Bio-based polyimide as well as preparation method and application thereof

Abstract

The invention provides bio-based polyimide as well as a preparation method and application thereof, and belongs to the technical field of polyimide. The preparation method comprises the following steps: adding a dianhydride monomer containing tetrahydrocurcumin and a diamine monomer containing tetrahydrocurcumin into a polar aprotic solvent, heating to a first temperature for reaction, then heating to a second temperature for reaction, cooling to room temperature, pouring the system into ethanol, filtering, precipitating ethanol Soxhlet extraction, and drying to obtain the bio-based polyimide. The bio-based polyimide material prepared in the invention has good flexibility, gas permeability, light transmittance, solvent resistance and corrosion resistance, not only has good mechanical properties, electrical properties and high and low temperature resistance, but also has good antibacterial and antioxidant effects, high biocompatibility and wide application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of polyimides, and in particular to a bio-based polyimide and a preparation method and application thereof. Background Art

[0002] Polyimide (PI) has been widely developed and applied in a variety of fields, including engineering plastics, electronics and electrical engineering, aerospace, and biomedicine, due to its excellent high and low temperature tolerance, high mechanical strength, good electrical properties, low thermal expansion coefficient and thermal shrinkage, suitable permeability, and low biotoxicity. Common PIs are prepared by polycondensation of aromatic diamines and dianhydrides, and their mechanical and thermal properties compare favorably to those of conventional polymers. With the rapid adoption of 5G and information technology, demand for PI materials for high-end applications such as flexible displays, thermal insulation films for space applications, and photosensitive materials for microelectronics is increasing. In particular, the development of bio-based flexible intelligent fluorescent substrates with superior overall performance will greatly expand the material options available in the flexible display field. However, existing polyimide monomers are derived from non-renewable fossil fuels, which contradicts the concept of sustainable development. Furthermore, long-term exposure to petroleum-based aromatic diamines can lead to a significantly higher incidence of malignant tumors such as bladder cancer. Consequently, researchers worldwide have recently conducted extensive research into the preparation of bio-based polyimides.

[0003] In recent years, researchers have synthesized bio-based PI using fumaric acid, 2,5-furandicarboxylic acid, 4-aminocinnamic acid, isosorbide, lignin derivatives, adenine, inositol, and soy isoflavones. However, due to conflicts between structural design and performance requirements, existing bio-based PI materials struggle to simultaneously achieve mechanical strength, heat resistance, transparency, yellowness, and biocompatibility. Furthermore, the monomer preparation routes for existing bio-based PI materials, particularly the bio-based dianhydride monomers, all utilize phthalimide substitution. This substitution requires strong alkaline hydrolysis followed by dehydration and cyclization, resulting in a cumbersome preparation process and low product yield and purity. Furthermore, hydrolysis of phthalimide substitutions in high-temperature alkaline solutions can easily cause the product to yellow.

[0004] Bio-based polyimide is made from renewable biomass resources as a monomer raw material. Compared with petroleum-based polyimide made from petroleum-based raw materials, it is environmentally friendly and has zero emissions. Therefore, the development of high-performance bio-based polyimide will have broad application prospects. Summary of the Invention

[0005] The present invention aims to provide a bio-based polyimide, a preparation method, and applications thereof. The alkyl chain of the curcumin skeleton makes the prepared bio-based polyimide material have excellent flexibility and processability. The polycyclic structure improves the gas permeability and light transmittance of the material, and has good solvent resistance and corrosion resistance. The bio-based material makes it highly biocompatible and has broad application prospects.

[0006] The technical solution of the present invention is achieved as follows:

[0007] The present invention provides a bio-based polyimide having a structure shown in the following formula:

[0008]

[0009] Wherein, n=10-1000.

