Preparation method and application of melamine polymer hydrophilic modified PVDF composite material

Abstract

The invention relates to a preparation method and application of a melamine polymer hydrophilic modified PVDF (Polyvinylidene Fluoride) composite material. The preparation method comprises the following steps: dispersing hydrophobic PVDF nanoparticles in water, and adding an organic solvent to form a white uniform PVDF emulsion S1; dissolving melamine in a formaldehyde aqueous solution, or additionally adding a metal salt to form a clear solution S2; s1 is added into S2, and the mixed solution is kept in a uniform emulsion state; the melamine polymer hydrophilic modified PVDF composite material is prepared through a hydrothermal reaction and has hydrophilicity. Different from conventional hydrophilic modification, the method has the advantages that in-situ hydrophilic modification is carried out on the PVDF surface through a simple and easily-controlled hydrothermal treatment process, and the hydrophilic performance is improved. The melamine polymer surface functional groups and the spatial network structure are beneficial to loading of metal nanoparticles and providing of catalytic active components. The melamine polymer hydrophilic modified PVDF composite material can be applied to the fields of catalysis, oil-water separation, filtering membranes, coatings and the like, and the product performance is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterial preparation, and relates to the regulated preparation and application of a melamine polymer hydrophilic modified PVDF composite material. Background Art

[0002] Due to its high bond energy and low surface energy, polyvinylidene fluoride (PVDF) exhibits good stability and hydrophobicity, and is widely used in different fields. At the same time, the need for hydrophilic modification of PVDF has received attention. For example, in water treatment applications, its strong hydrophobicity may cause blockage due to the adsorption of organic pollutants such as oils and proteins, reduction of permeation flux, and attenuation of mechanical properties, thus shortening the service life, and hydrophilic modification is required to improve the performance. In catalytic reactions, PVDF has the effect of promoting catalytic activity improvement, and also requires hydrophilic modification to improve the performance of aqueous phase catalytic reactions.

[0003] The main method for hydrophilic modification of PVDF composite materials is to modify composite membranes. Modifying the surface structure of PVDF with organic materials is an effective way to enhance and optimize the hydrophilicity of materials. For example, the national invention patents "Preparation of superhydrophilic SiO2 / PDAus / PVDF composite membrane" (application number 202010496296.6), "A DOPA / PEI-MXene / PVDF hydrophilic anti-fouling composite membrane and its preparation method and application" (application number 202311360563.7), "A PVDF / PDA / HA composite membrane with good hydrophilic performance" (application number 201710829881.1), "A β-FeOOH / PDAus / PVDF composite membrane with superhydrophilicity and its preparation and application" (patent number 202010610909.4), etc.

[0004] The present invention proposes a simple and controllable method to in-situ hydrophilically modify the PVDF surface by regulating the cross-linked structure of melamine, improve the hydrophilicity of the material, and obtain a widely used PVDF composite material. Summary of the Invention

[0005] The present invention proposes to in-situ regulate the formation of the cross-linked structure of melamine polymer on the surface of hydrophobic PVDF nanoparticles, and through a simple hydrothermal treatment process, achieve the hydrophilic modification of PVDF, obtain a hydrophilic PVDF composite material, and improve the hydrophilic performance of PVDF; in addition, metal components can be introduced, the types and amounts of metals can be adjusted, and the formed PVDF metal composite material can be used as a catalyst for catalytic reactions. This modification method has a simple process, is easy to operate, has adjustable structural composition, and has a wide application prospect.

[0006] The preparation method and application of a melamine polymer hydrophilic modified PVDF composite material provided by the present invention adopt the following technical solutions:

[0007] A certain amount of polyvinylidene fluoride (PVDF) nanoparticle powder was ultrasonically dispersed in deionized water, and then a certain amount of organic solvent was added dropwise until a white and uniform PVDF emulsion S1 was formed; a certain amount of melamine was dissolved in an aqueous formaldehyde solution (37 - 40%), or an additional certain amount of metal salt was added to form a clear solution S2; S1 was added to S2, and the mixture was kept in a uniform emulsion state. After stirring in a water bath at 40 - 70°C for 30 minutes, it was transferred to a hydrothermal reaction kettle and reacted at a constant temperature of 100 - 170°C for 6 - 36 hours; after the reaction ended, the solid product was centrifuged, washed with water, washed with alcohol, dried, and ground to obtain a powder product, which was the melamine polymer hydrophilically modified PVDF composite material.

[0008] The PVDF nanoparticle powder is hydrophobic, and the prepared modified PVDF composite materials are all hydrophilic.

[0009] Regarding the formation of the white and uniform PVDF emulsion S1, the uniform emulsion is the key point. During the process of adding the organic solvent dropwise, when a white emulsion is observed, the addition stops, and there is no need to add too much organic solvent.

