Hydrophilic modified polyimide material and preparation process thereof

Abstract

The invention relates to the technical field of polyimide, and discloses a hydrophilic modified polyimide material and a preparation process thereof.The reaction proportion of N, N-bis (2-ethoxyl) ethylenediamine is regulated, so that functional groups such as hydroxyl and carboxyl are controllably introduced to the surface of polyimide, and with the increase of the carboxyl content on the surface of polyimide, the hydrophilic modified polyimide material is prepared. Compared with the prior art, the hydrophilic modified polyimide material has the advantages that the water contact angle of the material is smaller and smaller, the hydrophilicity is better and better, the tensile strength and bending strength of the hydrophilic modified polyimide material are slightly reduced compared with those of unmodified polyimide, the elongation at break is slightly improved, and excellent mechanical properties are still kept.

Description

Technical Field

[0001] The invention relates to the technical field of polyimide, in particular to a hydrophilic modified polyimide material and a preparation process thereof. Background Art

[0002] Polyimide is a special engineering material. Its main molecular chain contains imide rings, which makes polyimide exhibit excellent thermal properties, mechanical strength and other properties. It has important applications in coatings, fibers, films and other fields. The unmodified polyimide surface is hydrophobic and has poor hydrophilicity, which limits the practical application of polyimide. Therefore, it is necessary to modify polyimide to make it hydrophilic and improve its dyeability, biocompatibility and other properties.

[0003] At present, the methods for hydrophilic modification of polyimide mainly include low-temperature plasma modification, ultraviolet radiation modification, surface grafting modification, etc. Through surface grafting reaction, hydrophilic functional groups such as carboxyl and hydroxyl groups can be controllably introduced on the surface of polyimide, which can effectively improve its hydrophilicity. The present invention aims to introduce hydrophilic carboxyl groups on the surface of polyimide materials to improve the hydrophilicity of traditional polyimide materials. Summary of the invention

[0004] The technical problem solved by the invention is: preparing a hydrophilic modified polyimide containing carboxyl groups on the surface, solving the problem of poor hydrophilicity of traditional polyimide materials.

[0005] The technical solution of the present invention is: a preparation process of a hydrophilic modified polyimide material:

[0006] S1. Add hydroxyethyl polyimide and aqueous hydrogen bromide solution into a flask equipped with a reflux condenser, add concentrated sulfuric acid dropwise, react at a temperature of 55-60°C for 6-12h, cool, filter, wash with aqueous sodium bicarbonate solution and water in turn, and dry to obtain bromoethyl polyimide.

[0007] S2. Add bromoethyl polyimide, iminodiacetic acid and potassium carbonate aqueous solution into a flask, react at a temperature of 65-90° C. for 24-48 hours, filter, wash with dilute hydrochloric acid and water in sequence, and dry to obtain a hydrophilic modified polyimide material.

[0008] Furthermore, the mass fraction of the aqueous hydrogen bromide solution is 30-45%.

[0009] Furthermore, the volume ratio of the aqueous hydrogen bromide solution to concentrated sulfuric acid is 10:(1-1.5).

[0010] Furthermore, the mass fraction of the potassium carbonate aqueous solution is 6-20%.

[0011] Furthermore, the preparation method of the hydroxyethyl polyimide is:

[0012] S11. Add 4,4-diaminodiphenyl ether, N,N-bis(2-hydroxyethyl)ethylenediamine, dianhydride monomer and N-methylpyrrolidone solvent into a flask, and react at a temperature of 5-15°C for 24-48 hours. After the reaction, pour the solution into a glass mold and heat it gradually in an oven at a program of 120°C / 2h, 180°C / 3h, 220°C / 2h, 250°C / 2h and 280°C / 2h to obtain hydroxyethyl polyimide.

[0013] Furthermore, the molar ratio of the 4,4-diaminodiphenyl ether, N,N-bis(2-hydroxyethyl)ethylenediamine, and dianhydride monomer is (0.8-0.95):(0.05-0.2):1.

[0014] Furthermore, the dianhydride monomer is any one of pyromellitic anhydride, 4,4'-biphenyl ether dianhydride or 3,3',4,4'-biphenyltetracarboxylic anhydride.

