Modified furyl polyamide and preparation method thereof

Abstract

The invention discloses modified furyl polyamide and a preparation method thereof, and belongs to the technical field of furyl polyamide preparation. The preparation method comprises the following steps: S1, dissolving 2-methyl-3-nitroaniline and paraformaldehyde in trifluoroacetic acid under an ice bath condition, stirring in an inert gas atmosphere, adding pure water, continuously stirring, adjusting the pH value, filtering, refluxing at normal temperature, and drying in vacuum to obtain a diamine precursor; the preparation method comprises the following steps: dispersing a diamine precursor in absolute ethyl alcohol in a nitrogen atmosphere, adding Pd / C, uniformly mixing, slowly dropwise adding N2H4.H2O, heating, refluxing, adding deionized water, filtering, washing, and drying in vacuum to obtain a diamine monomer; s2, a diamine monomer and 2, 5-furandicarbonyl chloride are subjected to a reaction, and furyl polyamide is prepared; and S3, uniformly mixing furyl polyamide, DMF and NaH, adding bromohydrocarbon, carrying out a stirring reaction in an inert gas, adding the obtained product into ice water, filtering, washing, and carrying out vacuum drying to obtain the modified furyl polyamide.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of furanyl polyamides, and particularly relates to a modified furanyl polyamide and a preparation method thereof. Background Art

[0002] As a core component, the lithium-ion battery separator physically isolates the positive and negative electrodes to prevent short circuits, and its performance directly affects the battery capacity, cycle life, and safety. Currently, the mainstream polyethylene (PE) and polypropylene (PP) microporous separators have advantages such as low cost, high mechanical strength, excellent electrochemical stability, and a controllable microporous structure. However, the difference between the closed pore temperature (about 130 °C) and the melting temperature (about 160 °C) is too small, and the separator is prone to melt and shrink at high temperatures, causing electrode contact and leading to the risk of thermal runaway. This thermodynamic defect has become a bottleneck for the safe application of high-energy-density batteries. Therefore, developing new separators with both high porosity ion conductivity and high-temperature thermal stability (such as ceramic-coated modification, aramid fibers, or new polymer-based materials) is a key research direction for improving the safety performance of batteries.

[0003] The patent application with the publication number CN117164849 A discloses a preparation method of a furanyl flexible polyamide, which mainly includes components such as 2,5-furandicarboxylic acid, diaminopolyether, long-chain diamine, and 2,5-furandicarboxylate. The specific steps are as follows: (1) Using solution polymerization, 2,5-furandicarboxylic acid and diaminopolyether are made into a prepolymer; (2) Melting and copolymerizing components such as 2,5-furandicarboxylate, long-chain diamine, and the prepolymer to obtain a furanyl flexible polyamide material. While having good flexibility, the introduction of flexible chain segments may reduce the glass transition temperature of the material, and it is prone to creep or deformation at high temperatures.

[0004] Therefore, improving the thermodynamic and mechanical properties of the new polyamide material, thereby enhancing the heat resistance and mechanical properties of the separator, is the main problem to be solved at present. Summary of the Invention

[0005] The purpose of the present invention is to provide a modified furanyl polyamide and a preparation method thereof to improve the heat resistance and mechanical properties of the polyamide material.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A preparation method of a modified furanyl polyamide, comprising the following steps:

[0008] S1. Dissolve 2-methyl-3-nitroaniline and paraformaldehyde in trifluoroacetic acid under ice bath conditions, stir in an inert gas atmosphere, add pure water, adjust the pH, filter, reflux at room temperature, and dry under vacuum to obtain a diamine precursor. Disperse the diamine precursor in absolute ethanol, add Pd / C and mix well, then slowly dropwise add N2H4·H2O, heat under reflux, add deionized water, filter and wash, and dry under vacuum to obtain a diamine monomer;

[0009] S2. Under an inert gas atmosphere, dissolve the diamine monomer in an organic solvent to form a diamine solution; within the range of -10 to 30 °C, add 2,5-furandicarbonyl chloride to the diamine solution in an inert gas atmosphere and continuously react until a furanyl polyamide with the desired molecular weight is obtained;

[0010] S3. Mix the furanyl polyamide, DMF and NaH evenly, add bromohydrocarbon, stir and react under an inert gas, then add to ice water, filter and wash, and dry under vacuum to obtain a modified furanyl polyamide.