[0010] Regarding adding S1 to S2 and keeping the mixture in a uniform emulsion state, the uniform emulsion state is the key point. The maximum amount of water in the clear solution S2 is limited by the critical point that does not destroy the uniform emulsion state.

[0011] The organic solvent is a solvent that can dissolve PVDF, including at least one of organic solvents such as dimethylformamide, dimethyl sulfoxide, and dimethylacetamide.

[0012] The metal salt is at least one of nitrates, chlorides, or acetates; the metal is at least one of copper, cobalt, nickel, iron, zinc, zirconium, or cerium.

[0013] In the melamine polymer hydrophilically modified PVDF composite material, the mass percentage content of PVDF is 10% - 70%, the molar percentage of metal to melamine is 0% - 30%; during the material preparation process, the molar ratio of melamine to formaldehyde is 1:4 - 1:10.

[0014] The preparation method is applicable to the hydrophilic modification of other hydrophobic polymer nanoparticles.

[0015] The melamine polymer hydrophilically modified PVDF composite material, the composite material containing metal components is applied to the photocatalytic water splitting hydrogen production reaction and has good activity; it can be extended to other catalytic reaction systems for application.

[0016] The described melamine polymer hydrophilic modified PVDF composite material can be extended and applied to many fields such as oil-water separation treatment, filtration membranes, coatings, etc., improving the hydrophilicity and service performance of the product.

[0017] After being treated by the above method, a PVDF composite structure with significantly improved hydrophilicity is obtained. The modification method mainly has the following characteristics:

[0018] The PVDF nanoparticle raw materials used are hydrophobic and show stronger hydrophilicity after in-situ hydrothermal modification; in the hydrophilic modified PVDF composite structure, the melamine formaldehyde cross-linked polymer existing on the surface is rich in functional groups such as amino groups, facilitating the formation of other functionalized materials; the melamine polymer has a spatial network structure, which is beneficial to loading metal nanoparticles and providing catalytic active components. The method of the present invention is simple and effective, helps to improve the hydrophilic performance of the PVDF composite material, and the material is suitable for applications in many fields such as catalytic reactions, oil-water separation treatment technology, and filter membrane processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the scanning electron microscope image of the melamine polymer hydrophilic modified PVDF copper-based composite material prepared by the present invention;

[0020] Figure 2 It is the contact angle test image of the melamine polymer hydrophilic modified PVDF copper-based composite material prepared by the present invention;

[0021] Figure 3 It is the hydrogen production result of the photocatalytic water decomposition reaction of the melamine polymer hydrophilic modified PVDF copper-based composite material prepared by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0023] Example 1:

[0024] 0.6229 grams of PVDF nanoparticle powder (average particle size about 200 nm) was ultrasonically dispersed in 20 ml of deionized water, and then 10 ml of dimethylformamide (DMF) solvent was added dropwise to form a white homogeneous PVDF emulsion S1; 1.1550 grams of melamine was dissolved in 4.4480 grams of formaldehyde aqueous solution (37 - 40%), and deionized water was added to make the total volume 48 ml to form a clear solution S2; S1 was added to S2 to keep the mixture in a white homogeneous emulsion state. After stirring in a water bath at 50°C for 30 min, it was transferred to a hydrothermal reaction kettle and reacted at 150°C for 20 h. Then, the obtained solid product was centrifuged, washed with water, washed with alcohol, dried, and ground to obtain a powder product, which is the melamine polymer hydrophilic modified PVDF composite material.

[0025] Example 2:

[0026] 1.3658 g of PVDF nanoparticle powder (average particle size about 200 nm) was ultrasonically dispersed in 20 mL of deionized water. Then, 10 mL of DMF was added dropwise until a white homogeneous PVDF emulsion S1 was formed; 1.1550 g of melamine was dissolved in 4.4480 g of formaldehyde aqueous solution (37 - 40%), 0.2743 g of copper acetate was added, and deionized water was added to make the total volume 48 mL to form a clear solution S2; S1 was added to S2 to keep the mixture in a homogeneous emulsion state. After stirring in a water bath at 50 °C for 30 min, it was transferred to a hydrothermal reaction kettle and reacted at 150 °C for 20 h. The obtained solid product was centrifuged, washed with water, washed with alcohol, dried, and ground to obtain a powder product, which was the melamine polymer hydrophilically modified PVDF copper-based composite material.

[0027] Example 3:

[0028] 0.2276 g of PVDF nanoparticle powder (average particle size about 200 nm) was ultrasonically dispersed in 20 mL of deionized water. Then, 10 mL of dimethyl sulfoxide was added dropwise until a white homogeneous PVDF emulsion S1 was formed; 0.0551 g of melamine was dissolved in 0.2098 g of formaldehyde aqueous solution (37 - 40%), and deionized water was added to make the total volume 45 mL to form a clear solution S2; S1 was added to S2 to keep the mixture in a white homogeneous emulsion state. After stirring in a water bath at 40 °C for 30 min, it was transferred to a hydrothermal reaction kettle and reacted at 100 °C for 6 h. The obtained solid product was centrifuged, washed with water, washed with alcohol, dried, and ground to obtain a powder product, which was the melamine polymer hydrophilically modified PVDF composite material.