[0010] The present invention further provides a method for preparing the above-mentioned bio-based polyimide, comprising the following steps: adding a dianhydride monomer containing tetrahydrocurcumin and a diamine monomer containing tetrahydrocurcumin to a polar aprotic solvent, heating to a first temperature for reaction, then heating to a second temperature for reaction, cooling to room temperature, pouring the system into ethanol, filtering, precipitating the ethanol, performing Soxhlet extraction, and drying to obtain the bio-based polyimide;

[0011] Wherein, the structural formula of the dianhydride monomer containing tetrahydrocurcumin is as shown in Formula I or Formula II:

[0012]

[0013] The structural formula of the diamine monomer containing tetrahydrocurcumin is shown in Formula III or Formula IV:

[0014]

[0015] As a further improvement of the present invention, the polar aprotic solvent is at least one of m-cresol, N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and dimethyl sulfoxide.

[0016] As a further improvement of the present invention, the molar ratio of the dianhydride monomer containing tetrahydrocurcumin to the diamine monomer containing tetrahydrocurcumin is 0.9-1.1:0.9-1.1.

[0017] As a further improvement of the present invention, the temperature of the first temperature reaction is 70-80°C and the time is 3-5 hours, the temperature of the second temperature reaction is 170-180°C and the time is 15-17 hours, and the time of the ethanol Soxhlet extraction is 5-7 hours.

[0018] As a further improvement of the present invention, the preparation method of the dianhydride monomer containing tetrahydrocurcumin shown in Formula I is as follows:

[0019] S1. Tetrahydrocurcumin is reacted with boron tribromide to obtain intermediate 1, the structure of which is as follows:

[0020]

[0021] S2. 4,5-dichlorophthalic anhydride and methylamine are reacted to obtain intermediate 2, the structure of which is as follows:

[0022]

[0023] S3. Intermediate 1 and intermediate 2 are reacted to obtain intermediate 3, the structure of which is as follows:

[0024]

[0025] S4. The intermediate 3 is reacted with a base and then acidified to obtain the product.

[0026] As a further improvement of the present invention, the preparation method of the tetrahydrocurcumin-containing dianhydride monomer represented by Formula II is as follows:

[0027] T1. Tetrahydrocurcumin and N-methyl-3-nitrophthalimide were reacted to obtain intermediate 4, the structure of which is as follows:

[0028] T2. The intermediate 4 is subjected to a base-catalyzed reaction and acid precipitation to obtain the product.

[0029] As a further improvement of the present invention, the preparation method of the diamine monomer containing tetrahydrocurcumin represented by formula III is as follows: tetrahydrocurcumin and p-chloroaniline are reacted to obtain a product.

[0030] As a further improvement of the present invention, the preparation method of the diamine monomer containing tetrahydrocurcumin represented by formula IV is as follows:

[0031] U1. Tetrahydrocurcumin is reacted with boron tribromide to prepare intermediate 1;

[0032] U2. The intermediate 1 is reacted with 3,4-dichloroaniline to obtain the product.

[0033] The present invention further protects the application of the above-mentioned bio-based polyimide in biomedical materials, flexible display devices, and industrial insulation and environmentally friendly packaging.

[0034] The present invention has the following beneficial effects:

[0035] The invention uses tetrahydrocurcumin as a raw material, prepares two dianhydrides and two diamines respectively, and reacts them in pairs to prepare four bio-based polyimide materials. The raw material cost is low, the reaction conditions are mild, the preparation method is simple, the process is stable, the prepared products are safe and environmentally friendly, and the prepared polyimide materials not only have excellent mechanical properties, electrical properties and high and low temperature resistance, but also have good antibacterial and antioxidant effects.

[0036] The alkyl chain of the curcumin skeleton in the present invention makes the prepared bio-based polyimide material have good flexibility and processability. The polycyclic structure improves the gas permeability and light transmittance of the material, and has good solvent resistance and corrosion resistance. The bio-based material makes it highly biocompatible and has broad application prospects. DETAILED DESCRIPTION

[0037] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0038] Preparation Example 1 Preparation of Dianhydride Monomer Containing Tetrahydrocurcumin as Shown in Formula I

[0039] Here’s how:

[0040] S1. Dissolve 0.01 mol of tetrahydrocurcumin in 50 mL of dichloromethane. Add 30 mL of a dichloromethane solution containing 0.08 mol of boron tribromide at -78°C dropwise. After the addition is complete, stir and insulate for 30 minutes. Then naturally warm to room temperature and react with stirring for 12 hours. Add 100 mL of ice water to quench the reaction. Wash until the solution is neutral. Collect the organic phase by extraction, remove the solvent under reduced pressure, and recrystallize from acetone / petroleum ether (volume ratio 3:1) to obtain intermediate 1. ESI-MS calculated value: C 19 H 21 O6(M+H) + 345.13, found: 345.1, yield 75%.