[0011] Further, the dosage ratio of the 2-methyl-3-nitroaniline, paraformaldehyde, trifluoroacetic acid and pure water is (10 - 15) g : (4 - 6) g : (120 - 180) mL : (150 - 250) mL.

[0012] Further, the dosage ratio of the diamine precursor, absolute ethanol, Pd / C, N2H4·H2O and deionized water is (4 - 6) g : (80 - 120) mL : (0.4 - 0.6) g : (8 - 12) mL : (80 - 150) mL.

[0013] Further, the stirring time under the inert gas atmosphere is 44 - 48 h.

[0014] Further, the pH is adjusted to 8.5 - 9.0.

[0015] Further, the reflux at room temperature is reflux in an acetone solution for 1 - 2 h; the heating reflux time is 8 - 10 h.

[0016] Further, the dosage ratio of the diamine monomer, organic solvent and 2,5-furandicarbonyl chloride is (2 - 4) g : (30 - 50) mL : (1.5 - 3) g.

[0017] Further, the organic solvent is one or more of DMF, NMP, DCE, DCM.

[0018] Further, the dosage ratio of the furanyl polyamide, DMF, NaH, bromohydrocarbon and ice water is (1.5 - 2.5) g : (15 - 30) mL : (0.4 - 0.6) g : (2 - 4) g : (400 - 600) mL.

[0019] Further, the bromohydrocarbon is one or a combination of several of C8H17-Br, C5H11-Br, C3H7-Br, C2H5-Br, and Bn-Br.

[0020] Further, the stirring reaction time is 10 - 12 h.

[0021] Further, the washing is carried out three times with anhydrous methanol, and the vacuum drying temperature is 50 - 70 °C.

[0022] A modified furanyl polyamide is prepared by the preparation method of the above-mentioned modified furanyl polyamide.

[0023] Advantages of the present invention:

[0024] (1) For the preparation method of a modified furanyl polyamide provided by the present invention, two diamine functional groups in the prepared diamine monomer can react with acyl chloride to form polyamide; it has a unique V-shaped rigid structure, which restricts the movement of polymer molecular chains, not only improving the mechanical strength (such as tensile modulus) of the material and reducing creep deformation under long-term stress, but also significantly increasing the glass transition temperature of the material, making it have excellent stability at high temperatures.

[0025] (2) The bromohydrocarbon used in the present invention adds the bromohydrocarbon to the polyamide side chain through an affinity substitution method to improve the overall performance of the material (different bromohydrocarbons can endow new properties), and the crosslinking of the long-chain structure can also reduce solvent permeability and avoid excessive swelling of the material.

[0026] (3) For the modified furanyl polyamide provided by the present invention, when applied to a lithium battery separator, its microporous structure enhances the adsorption capacity of the separator for the electrolyte, forms a uniform liquid electrolyte layer, reduces local polarization, and improves the charge and discharge efficiency of the battery. Specific embodiments

[0027] The following describes the specific embodiments of the present invention in detail, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0028] Example 1

[0029] This example provides a modified furanyl polyamide, which is prepared by the following steps:

[0030] S1. Dissolve 12 g of 2-methyl-3-nitroaniline and 5 g of paraformaldehyde in 150 mL of trifluoroacetic acid under ice bath conditions, stir for 48 h under an inert gas atmosphere at room temperature, add 200 mL of pure water and continue stirring, adjust the pH to 8.5, filter, reflux in 300 mL of acetone solution for 2 h, cool and then vacuum dry at 60 °C to obtain a diamine precursor; under a nitrogen atmosphere, disperse 5 g of the diamine precursor in 100 mL of absolute ethanol, add 0.5 g of Pd / C (10 wt% Pd), mix well, and slowly dropwise add 10 mL of N 2 H 4 ·H 2 O, heat under reflux for 8 h, add 120 mL of deionized water, filter, wash three times with absolute methanol, and vacuum dry at 60 °C to obtain a diamine monomer;