[0029] Example 4:

[0030] 0.2276 g of PVDF nanoparticle powder (average particle size about 200 nm) was ultrasonically dispersed in 20 mL of deionized water. Then, 8 mL of DMF was added dropwise until a white homogeneous PVDF emulsion S1 was formed; 0.0551 g of melamine was dissolved in 0.3502 g of formaldehyde aqueous solution (37 - 40%), 0.0176 g of copper chloride was added, and deionized water was added to make the total volume 45 mL to form a clear solution S2; S1 was added to S2 to keep the mixture in a homogeneous emulsion state. After stirring in a water bath at 50 °C for 30 min, it was transferred to a hydrothermal reaction kettle and reacted at 150 °C for 20 h. The obtained solid product was centrifuged, washed with water, washed with alcohol, dried, and ground to obtain a powder product, which was the melamine polymer hydrophilically modified PVDF copper-based composite material.

[0031] Example 5:

[0032] 6.1505 g of PVDF nanoparticle powder (average particle size about 400 nm) was ultrasonically dispersed in 50 mL of deionized water, and then 30 mL of DMF was added dropwise to form a white homogeneous PVDF emulsion S1; 0.7425 g of melamine was dissolved in 1.9102 g of aqueous formaldehyde solution (37 - 40%), and deionized water was added to make the total volume 60 mL to form a clear solution S2; S1 was added to S2 to keep the mixture in a white homogeneous emulsion state. After stirring in a water bath at 70 °C for 30 min, it was transferred to a hydrothermal reaction kettle and reacted at 170 °C for 36 h. The obtained solid product was centrifuged, washed with water, washed with alcohol, dried, and ground to obtain a powder product, which was the hydrophilic modified PVDF composite material of melamine polymer.

[0033] Example 6:

[0034] 1.3658 g of PVDF nanoparticle powder (average particle size about 400 nm) was ultrasonically dispersed in 20 mL of deionized water, and then 10 mL of dimethylacetamide was added dropwise to form a white homogeneous PVDF emulsion S1; 1.1550 g of melamine was dissolved in 4.4480 g of aqueous formaldehyde solution (37 - 40%), 0.2514 g of cobalt nitrate was added, and deionized water was added to make the total volume 48 mL to form a clear solution S2; S1 was added to S2 to keep the mixture in a homogeneous emulsion state. After stirring in a water bath at 50 °C for 30 min, it was transferred to a hydrothermal reaction kettle and reacted at 150 °C for 20 h. The obtained solid product was centrifuged, washed with water, washed with alcohol, dried, and ground to obtain a powder product, which was the hydrophilic modified PVDF cobalt-based composite material of melamine polymer.

[0035] Example 7:

[0036] 1.3658 g of PVDF nanoparticle powder (average particle size about 200 nm) was ultrasonically dispersed in 20 mL of deionized water, and then 10 mL of DMF was added dropwise to form a white homogeneous PVDF emulsion S1; 1.1550 g of melamine was dissolved in 4.4480 g of aqueous formaldehyde solution (37 - 40%), 0.2601 g of zinc nitrate was added, and deionized water was added to make the total volume 48 mL to form a clear solution S2; S1 was added to S2 to keep the mixture in a homogeneous emulsion state. After stirring in a water bath at 50 °C for 30 min, it was transferred to a hydrothermal reaction kettle and reacted at 150 °C for 20 h. The obtained solid product was centrifuged, washed with water, washed with alcohol, dried, and ground to obtain a powder product, which was the hydrophilic modified PVDF zinc-based composite material of melamine polymer.

[0037] Example 8:

[0038] 1.3658 g of PVDC nanoparticle powder (average particle size about 200 nm) was ultrasonically dispersed in 20 mL of deionized water. Then, 8 mL of methanol was added dropwise to form a white homogeneous PVDC emulsion S1; 1.1550 g of melamine was dissolved in 4.4480 g of aqueous formaldehyde solution (37 - 40%), and deionized water was added to make the total volume 48 mL to form a clear solution S2; S1 was added to S2 to keep the mixture in the state of a white homogeneous emulsion. After stirring in a water bath at 50 °C for 30 min, it was transferred to a hydrothermal reaction kettle and reacted at 150 °C for 20 h. Then, the obtained solid product was centrifuged, washed with water, washed with alcohol, dried, and ground to obtain a powder product, which was the melamine polymer hydrophilically modified PVDC composite material.