[0041] NMR results: 1 H NMR (300MHz, CDCl3) δ6.52 (m, 4H), 6.43 (s, 2H), 5.02 (br, 4H), 3.65 (s, 2H), 2.75 (m, 8H).

[0042] S2. Dissolve 0.01 mol of 4,5-dichlorophthalic anhydride in 30 mL of acetic acid, add dropwise a 30 wt% aqueous solution of methylamine (0.015 mol of methylamine), heat under reflux for 5 h, cool to 4°C, filter, wash, and dry to obtain intermediate 2; ESI-MS calculated value: C9H6Cl2NO2 (M+H) + 229.97, found: 230.0, yield: 81%.

[0043] NMR results: 1 H NMR (300MHz, CDCl3) δ8.10 (s, 2H), 3.17 (s, 3H).

[0044] S3. Add 0.01 mol of intermediate 1 and 0.02 mol of sodium carbonate to 100 mL of toluene, heat under reflux and stir for 1 h, add 0.022 mol of intermediate 2 under nitrogen protection, keep warm and react for 10 h, cool to room temperature, filter, wash, and dry to obtain intermediate 3; ESI-MS calculated value: C 37 H 27 N2O 10 (M+H) + 659.16, found: 659.2, yield: 67%.

[0045] NMR results: 1 H NMR (300MHz, CDCl3) δ7.75 (s, 4H), 6.8-6.84 (m, 6H), 3.62 (s, 2H), 3.17 (s, 6H), 2.77-2.79 (m, 8H).

[0046] S4. Add 0.01 mol of intermediate 3 and 0.015 mol of KOH to 100 mL of deionized water, heat under reflux for 27 h, cool to room temperature, filter, add 200 mL of 5 mol / L hydrochloric acid to the filtrate, filter, and recrystallize the solid from petroleum ether to obtain the product. ESI-MS calculated value: C 35 H 21 O 12 (M+H) + 633.10, found: 633.1, yield 96%.

[0047] NMR results: 1 H NMR (300MHz, CDCl3) δ7.98 (s, 4H), 6.80-6.83 (m, 6H), 3.64 (s, 2H), 2.75-2.77 (m, 8H).

[0048] Preparation Example 2 Preparation of Dianhydride Monomer Containing Tetrahydrocurcumin Shown in Formula II

[0049] Here’s how:

[0050] T1. Add 0.01 mol of tetrahydrocurcumin and 0.021 mol of potassium carbonate to 100 mL of toluene and heat under reflux for 1 h under nitrogen. Add 0.0205 mol of N-methyl-3-nitrophthalimide and keep the reaction warm for 17 h. Cool to room temperature and add 100 mL of 2 mol / L hydrochloric acid. Filter, wash the solid, dry, and recrystallize from acetic acid to obtain intermediate 4; ESI-MS calculated value: C 39 H 35 N2O 10 (M+H) + 691.22, found: 691.2, yield 70%.

[0051] NMR results: 1 H NMR (300MHz, CDCl3) δ7.86 (d, J=5.5Hz, 2H), 7.67 (m, 2H), 7.31 (d, J=6.7Hz, 2H) , 6.62-6.69(m, 6H), 3.72(s, 6H), 3.65(s, 2H), 3.19(s, 6H), 2.77-2.79(m, 8H).

[0052] T2. Add 0.01 mol of intermediate 4 to 100 mL of deionized water, add 0.01 mol of NaOH, heat under reflux for 20 h, cool to room temperature, add 100 mL of 2 mol / L hydrochloric acid, filter, wash the solid, dry, and recrystallize from acetic acid to obtain the product. ESI-MS calculated value: C 37 H 30 O 12 (M+H) + 665.16, found: 665.2, yield 94%.