[0031] S2. Under an inert gas atmosphere, dissolve 3 g of the diamine monomer in 40 mL of DMF to form a diamine solution; within the range of -10 to 30 °C, add 2 g of 2,5-furandicarbonyl chloride to the diamine solution under an inert gas atmosphere, and continue the reaction until a furanyl polyamide with the desired molecular weight is obtained;

[0032] S3. After mixing 2 g of the furanyl polyamide, 25 mL of DMF and 0.5 g of NaH evenly, add 3 g of C 8 H 17 -Br, stir and react for 12 h under an inert gas, add to 500 mL of ice water, filter, wash three times with absolute methanol, and vacuum dry at 60 °C to obtain a modified furanyl polyamide.

[0033] Example 2

[0034] The difference between this example and Example 1 is that the amount of the diamine precursor is increased. The specific implementation steps of S1 are as follows:

[0035] S1. Dissolve 12 g of 2-methyl-3-nitroaniline and 5 g of paraformaldehyde in 150 mL of trifluoroacetic acid under ice bath conditions, stir for 48 h under an inert gas atmosphere at room temperature, add 200 mL of pure water and continue stirring, adjust the pH to 8.5, filter, reflux in 300 mL of acetone solution for 2 h, cool and then vacuum dry at 60 °C to obtain a diamine precursor; under a nitrogen atmosphere, disperse 6 g of the diamine precursor in 100 mL of absolute ethanol, add 0.4 g of Pd / C (10 wt% Pd), mix well, and slowly dropwise add 10 mL of N 2 H 4 ·H 2 O, heat under reflux for 8 h, add 120 mL of deionized water, filter, wash three times with absolute methanol, and vacuum dry at 60 °C to obtain a diamine monomer;

[0036] The remaining raw materials and the preparation process are the same as those in Example 1.

[0037] Example 3

[0038] Compared with Example 1, the difference in this example is that the amount of diamine precursor is reduced. The specific implementation steps of S1 are as follows:

[0039] S1. Under ice bath conditions, dissolve 12 g of 2-methyl-3-nitroaniline and 5 g of paraformaldehyde in 150 mL of trifluoroacetic acid. Stir for 48 h under an inert gas atmosphere at room temperature, add 200 mL of pure water and continue stirring. Adjust the pH to 8.5, filter, reflux in 300 mL of acetone solution for 2 h, cool, and vacuum dry at 60 °C to obtain the diamine precursor. Under a nitrogen atmosphere, disperse 4 g of the diamine precursor in 100 mL of absolute ethanol, add 0.6 g of Pd / C (10 wt% Pd), mix well, and slowly dropwise add 10 mL of N 2 H 4 ·H 2 O, heat under reflux for 8 h, add 120 mL of deionized water, filter, wash three times with absolute methanol, and vacuum dry at 60 °C to obtain the diamine monomer;

[0040] The remaining raw materials and the preparation process are the same as those in Example 1.

[0041] Example 4

[0042] Compared with Example 1, the difference in this example is that the amount of diamine monomer is increased. The specific implementation steps of S2 are as follows:

[0043] S2. Under an inert gas atmosphere, dissolve 4 g of the diamine monomer in 40 mL of DMF to form a diamine solution. At -10 to 30 °C, add 1.5 g of 2,5-furandicarbonyl chloride to the diamine solution under an inert gas atmosphere and continue the reaction until the desired molecular weight of the furanyl polyamide is obtained;

[0044] The remaining raw materials and the preparation process are the same as those in Example 1.