[0039] Example 9:

[0040] The melamine polymer hydrophilically modified PVDF copper-based composite material prepared in Example 2 was used as a catalyst for photocatalytic water splitting reaction. 3 mg of the catalyst and 20 mg of eosin Y were weighed and put into a quartz photoreaction tube, 18 mL of deionized water and 2 mL of triethanolamine were added, and after ultrasonic dispersion, nitrogen was introduced to remove the air in the tube; after the quartz tube was sealed, it was transferred to a photoreaction device with a normal temperature circulating water condenser, and the xenon lamp light source (>420 nm) was turned on for irradiation. The photocatalytic reaction was carried out for 3 h, and gas samples were taken every hour and tested by a gas chromatograph for gas-phase products, indicating the generation of hydrogen.

[0041] The above embodiments are only the preferred embodiments of the present invention and do not limit the patent scope of the present invention. The melamine polymer hydrophilically modified PVDF composite materials mentioned in the present invention are not limited to the above several. Therefore, the above embodiments cannot be regarded as limiting the protection scope of the present invention. Any equivalent structural transformation made by using the content of the specification of the present invention under the inventive concept of the present invention, or direct / indirect application in other related technical fields is included in the patent protection scope of the present invention.

Claims

1. A preparation method and application of a hydrophilic modified PVDF composite material of melamine polymer, characterized in that, It includes the following steps: Ultrasonically disperse a certain amount of polyvinylidene fluoride (PVDF) nanoparticle powder in deionized water, and then dropwise add a certain amount of organic solvent until a white homogeneous PVDF emulsion S1 is formed; Dissolve a certain amount of melamine in an aqueous formaldehyde solution (37 - 40%), or additionally add a certain amount of metal salt to form a clear solution S2; Add S1 to S2, keep the mixture in a homogeneous emulsion state, stir in a water bath at 40 - 70 °C for 30 minutes, then transfer it to a hydrothermal reaction kettle and react at a constant temperature of 100 - 170 °C for 6 - 36 hours; After the reaction is completed, centrifuge the solid product, wash it with water, wash it with alcohol, dry it, and grind it to obtain a powder product, which is the melamine polymer hydrophilic modified PVDF composite material.

2. The preparation method and application of a melamine polymer hydrophilically modified PVDF composite material according to claim 1, characterized in that, The PVDF nanoparticle powder is hydrophobic, and the prepared modified PVDF composite materials are all hydrophilic.

3. The preparation method and application of a melamine polymer hydrophilically modified PVDF composite material according to claim 1, characterized in that, Regarding the formation of the white homogeneous PVDF emulsion S1, the homogeneous emulsion therein is the key point. During the process of dropwise adding the organic solvent, stop adding when observing the formation of a white emulsion, and there is no need to add too much organic solvent.

4. The preparation method and application of a melamine polymer hydrophilic modified PVDF composite material according to claim 1, characterized in that, Regarding adding S1 to S2 to keep the mixture in a homogeneous emulsion state, the homogeneous emulsion state therein is the key point. The maximum amount of water used in the clear solution S2 is limited by the critical point that does not destroy the homogeneous emulsion state.

5. The preparation method and application of a melamine polymer hydrophilic modified PVDF composite material according to claim 1, characterized in that, The organic solvent is a solvent capable of dissolving PVDF, including at least one of organic solvents such as dimethylformamide, dimethyl sulfoxide, and dimethylacetamide.

6. The preparation method and application of a melamine polymer hydrophilic modified PVDF composite material according to claim 1, characterized in that, The metal salt is at least one of nitrates, chlorides, or acetates; the metal is at least one of copper, cobalt, nickel, iron, zinc, zirconium, or cerium.

7. The preparation method and application of a melamine polymer hydrophilically modified PVDF composite material according to claim 1, characterized in that, In the melamine polymer hydrophilic modified PVDF composite material, the mass percentage content of PVDF is 10% - 70%, and the molar percentage of metal to melamine is 0% - 30%; During the material preparation process, the molar ratio of melamine to formaldehyde is 1:4 - 1:

10.

8. The preparation method and application of a melamine polymer hydrophilic modified PVDF composite material according to claim 1, characterized in that, The preparation method is applicable to the hydrophilic modification of other hydrophobic polymer nanoparticles.

9. The preparation method and application of a melamine polymer hydrophilic modified PVDF composite material according to claim 1, characterized in that, Regarding the melamine polymer hydrophilic modified PVDF composite material, the composite material containing metal components has good activity when applied to the photocatalytic water splitting hydrogen production reaction; it can be extended to other catalytic reaction systems for application.

10. The preparation method and application of a melamine polymer hydrophilically modified PVDF composite material according to claim 1, characterized in that, The melamine polymer hydrophilic modified PVDF composite material can be extended for application in many fields such as oil-water separation treatment, filtration membranes, coatings, etc., to improve the hydrophilicity and service performance of the products.

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