[0015] The technical effect of the present invention is as follows: N, N-bis (2-hydroxyethyl) ethylenediamine is used as the third monomer to carry out polymerization reaction with 4, 4-diaminodiphenyl ether and dianhydride monomers to obtain hydroxyethyl polyimide, and then the hydroxyl group is brominated in a hydrogen bromide aqueous solution and concentrated sulfuric acid system to obtain bromoethyl polyimide, and finally under the catalysis of potassium carbonate, the bromine atom and the imino group of iminodiacetic acid undergo substitution reaction to obtain a hydrophilic modified polyimide material with a dicarboxyl structure on the surface.

[0016] The present invention controls the reaction ratio of N,N-bis(2-hydroxyethyl)ethylenediamine to controllably introduce functional groups such as hydroxyl groups and carboxyl groups on the surface of polyimide. As the content of carboxyl groups on the surface of polyimide increases, the water contact angle of the material becomes smaller and smaller, and the hydrophilicity becomes better and better. Compared with unmodified polyimide, the tensile strength and bending strength of the hydrophilically modified polyimide material decrease only slightly, and the elongation at break is slightly improved, while the excellent mechanical properties are still maintained. DETAILED DESCRIPTION

[0017] It should be noted that the following detailed descriptions are exemplary and are intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations and / or combinations thereof.

[0018] Example 1

[0019] Preparation process of hydroxyethyl polyimide: add 28.5mmol of 4,4-diaminodiphenyl ether, 1.5mmol N,N-bis(2-hydroxyethyl)ethylenediamine, 30mmol of pyromellitic anhydride, and 500mL of N-methylpyrrolidone solvent into a flask, react at 5°C for 48h, pour the solution into a glass mold after the reaction, and heat gradually in an oven at 120°C / 2h, 180°C / 3h, 220°C / 2h, 250°C / 2h, and 280°C / 2h to obtain hydroxyethyl polyimide.

[0020] Preparation process of bromoethyl polyimide: add 10g hydroxyethyl polyimide and 500mL of 30% hydrogen bromide aqueous solution into a flask equipped with a reflux condenser, add 50mL of concentrated sulfuric acid dropwise, react at 60°C for 8h, cool, filter, wash with sodium bicarbonate aqueous solution and water in turn, and dry to obtain bromoethyl polyimide.

[0021] Preparation process of hydrophilic modified polyimide material: add bromoethyl polyimide, iminodiacetic acid, and 6% potassium carbonate aqueous solution into a flask, react at 65°C for 36 hours, filter, wash with dilute hydrochloric acid and water in turn, and dry to obtain a hydrophilic modified polyimide material.

[0022] Example 2

[0023] Preparation process of hydroxyethyl polyimide: add 27.5mmol of 4,4-diaminodiphenyl ether, 2.5mmol N,N-bis(2-hydroxyethyl)ethylenediamine, 30mmol 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 400mL of N-methylpyrrolidone solvent into a flask, react at 5°C for 36h, pour the solution into a glass mold after the reaction, and perform gradient heating in an oven at a program of 120°C / 2h, 180°C / 3h, 220°C / 2h, 250°C / 2h, and 280°C / 2h to obtain hydroxyethyl polyimide.

[0024] Preparation process of bromoethyl polyimide: add 10g hydroxyethyl polyimide and 500mL of 35% hydrogen bromide aqueous solution into a flask equipped with a reflux condenser, add 60mL of concentrated sulfuric acid dropwise, react at 55°C for 12h, cool, filter, wash with sodium bicarbonate aqueous solution and water in turn, and dry to obtain bromoethyl polyimide.

[0025] Preparation process of hydrophilic modified polyimide material: add bromoethyl polyimide, iminodiacetic acid, and 10% potassium carbonate aqueous solution into a flask, react at 70°C for 36 hours, filter, wash with dilute hydrochloric acid and water in turn, and dry to obtain a hydrophilic modified polyimide material.