[0045] Example 5

[0046] Compared with Example 1, the difference in this example is that the amount of diamine monomer is reduced. The specific implementation steps of S2 are as follows:

[0047] S2. Under an inert gas atmosphere, dissolve 2 g of the diamine monomer in 40 mL of DMF to form a diamine solution. At -10 to 30 °C, add 3 g of 2,5-furandicarbonyl chloride to the diamine solution under an inert gas atmosphere and continue the reaction until the desired molecular weight of the furanyl polyamide is obtained;

[0048] The remaining raw materials and the preparation process are the same as those in Example 1.

[0049] Example 6

[0050] This example is different from Example 1 in that the amount of furanyl polyamide is increased. The specific implementation steps of S3 are as follows:

[0051] S3. After uniformly mixing 2.5 g of furanyl polyamide, 25 mL of DMF, and 0.4 g of NaH, add 2 g of C 8 H 17 -Br. After stirring and reacting for 12 h under an inert gas, add it to 500 mL of ice water. After filtration, wash it three times with anhydrous methanol and vacuum dry it at 60 °C to obtain modified furanyl polyamide.

[0052] The remaining raw materials and the preparation process are the same as those in Example 1.

[0053] Example 7

[0054] This example is different from Example 1 in that the amount of furanyl polyamide is decreased. The specific implementation steps of S3 are as follows:

[0055] S3. After uniformly mixing 1.5 g of furanyl polyamide, 25 mL of DMF, and 0.6 g of NaH, add 4 g of C 8 H 17 -Br. After stirring and reacting for 12 h under an inert gas, add it to 500 mL of ice water. After filtration, wash it three times with anhydrous methanol and vacuum dry it at 60 °C to obtain modified furanyl polyamide.

[0056] The remaining raw materials and the preparation process are the same as those in Example 1.

[0057] Example 8

[0058] This example is different from Example 1 in that “C 8 H 17 -Br” is changed to “C 3 H 7 -Br”. The specific implementation steps of S3 are as follows:

[0059] S3. After uniformly mixing 2 g of furanyl polyamide, 25 mL of DMF, and 0.5 g of NaH, add 3 g of C 8 H 17 -Br. After stirring and reacting for 12 h under an inert gas, add it to 500 mL of ice water. After filtration, wash it three times with anhydrous methanol and vacuum dry it at 60 °C to obtain modified furanyl polyamide.

[0060] The remaining raw materials and the preparation process are the same as those in Example 1.

[0061] Example 9

[0062] Compared with Example 1, the difference in this example is that "C 8 H 17 -Br" is changed to "Bn-Br", and the specific implementation steps of S3 are as follows:

[0063] S3. After uniformly mixing 2 g of furanyl polyamide, 25 mL of DMF and 0.5 g of NaH, add 3 g of C 8 H 17 -Br, stir and react for 12 h under an inert gas, add to 500 mL of ice water, filter, wash three times with anhydrous methanol, and vacuum dry at 60 °C to obtain modified furanyl polyamide.

[0064] The remaining raw materials and the preparation process are the same as those in Example 1.

[0065] Comparative Example 1

[0066] Compared with Example 1, the difference in this comparative example is that the addition step of S3 is not carried out, and the specific implementation steps are as follows:

[0067] S1. Under ice bath conditions, dissolve 12 g of 2-methyl-3-nitroaniline and 5 g of paraformaldehyde in 150 mL of trifluoroacetic acid, stir for 48 h under an inert gas atmosphere at room temperature, add 200 mL of pure water and continue to stir, adjust the pH to 8.5, filter, reflux in 300 mL of acetone solution for 2 h, cool and vacuum dry at 60 °C to obtain a diamine precursor; under a nitrogen atmosphere, disperse 5 g of the diamine precursor in 100 mL of absolute ethanol, add 0.5 g of Pd / C (10 wt% Pd), mix well, and slowly drop in 10 mL of N 2 H 4 ·H 2 O, heat and reflux for 8 h, add 120 mL of deionized water, filter, wash three times with anhydrous methanol, and vacuum dry at 60 °C to obtain a diamine monomer;

[0068] S2. Under an inert gas atmosphere, dissolve 3 g of the diamine monomer in 40 mL of DMF to form a diamine solution; within the range of -10 to 30 °C, add 2 g of 2,5-furandicarbonyl chloride to the diamine solution under an inert gas atmosphere, and continue to react until the furanyl polyamide with the required molecular weight is obtained;

[0069] The remaining raw materials and the preparation process are the same as those in Example 1.

