Super-hydrophobic composite nanofiber membrane, and preparation method and application thereof

Abstract

The application belongs to the technical field of nanofiber membrane preparation, and particularly relates to a super-hydrophobic composite nanofiber membrane and a preparation method and application thereof. The method comprises the following steps: placing raw material polyaniline / polyimide (PANI / PI) nanofiber membrane in a dopamine aqueous solution, constructing a PANI / PI micro-nano structure through polyaniline, covering the PANI / PI with a layer of polydopamine, and reacting groups of the polydopamine with perfluoroacyl chloride to graft a fluorine-containing substance with low surface free energy, so as to prepare a PFAC / PDA / PANI / PI composite nanofiber membrane. The method is simple in operation, wide in application range, and can be used to prepare the super-hydrophobic nanofiber membrane. The prepared membrane has the advantages of good hydrophobic performance, good salt ion interception effect, and wide application range.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nanofiber membrane preparation, and particularly relates to a super-hydrophobic composite nanofiber membrane and a preparation method and application thereof. BACKGROUND

[0002] Super-hydrophobic technology is a new technology that can make the surface of a material have special properties, and can make the material have the functions of waterproofing, ice prevention, corrosion prevention and self-cleaning. Some application prospects of super-hydrophobic materials are listed, such as a fabric with super-hydrophobic function can play a role in waterproofing and stain prevention, thereby improving the utilization rate of the fabric ] ; a metal material with super-hydrophobic function can play a role in corrosion prevention, thereby improving the service life of the metal material; a ship with a super-hydrophobic coating can play a role in drag reduction, thereby reducing energy consumption; a cable with super-hydrophobic function can prevent icing, which can reduce the investment of manpower and material resources; super-hydrophobic materials can also be used in some special occasions, such as oil-water separation, anti-microbial adhesion, etc.

[0003] At present, the materials commonly used for preparing super-hydrophobic membranes mainly include polyvinylidene fluoride (PVDF), polystyrene (PS) and polyurethane (PU) polymers, which have high requirements for the types of materials, and the existing super-hydrophobic membranes have poor hydrophobicity and poor salt ion interception effect. Therefore, how to prepare a super-hydrophobic membrane which not only has good hydrophobicity and good salt ion interception effect, but also has a wide range of application scope of the preparation method has become a difficult problem. SUMMARY

[0004] The purpose of the present application is to solve the problems of the prior art, and to provide a super-hydrophobic composite nanofiber membrane and a preparation method and application thereof. The following technical solutions are used:

[0005] In one aspect of the present application, a preparation method of a super-hydrophobic composite nanofiber membrane is provided, which comprises the following steps:

[0006] (1) The polyaniline / polyimide (PANI / PI) nanofiber membrane is placed in a dopamine aqueous solution, then glucose is added, and the reaction is carried out under ultrasonic conditions. After the reaction is completed, a PDA / PANI / PI nanofiber membrane is obtained.

[0007] (2) The PDA / PANI / PI nanofiber membrane is placed in a 1 wt.% 1H,1H,2H,2H-perfluoroacyl chloride (PFAC) solution, and the reaction is carried out under ultrasonic conditions. After the reaction is completed, the PDA / PANI / PI nanofiber membrane is washed and vacuum dried, and finally a PFAC / PDA / PANI / PI composite nanofiber membrane is obtained.

[0008] The application places raw material polyaniline / polyimide (PANI / PI) nanofiber membrane in dopamine aqueous solution, constructs PANI / PI micro-nano structure through polyaniline, covers polyaniline / PI with a layer of polydopamine, and reacts amino and hydroxyl in polydopamine with perfluoroacyl chloride to graft low-surface-energy fluorine-containing substances, so that the surface of PDA / PANI / PI nanofiber is covered with a layer of fluorine-containing hydrophobic substances, thereby preparing PFAC / PDA / PANI / PI composite nanofiber membrane. The method for preparing super-hydrophobic nanofiber membrane is simple in operation, wide in application range, and the prepared membrane has the advantages of good hydrophobic performance, good salt ion interception effect, and wide application range.

[0009] The perfluoroacyl chloride in the above step (2) is at least one of 11H-perfluoroundecanoyl chloride, perfluorooctanoyl chloride, perfluoroheptanoyl chloride, perfluorohexanoyl chloride, and heptafluorobutyryl chloride.