[0026] Example 3

[0027] Preparation process of hydroxyethyl polyimide: add 26mmol of 4,4-diaminodiphenyl ether, 4mmolN,N-bis(2-hydroxyethyl)ethylenediamine, 30mmol 4,4'-biphenyl ether dianhydride, and 500mL of N-methylpyrrolidone solvent into a flask, react at 15°C for 24h, pour the solution into a glass mold after the reaction, and heat it gradually in an oven at 120°C / 2h, 180°C / 3h, 220°C / 2h, 250°C / 2h, and 280°C / 2h to obtain hydroxyethyl polyimide.

[0028] Preparation process of bromoethyl polyimide: add 10g hydroxyethyl polyimide and 500mL of 35% hydrogen bromide aqueous solution into a flask equipped with a reflux condenser, add 65mL of concentrated sulfuric acid dropwise, react at 60°C for 12h, cool, filter, wash with sodium bicarbonate aqueous solution and water in turn, and dry to obtain bromoethyl polyimide.

[0029] Preparation process of hydrophilic modified polyimide material: add bromoethyl polyimide, iminodiacetic acid, and 15% potassium carbonate aqueous solution into a flask, react at 65°C for 48h, filter, wash with dilute hydrochloric acid and water in turn, and dry to obtain a hydrophilic modified polyimide material.

[0030] Example 4

[0031] Preparation process of hydroxyethyl polyimide: add 25mmol of 4,4-diaminodiphenyl ether, 5mmolN,N-bis(2-hydroxyethyl)ethylenediamine, 30mmol 4,4'-biphenyl ether dianhydride, and 500mL of N-methylpyrrolidone solvent into a flask, react at a temperature of 10°C for 24h, pour the solution into a glass mold after the reaction, and conduct gradient heating in an oven, the program is 120°C / 2h, 180°C / 3h, 220°C / 2h, 250°C / 2h, 280°C / 2h, to obtain hydroxyethyl polyimide.

[0032] Preparation process of bromoethyl polyimide: add 10g hydroxyethyl polyimide and 500mL of 40% hydrogen bromide aqueous solution into a flask equipped with a reflux condenser, add 70mL of concentrated sulfuric acid dropwise, react at 60°C for 12h, cool, filter, wash with sodium bicarbonate aqueous solution and water in turn, and dry to obtain bromoethyl polyimide.

[0033] Preparation process of hydrophilic modified polyimide material: add bromoethyl polyimide, iminodiacetic acid, and 15% potassium carbonate aqueous solution into a flask, react at 90°C for 24 hours, filter, wash with dilute hydrochloric acid and water in turn, and dry to obtain a hydrophilic modified polyimide material.

[0034] Example 5

[0035] Preparation process of hydroxyethyl polyimide: add 24mmol of 4,4-diaminodiphenyl ether, 6mmolN,N-bis(2-hydroxyethyl)ethylenediamine, 30mmol 4,4'-biphenyl ether dianhydride, and 500mL of N-methylpyrrolidone solvent into a flask, react at a temperature of 15°C for 24h, pour the solution into a glass mold after the reaction, and carry out gradient heating in an oven, the program is 120°C / 2h, 180°C / 3h, 220°C / 2h, 250°C / 2h, 280°C / 2h, to obtain hydroxyethyl polyimide.

[0036] Preparation process of bromoethyl polyimide: add 10g hydroxyethyl polyimide and 500mL of 40% hydrogen bromide aqueous solution into a flask equipped with a reflux condenser, add 70mL of concentrated sulfuric acid dropwise, react at 60°C for 12h, cool, filter, wash with sodium bicarbonate aqueous solution and water in turn, and dry to obtain bromoethyl polyimide.

[0037] Preparation process of hydrophilic modified polyimide material: add bromoethyl polyimide, iminodiacetic acid, and 20% potassium carbonate aqueous solution into a flask, react at 80°C for 36 hours, filter, wash with dilute hydrochloric acid and water in turn, and dry to obtain a hydrophilic modified polyimide material.

[0038] Comparative Example 1: The only difference from Example 1 is that when preparing polyimide, N,N-bis(2-hydroxyethyl)ethylenediamine is not added, the molar ratio of 4,4-diaminodiphenyl ether and pyromellitic anhydride is 1:1, and the amount used is 30 mmol, to obtain unmodified polyimide.