[0053] NMR results: 1 H NMR (300MHz, CDCl3) δ 8.09 (d, J=5.9Hz, 2H), 7.79 (m, 2H), 7.45 (d, J=6.2Hz, 2H), 6.68-6.72 (m, 6H), 3.75 (s, 6H), 3.61 (s, 2H), 2.77-2.79 (m, 8H).

[0054] Preparation Example 3 Preparation of a diamine monomer containing tetrahydrocurcumin represented by formula III

[0055] The method is as follows: 0.0105 mol of tetrahydrocurcumin and 0.03 mol of triethylamine are dissolved in 200 mL of dichloromethane. Under nitrogen protection, 0.02 mol of p-chloroaniline is added, and the mixture is heated under reflux for 4 hours. The mixture is cooled to 4°C, filtered, washed, and dried to obtain the product. ESI-MS calculated value: C 33 H 35 N2O6(M+H) + 555.24, found: 555.2, yield: 82%.

[0056] NMR results: 1 H NMR (300MHz, CDCl3) δ6.79 (d, J=6.2Hz, 2H), 6.61-6.67 (m, 8H), 6.42 (m, 4H), 4.05 (br, 4H), 3.73 (s, 6H), 3.62 (s, 2H), 2.77-2.78 (m, 8H).

[0057] Preparation Example 4 Preparation of a diamine monomer containing tetrahydrocurcumin represented by Formula IV

[0058] Here’s how:

[0059] U1. 0.01 mol of tetrahydrocurcumin was dissolved in 50 mL of dichloromethane, and 30 mL of a dichloromethane solution containing 0.08 mol of boron tribromide was added dropwise at -78 ° C. After the addition was complete, the mixture was stirred for 30 min, naturally warmed to room temperature, and stirred for 12 h. The reaction was quenched by adding 100 mL of ice water, and the solution was washed until neutral. The organic phase was extracted and collected, the solvent was removed under reduced pressure, and recrystallized from acetone / petroleum ether (volume ratio 3:1) to obtain Intermediate 1 with a yield of 75%, the same as in Step S1 of Preparation Example 1;

[0060] U2. Add 0.011 mol of intermediate 1 and 0.02 mol of potassium carbonate to 100 mL of toluene and heat under reflux for 30 min. Under nitrogen protection, add 0.02 mol of 3,4-dichloroaniline and keep the reaction warm for 7 h. Cool to room temperature, filter, wash, and dry to obtain the product. ESI-MS calculated value: C 31 H 27 N2O6(M+H) + 523.18, found: 523.2, yield: 86%.

[0061] NMR results: 1H NMR (300MHz, CDCl3) δ6.8-6.83 (m, 4H), 6.72 (s, 2H), 6.64 (d, J=6.3Hz, 2H), 6.1 5(d, J=6.2Hz, 2H), 6.05(s, 2H), 4.02(br, 4H), 3.61(s, 2H), 2.75-2.78(m, 8H).

[0062] Example 1

[0063] This embodiment provides a method for preparing a bio-based polyimide, comprising the following steps:

[0064] 0.5 mol of the dianhydride monomer containing tetrahydrocurcumin represented by formula I obtained in Preparation Example 1 and 0.5 mol of the diamine monomer containing tetrahydrocurcumin represented by formula III obtained in Preparation Example 3 were added to 500 mL of a polar aprotic solvent, heated to 70° C., stirred and reacted for 3 hours, then heated to 170° C., stirred and reacted for 15 hours, cooled to room temperature, poured into 500 mL of ethanol, filtered, and the precipitate was extracted with ethanol Soxhlet for 5 hours and dried to obtain a bio-based polyimide. The dried bio-based polyimide material was dissolved in N,N-dimethylformamide, stirred for 3 hours, and then coated with a coater to obtain a bio-based polyimide film with a thickness of 25-30 nm.