[0010] As a further preferred embodiment, the above polyaniline / polyimide (PANI / PI) nanofiber membrane is obtained by the following steps:

[0011] (1) Diphenyl tetracarboxylic dianhydride and ether diamine are added to DMAc (N,N-dimethylacetamide), stirred at 200 rpm-1800 rpm, and reacted at-5 ℃-5 ℃ for 5-14 hours to obtain a polyamide acid (PAA) solution, then the prepared PAA solution is made into a PAA nanofiber membrane by electrospinning, and finally a polyimide (PI) nanofiber membrane is prepared by thermal imidization;

[0012] (2) The PI nanofiber membrane is put into an aniline-containing sulfuric acid solution, and in-situ polymerization is carried out at a temperature of-2 ℃-5 ℃ to obtain a polyaniline / polyimide (PANI / PI) nanofiber membrane, after washing the residual with water, drying in a 60 ℃ vacuum oven for 5-7 hours to obtain a PANI / PI nanofiber membrane with micro-nano structure. The intrinsic viscosity of the polyamide acid (PAA) solution in the above step is 1.5 dl / g-4.5 dl / g; when the intrinsic viscosity is less than 1.5, the polyamide acid (PAA) has a small molecular weight, thereby reducing the mechanical and thermal properties of the PI nanofiber membrane, but when the intrinsic viscosity is greater than 4.5, the PAA nanofiber membrane is difficult to prepare.

[0013] The present application prepares PANI / PI nanofiber membrane with micro-nano structure through the base film preparation stage and the micro-nano structure construction stage. In the base film preparation stage, using biphenyl tetracarboxylic dianhydride and ether diamine as raw materials, under the condition of strong mechanical stirring of 200 rpm-1800 rpm, at-5℃-5℃ for 5-14 hours, the polycondensation reaction is an exothermic reaction, and low temperature is conducive to the reaction to the direction of polyamide acid, and high molecular weight polyimide is easily obtained. After obtaining the polyamide acid solution, PI nanofiber membrane is prepared by electrospinning and thermal imidization; then in the micro-nano structure construction stage, the PI nanofiber membrane is put into the sulfuric acid solution containing aniline, and in-situ polymerization is carried out to obtain the PANI / PI nanofiber membrane with micro-nano structure.

[0014] As a further preferred embodiment, the biphenyl tetracarboxylic dianhydride and the ether diamine are 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA) and 4,4-diamino diphenyl ether (ODA) respectively. Using 3,3',4,4'-biphenyl tetracarboxylic dianhydride and 4,4-diamino diphenyl ether as raw materials, the reactivity is moderate, thereby being conducive to the preparation of high molecular weight polymer.

[0015] As a further preferred embodiment, the concentration of the sulfuric acid solution is 0.15 mol / L-1.2 mol / L. When the concentration of the sulfuric acid solution is less than 0.15 mol / L or greater than 1.2 mol / L, uniform polyaniline cannot be grown on the PI nanofiber membrane.

[0016] As a further preferred embodiment, the electrospinning parameters include: the applied voltage is about 5 Kv-25 Kv, the receiving distance is about 8 cm-25 cm, and the temperature is 20℃-25℃. When the applied voltage is less than 5 Kv and greater than 25 Kv, the quality of the prepared nanofiber membrane will be affected, and when the receiving distance is outside the range of 8 cm-25 cm, the collection efficiency of the PI nanofiber membrane will be affected. When the temperature is lower than 20℃, the solvent volatilization will be affected, and when the temperature is higher than 25℃, the PAA molecules will be degraded.

[0017] As a further preferred embodiment, the ratio of the use amount of the dopamine aqueous solution to the glucose is 10:1 in molar ratio. When the ratio is greater than or less than 10:1, the formation of polydopamine will be affected.

[0018] As a further preferred embodiment, the concentration of the dopamine aqueous solution is 0.1 mol / L-0.5 mol / L. When the concentration is less than 0.1 mol / L or greater than 0.5 mol / L, the growth speed and thickness of the polydopamine will be affected, which is not conducive to the subsequent process.

[0019] As a further preferred embodiment, the solvent used for washing in step (2) is ethanol, the temperature for vacuum drying is 60 DEG C, and the time is 5 h.

[0020] In another aspect of the present application, a super-hydrophobic composite nanofiber membrane is also provided, which is prepared by the above method, and has a super-hydrophobic structure and is attached with super-hydrophobic substances, so that the hydrophobic property, oil-water separation effect and salt ion interception effect are further improved.

