM / MeoH mixed solution. 1 mmol of pentamethylenediamine, 1 mmol of 2,5-diformylfuran and 2.5 mL of dichloromethane were added, and the mixture was stirred at 25°C for 2 h. Then, 2.5 mL of methanol, 2.2 mmol of tert-butyl isonitrile, 5 mol% of triethylamine (0.44 mL) and 1.5 MPa of CO2 were added, and the mixture was stirred and reacted for 12 h at 25°C. After the reaction was completed, the obtained reaction product was first dripped into water (excess) of more than five times to precipitate to remove methanol and small molecules, centrifuged and dissolved in chloroform, and then dripped into excess hexane for precipitation, and then the precipitate was dissolved in chloroform again and precipitated in excess hexane, and repeated three times to finally obtain a yellow solid, which was dried at 60°C in a vacuum drying oven for 8 h to obtain the target product. The number average molecular weight, polydispersity coefficient, yield and glass transition temperature of the target product were tested, and the results are shown in Table 1.

[0094] Table 1 Effect of different reaction conditions on the present invention

[0095]

[0096]

[0097] It can be seen from Table 1 that the preparation method of the present invention has a reaction time of 6 to 16 hours, preferably 12 hours. When the time is further extended, the yield will not be further improved.

[0098] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the embodiments. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. Polyamide, characterized in that The structural formula is shown in Formula 1: In the formula, R1 is a C2-C20 alkyl chain, a molecular chain containing an aromatic group, or a molecular chain containing an ether bond, R2 is a molecular chain containing an aromatic group, and R3 is an alkyl group, an alkenyl group, an alkynyl group, or an aryl group; The number average molecular weight of the polyamide is 6000 to 12000 g mol -1 The glass transition temperature is between 85 and 95°C.

2. The polyamide according to claim 1, characterized in that The structural formula is one of the following structures:

3. The method for preparing polyamide according to claim 1 or 2, characterized in that: Here are the steps: In a halogenated hydrocarbon solvent, a primary diamine and an aromatic dialdehyde are first prepolymerized, and then alcohols, an organic base catalyst, CO2 and a monofunctional isonitrile are added to react to obtain a reactant, and the reactant is purified to obtain a polyamide; The primary diamine is an alkyl diamine, an aromatic diamine or an ether diamine.

4. The method for preparing polyamide according to claim 3, characterized in that: The primary diamine includes one of 1,5-diaminopentane, 1,6-diaminohexane, 1,10-diaminodecane and polyetheramine; And / or, the aromatic dialdehyde includes one of 2,5-diformylfuran and terephthalaldehyde; And / or, the monofunctional isonitrile includes one of tert-butylacetonitrile and isocyanomethane; And / or, the halogenated hydrocarbon solvent is dichloromethane, the alcohol is methanol, and the volume ratio of dichloromethane to methanol is 1:2 to 2:

1.

5. The method for preparing polyamide according to claim 3, characterized in that: The concentration of the primary diamine in the mixed solution of dichloromethane and alcohol is 0.1-0.2 mmol / mL, the amount of the aromatic dialdehyde is the same as that of the primary diamine, and the amount of the monofunctional isonitrile is at least twice that of the primary diamine.

6. The method for preparing polyamide according to claim 5, characterized in that: The molar ratio of the primary diamine, the aromatic dialdehyde and the monofunctional isonitrile is 1:1:2.2 to 1:1:

3.

7. The method for preparing polyamide according to claim 3, characterized in that: The organic base catalyst is triethylamine; the amount of the organic base catalyst is 1-10% of the amount of the alcohol substance.

8. The method for preparing polyamide according to claim 3, characterized in that: The pressure of the carbon dioxide is 0.5-1.5 MPa.

9. The method for preparing polyamide according to claim 3, characterized in that: The prepolymerization time is at least 0.5h, the prepolymerization temperature is 0-30°C, the reaction time is 6-16h, and the reaction temperature is 0-30°C.

10. The method for preparing polyamide according to claim 3, characterized in that: The method for preparing polyamide after the reactant is purified is: firstly, the reactant is added dropwise into water with a volume of five times or more for precipitation, centrifuged, dissolved in chloroform, then dropwise added into excess hexane for precipitation, then the precipitate is dissolved in chloroform again and precipitated in excess hexane, the process is repeated three times, and finally a yellow solid is obtained, which is dried in a vacuum drying oven to obtain the desired polyamide product.

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