[0065] Example 2

[0066] This embodiment provides a method for preparing a bio-based polyimide, comprising the following steps:

[0067] 0.5 mol of the tetrahydrocurcumin-containing dianhydride monomer of formula I obtained in Preparation Example 1 and 0.5 mol of the tetrahydrocurcumin-containing diamine monomer of formula IV obtained in Preparation Example 4 were added to 500 mL of a polar aprotic solvent, heated to 80° C., stirred and reacted for 5 hours, then heated to 180° C., stirred and reacted for 17 hours, cooled to room temperature, poured into 500 mL of ethanol, filtered, and the precipitate was extracted with ethanol Soxhlet for 7 hours and dried to obtain a bio-based polyimide. The dried bio-based polyimide material was dissolved in N,N-dimethylformamide, stirred for 3 hours, and then coated with a coater to obtain a bio-based polyimide film with a thickness of 25-30 nm.

[0068] Example 3

[0069] This embodiment provides a method for preparing a bio-based polyimide, comprising the following steps:

[0070] 0.5 mol of the dianhydride monomer containing tetrahydrocurcumin represented by formula II obtained in Preparation Example 2 and 0.5 mol of the diamine monomer containing tetrahydrocurcumin represented by formula III obtained in Preparation Example 3 were added to 500 mL of a polar aprotic solvent, heated to 75° C., stirred and reacted for 4 hours, then heated to 175° C., stirred and reacted for 16 hours, cooled to room temperature, poured into 500 mL of ethanol, filtered, and the precipitate was extracted with ethanol Soxhlet for 6 hours and dried to obtain a bio-based polyimide. The dried bio-based polyimide material was dissolved in N,N-dimethylformamide, stirred for 3 hours, and then coated with a coater to obtain a bio-based polyimide film with a thickness of 25-30 nm.

[0071] Example 4

[0072] This embodiment provides a method for preparing a bio-based polyimide, comprising the following steps:

[0073] 0.5 mol of the dianhydride monomer containing tetrahydrocurcumin represented by formula II obtained in Preparation Example 2 and 0.5 mol of the diamine monomer containing tetrahydrocurcumin represented by formula IV obtained in Preparation Example 4 were added to 500 mL of a polar aprotic solvent, heated to 75° C., stirred and reacted for 5 hours, then heated to 175° C., stirred and reacted for 16 hours, cooled to room temperature, poured into 500 mL of ethanol, filtered, and the precipitate was extracted with ethanol Soxhlet for 7 hours and dried to obtain a bio-based polyimide. The dried bio-based polyimide material was dissolved in N,N-dimethylformamide, stirred for 3 hours, and then coated with a coater to obtain a bio-based polyimide film with a thickness of 25-30 nm.

[0074] Comparative Example 1

[0075] A polyimide film with the same thickness range as that prepared in Example 3 of Chinese invention patent application CN 112321828 A was used.

[0076] The polyimide film is composed of a bio-based fluorinated polyimide resin represented by the following formula:

[0077]

[0078] Comparative Example 2

[0079] A polyimide film with the same thickness range as that prepared in Example 4 of Chinese invention patent CN 114507345 B was used.

[0080] The polyimide film is composed of a bio-based fluorinated polyimide resin represented by the following formula, wherein n=28-31 and R=CH3:

[0081]

[0082] Test Example 1

[0083] The bio-based polyimide films prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to mechanical property tests.

[0084] Tested according to GB / T 1040.4-2006 standard, the tensile speed is 20mm / min.

[0085] The results are shown in Table 1.

[0086] Table 1

[0087]

[0088]

[0089] It can be seen from the above table that the bio-based polyimide films prepared in Examples 1-4 of the present invention have good mechanical properties.

[0090] Test Example 2

[0091] The bio-based polyimide films prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to light transmittance tests.

[0092] The film was cut into small pieces of 2 cm × 3 cm, and a UV-visible spectrometer was set up to test the transmittance at wavelengths of 450 nm and 600 nm.

[0093] The results are shown in Table 2.

[0094] Table 2

[0095]

[0096] It can be seen from the above table that the bio-based polyimide films prepared in Examples 1-4 of the present invention have good light transmittance.

[0097] Test Example 3

[0098] The bio-based polyimide films prepared in Examples 1-4 of the present invention and Comparative Examples 1-2 were tested for thermal properties and dielectric constants.