[0039] Comparative Example 2: The only difference from Example 1 is that only hydroxyethyl polyimide is prepared.

[0040] Comparative Example 3: The only difference from Example 1 is that only bromoethyl polyimide is prepared.

[0041] The water contact angle of polyimide was tested by an optical contact angle tester, and the mechanical properties of polyimide were tested by a universal material testing machine. The test results are shown in the following table:

[0042]

[0043] After the water contact angle test, in Examples 1-5, as the amount of N,N-bis(2-hydroxyethyl)ethylenediamine increased, more and more carboxyl groups were generated, which significantly reduced the water contact angle of the polyimide to a minimum of 48.6°, thereby enhancing the hydrophilicity of the polyimide.

[0044] Comparative Example 1 was prepared by polymerization using only 4,4-diaminodiphenyl ether and pyromellitic anhydride to obtain an unmodified polyimide, which had a water contact angle of 78.3° and had poor hydrophilicity.

[0045] The hydroxyethyl polyimide prepared in Comparative Example 2 contains hydrophilic hydroxyethyl groups and has a relatively small water contact angle of 65.6°.

[0046] The bromoethyl polyimide prepared in Comparative Example 3 does not contain a hydrophilic group and has a water contact angle that is not much different from that of the unmodified polyimide.

[0047] Compared with the unmodified polyimide in comparative example 1, the tensile strength and flexural strength of the hydrophilic polyimide prepared in examples 1-5 decreased slightly, and the elongation at break increased slightly. Therefore, the hydrophilic modification of the polyimide had little effect on its mechanical properties.

[0048] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A process for preparing a hydrophilic modified polyimide material, characterized in that: The hydrophilic modified polyimide material is prepared according to the following process: S1. Add hydroxyethyl polyimide and aqueous hydrogen bromide solution to a flask equipped with a reflux condenser, add concentrated sulfuric acid dropwise, react at a temperature of 55-60° C. for 6-12 hours, cool, filter, wash with aqueous sodium bicarbonate solution and water in sequence, and dry to obtain bromoethyl polyimide; S2. Add bromoethyl polyimide, iminodiacetic acid and potassium carbonate aqueous solution into a flask, react at a temperature of 65-90° C. for 24-48 hours, filter, wash with dilute hydrochloric acid and water in sequence, and dry to obtain a hydrophilic modified polyimide material.

2. The preparation process of the hydrophilic modified polyimide material according to claim 1, characterized in that: The mass fraction of the aqueous hydrogen bromide solution is 30-45%.

3. The preparation process of the hydrophilic modified polyimide material according to claim 2, characterized in that: The volume ratio of the aqueous hydrogen bromide solution to concentrated sulfuric acid is 10:(1-1.5).

4. The preparation process of the hydrophilic modified polyimide material according to claim 1, characterized in that: The mass fraction of the potassium carbonate aqueous solution is 6-20%.

5. The preparation process of the hydrophilic modified polyimide material according to claim 1, characterized in that: The preparation method of the hydroxyethyl polyimide is: S11. Add 4,4-diaminodiphenyl ether, N,N-bis(2-hydroxyethyl)ethylenediamine, dianhydride monomer and N-methylpyrrolidone solvent into a flask, and react at a temperature of 5-15°C for 24-48 hours. After the reaction, pour the solution into a glass mold and heat it gradually in an oven at a program of 120°C / 2h, 180°C / 3h, 220°C / 2h, 250°C / 2h and 280°C / 2h to obtain hydroxyethyl polyimide.

6. The process for preparing the hydrophilic modified polyimide material according to claim 5, characterized in that: The molar ratio of the 4,4-diaminodiphenyl ether, N,N-bis(2-hydroxyethyl)ethylenediamine and dianhydride monomer is (0.8-0.95):(0.05-0.2):

1.

7. The process for preparing the hydrophilic modified polyimide material according to claim 6, characterized in that: The dianhydride monomer is any one of pyromellitic anhydride, 4,4'-biphenyl ether dianhydride or 3,3',4,4'-biphenyltetracarboxylic anhydride.

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