[0070] Comparative Example 2

[0071] Compared with Example 1, the difference in this comparative example is that "diamine monomer" is replaced by "m-phenylenediamine", and the specific implementation steps are as follows:

[0072] S1. Under an inert gas atmosphere, dissolve 3 g of m-phenylenediamine in 40 mL of DMF to form a diamine solution; within the range of -10 to 30 °C, add 2 g of 2,5-furandicarbonyl chloride to the diamine solution under an inert gas atmosphere, and continue the reaction until a furanyl polyamide with the desired molecular weight is obtained;

[0073] S2. After mixing 2 g of furanyl polyamide, 25 mL of DMF and 0.5 g of NaH evenly, add 3 g of C 8 H 17 -Br, stir and react for 12 h under an inert gas, then add it to 500 mL of ice water, filter and wash three times with anhydrous methanol, and dry in vacuo at 60 °C to obtain a modified furanyl polyamide.

[0074] The remaining raw materials and the preparation process are the same as those in Example 1.

[0075] Comparative Example 3

[0076] Compared with Example 1, the difference in this comparative example is that "diamine monomer" is replaced by "m-phenylenediamine", and the addition in step S3 is not carried out. The specific implementation steps are as follows:

[0077] S1. Under an inert gas atmosphere, dissolve 3 g of m-phenylenediamine in 40 mL of DMF to form a diamine solution; within the range of -10 to 30 °C, add 2 g of 2,5-furandicarbonyl chloride to the diamine solution under an inert gas atmosphere, and continue the reaction until a furanyl polyamide with the desired molecular weight is obtained;

[0078] The remaining raw materials and the preparation process are the same as those in Example 1.

[0079] Performance Test

[0080] Apply the modified furanyl polyamides prepared in Examples 1 - 9 and Comparative Examples 1 - 3 to lithium battery diaphragms, and conduct corresponding performance tests on them.

[0081] Thermal shrinkage rate: Test the thermal shrinkage rate of the obtained battery diaphragms according to GB / T 36363-2018 "Polyolefin Diaphragms for Lithium Ion Batteries";

[0082] Tensile strength: Test the tensile strength of the obtained battery diaphragms according to GB / T 36363-2018 "Polyolefin Diaphragms for Lithium Ion Batteries";

[0083] Battery capacity retention rate: Apply the above battery diaphragms to lithium iron phosphate batteries of the same specification, and test the capacity retention rate of the batteries after 200 cycles;

[0084] The results are shown in Table 1:

[0085] Table 1

[0086]

[0087]

[0088] As can be seen from Table 1, compared with Example 1, the differences in Examples 2-9 are only in the raw material ratio of the modified furanyl polyamide synthesis and the replacement of raw materials within a reasonable range. Judging from the results, after being applied to the battery separator, they all have excellent thermal stability and mechanical strength. Applying the battery separator to lithium batteries is also beneficial to improving the retention rate of battery capacity.

[0089] Compared with Example 1, after no bromohydrocarbon addition in Comparative Example 1, the thermal stability and mechanical properties of the material showed a downward trend; combined with Examples 8-9, it was found that due to its crosslinking, the long carbon chain can also reduce the solvent permeability and avoid excessive swelling of the material, which is beneficial to maintaining its long-term stability; compared with Example 1, the polyamide material prepared with conventional diamine in Comparative Example 2 has poor thermal stability and low mechanical properties compared with the polyamide material of the present invention. This is because the diamine structure adopted in the present invention has a unique V-shaped rigid structure, which restricts the movement of polymer molecular chains, not only improving the mechanical strength of the material, but also significantly increasing the glass transition temperature of the material, making it have excellent stability at high temperatures; compared with Comparative Examples 1-2, after not adopting the diamine structure and the addition step of the present invention simultaneously in Comparative Example 3, the material properties are greatly reduced, reflecting the synergy of crosslinking between the two.