[0099] The results are shown in Table 3.

[0100] Table 3

[0101]

[0102] It can be seen from the above table that the bio-based polyimide films prepared in Examples 1-4 of the present invention have good thermal stability and low dielectric constant.

[0103] Test Example 4

[0104] The bio-based polyimide films prepared in Examples 1-4 of the present invention and Comparative Examples 1-2 were subjected to antibacterial tests.

[0105] The test was conducted according to the test method 1 of the standard GB21551.2-2010, and the bacteria used for the test were: Escherichia coli ATCC25922; Staphylococcus aureus ATCC25023; Candida albicans ATCC10231; 5 samples were tested in parallel for each embodiment and comparative example, and the average value was taken.

[0106] The results are shown in Table 4.

[0107] Table 4

[0108]

[0109]

[0110] It can be seen from the above table that the bio-based polyimide films prepared in Examples 1-4 of the present invention have good antibacterial properties.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A bio-based polyimide, characterized in that It has the following structure: Wherein, n=10-1000.

2. A method for preparing a bio-based polyimide according to claim 1, characterized in that: The following steps are involved: A dianhydride monomer containing tetrahydrocurcumin and a diamine monomer containing tetrahydrocurcumin are added to a polar aprotic solvent, heated to a first temperature for reaction, then heated to a second temperature for reaction, cooled to room temperature, poured into ethanol, filtered, precipitated, subjected to Soxhlet extraction with ethanol, and dried to obtain a bio-based polyimide; Wherein, the structural formula of the dianhydride monomer containing tetrahydrocurcumin is as shown in Formula I or Formula II: The structural formula of the diamine monomer containing tetrahydrocurcumin is shown in Formula III or Formula IV:

3. The preparation method according to claim 2, characterized in that The polar aprotic solvent is at least one of m-cresol, N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and dimethyl sulfoxide.

4. The preparation method according to claim 2, characterized in that The molar ratio of the dianhydride monomer containing tetrahydrocurcumin to the diamine monomer containing tetrahydrocurcumin is 0.9-1.1:0.9-1.

1.

5. The preparation method according to claim 2, characterized in that The temperature of the first temperature reaction is 70-80° C. and the time is 3-5 hours. The temperature of the second temperature reaction is 170-180° C. and the time is 15-17 hours. The time of the ethanol Soxhlet extraction is 5-7 hours.

6. The preparation method according to claim 2, characterized in that The preparation method of the tetrahydrocurcumin-containing dianhydride monomer shown in Formula I is as follows: S1. Tetrahydrocurcumin is reacted with boron tribromide to obtain intermediate 1, the structure of which is as follows: S2. 4,5-dichlorophthalic anhydride and methylamine are reacted to obtain intermediate 2, the structure of which is as follows: S3. Intermediate 1 and intermediate 2 are reacted to obtain intermediate 3, the structure of which is as follows: S4. The intermediate 3 is reacted with a base and then acidified to obtain the product.

7. The preparation method according to claim 2, characterized in that The preparation method of the tetrahydrocurcumin-containing dianhydride monomer shown in Formula II is as follows: T1. Tetrahydrocurcumin and N-methyl-3-nitrophthalimide were reacted to obtain intermediate 4, the structure of which is as follows: T2. The intermediate 4 is subjected to a base-catalyzed reaction and acid precipitation to obtain the product.

8. The preparation method according to claim 2, characterized in that The preparation method of the diamine monomer containing tetrahydrocurcumin represented by formula III is as follows: tetrahydrocurcumin and p-chloroaniline are reacted to obtain a product.

9. The preparation method according to claim 2, characterized in that The preparation method of the diamine monomer containing tetrahydrocurcumin shown in Formula IV is as follows: U1. Tetrahydrocurcumin is reacted with boron tribromide to prepare intermediate 1; U2. The intermediate 1 is reacted with 3,4-dichloroaniline to obtain the product.

10. Use of the bio-based polyimide according to claim 1 in biomedical materials, flexible display devices, and industrial insulation and environmentally friendly packaging.

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