[0090] In summary, a modified furanyl polyamide and its preparation method provided by the present invention have good heat resistance and mechanical stability, and have broad application prospects in the technical field of polyamide preparation.

[0091] The above-disclosed are only several specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for preparing a modified furan-based polyamide, characterized in that: The following steps are involved: S1. Dissolve 2-methyl-3-nitroaniline and polyformaldehyde in trifluoroacetic acid under ice bath conditions, stir under an inert gas atmosphere, add pure water, adjust the pH, filter, reflux at room temperature, and vacuum dry to obtain a diamine precursor, disperse the diamine precursor in anhydrous ethanol, add Pd / C to mix, slowly drop N2H4·H2O, heat to reflux, add deionized water, filter, wash, and vacuum dry to obtain a diamine monomer; S2, reacting a diamine monomer with 2,5-furandicarboxylic acid chloride to prepare a furan-based polyamide; S3. After the furan-based polyamide, DMF and NaH are uniformly mixed, a brominated hydrocarbon is added, and the mixture is stirred for reaction under an inert gas, then added into ice water, filtered and washed, and vacuum dried to obtain a modified furan-based polyamide.

2. The method for preparing a modified furan-based polyamide according to claim 1, characterized in that: The specific steps of preparing furan-based polyamide are as follows: Under an inert gas atmosphere, a diamine monomer is dissolved in an organic solvent to form a diamine solution; 2,5-furandicarboxylic acid chloride is added to the diamine solution at -10 to 30° C. under an inert gas atmosphere, and the reaction is continued until a furan-based polyamide with a desired molecular weight is obtained.

3. The method for preparing a modified furan-based polyamide according to claim 1, characterized in that: The usage ratio of the 2-methyl-3-nitroaniline, paraformaldehyde, trifluoroacetic acid and pure water is (10-15) g: (4-6) g: (120-180) mL: (150-250) mL.

4. The method for preparing a modified furan-based polyamide according to claim 1, characterized in that: The usage ratio of the diamine precursor, anhydrous ethanol, Pd / C, N2H4·H2O and deionized water is (4-6) g: (80-120) mL: (0.4-0.6) g: (8-12) mL: (80-150) mL.

5. The method for preparing a modified furan-based polyamide according to claim 1, characterized in that: The stirring time under the inert gas atmosphere is 44-48 hours; the pH is adjusted to 8.5-9.0; the room temperature reflux is reflux in the acetone solution for 1-2 hours; and the heating reflux time is 8-10 hours.

6. The method for preparing a modified furan-based polyamide according to claim 2, characterized in that: The usage ratio of the diamine monomer, the organic solvent and 2,5-furandicarboxylic acid chloride is (2-4) g: (30-50) mL: (1.5-3) g; the organic solvent is one or more of DMF, NMP, DCE and DCM.

7. The method for preparing a modified furan-based polyamide according to claim 1, characterized in that: The usage ratio of the furan-based polyamide, DMF, NaH, bromohydrocarbon and ice water is (1.5-2.5) g: (15-30) mL: (0.4-0.6) g: (2-4) g: (400-600) mL.

8. The method for preparing a modified furan-based polyamide according to claim 1, characterized in that: The bromohydrocarbon is C8H 17 -Br, C5H 11 -Br, C3H7-Br, C2H5-Br and Bn-Br, or a combination of several thereof.

9. The method for preparing a modified furan-based polyamide according to claim 1, characterized in that: The stirring reaction time is 10-12 hours; the washing is three times of washing with anhydrous methanol, and the vacuum drying temperature is 50-70°C.

10. A modified furan-based polyamide, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 9.

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