[0021] The present application has the advantages that: the present application provides a super-hydrophobic composite nanofiber membrane, which can be applied in the treatment of industrial wastewater. The preparation method provided by the present application is widely applicable, and the prepared super-hydrophobic membrane not only has good super-hydrophobicity, but also has multiple super-hydrophobic properties (such as self-cleaning, corrosion resistance, etc.); it also has good oil-water separation effect and high salt interception rate, avoiding the shortcomings of the prior art, such as narrow application range, unsatisfactory hydrophobic effect, and limited use range. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The contact angles of different nanofibers are shown: 1 is the contact angle of PI 124 o , 2 is the contact angle of PANI / PI 26 o , 3 is the contact angle of PDA / PANI / PI 110 o , 4 is the contact angle of PFAC / PDA / PANI / PI 158 o ;

[0023] Figure 2 The contact angle is 158 o super-hydrophobic PI nanofiber membrane oil-water separation diagram. DETAILED DESCRIPTION

[0024] The concept, specific structure and technical effects of the present application will be described clearly and completely in combination with the embodiments and drawings, so as to fully understand the purpose, scheme and effect of the present application.

[0025] Example 1

[0026] A super-hydrophobic composite nanofiber membrane, the preparation method thereof comprising the following steps:

[0027] (1) Base film preparation stage: polyamide acid (PAA) is synthesized by polycondensation reaction using 4,4-diaminodiphenyl ether (ODA) and 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA) as raw materials, and adding in a proportion of 1:1; then PAA nanofiber membrane is prepared by electrospinning using a PAA solution with a solid content of 12% as raw material; a syringe containing 5 mL of PAA solution is fixed on a self-assembled electrospinning device, the working voltage is about 15 kV, the working distance between the needle tip and the collector is about 10 cm, and the temperature is room temperature; the PAA nanofiber membrane is heat imidized at 320°C to obtain a PI nanofiber membrane. (2) Micro-nano structure construction stage: first, the PI nanofiber membrane is activated by immersing it in a 1% sodium dodecyl sulfate solution for 40 min, then the residual liquid is washed off with deionized water, then the activated PI membrane is put into 25 mL of sulfuric acid (0.5 M) containing 60 μL of aniline, then 0.12 g of ammonium persulfate is dissolved in 25 mL of sulfuric acid (0.5 M), and slowly added to the above solution, and after in-situ polymerization for 2 h, a PANI / PI nanofiber membrane is obtained, which is washed with distilled water to remove the residual material, and then dried in a vacuum oven at 60°C for 5 hours, thereby obtaining a PANI / PI nanofiber membrane with micro-nano structure;

[0028] (3) The PANI / PI nanofiber composite membrane is put into a 0.25 mol / L dopamine aqueous solution, and a small amount of glucose is added (the molar ratio of dopamine to glucose is 10:1), and the reaction is carried out under ultrasonic conditions for 1 h to obtain a PDA / PANI / PI nanofiber composite membrane. The PDA / PANI / PI nanofiber composite membrane is put into a 0.2 wt.% 11H-perfluoroundecanoyl chloride (PFAC) solution, and the reaction is carried out under ultrasonic conditions for 1 h, then the residual material is washed off with ethanol, and then dried in a vacuum oven at 60°C for 5 h, to finally obtain a PFAC / PDA / PANI / PI composite nanofiber membrane, and the contact angle is 145 o The PI nanofiber membrane is used for oil-water separation, and a small amount of oil is still not separated completely.

[0029] Example 2

[0030] A super-hydrophobic composite nanofiber membrane, and a preparation method thereof, the method comprising the following steps:

[0031] (1) Base film preparation stage: polyamide acid (PAA) is synthesized by polycondensation reaction using 4,4-diaminodiphenyl ether (ODA) and 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA) as raw materials, and adding them in a ratio of 1:1. Then, PAA nanofiber membrane is prepared by electrospinning using a PAA solution with a solid content of 12% as raw material. In general, a syringe containing 5 mL of PAA solution is fixed on a self-assembled electrospinning device, the working voltage is about 15 kV, the working distance between the needle tip and the collector is about 10 cm, and the temperature is room temperature. The PAA nanofiber membrane is heat imidized at 320°C to obtain a PI nanofiber membrane. (2) Micro-nano structure construction stage: first, the PI nanofiber membrane is activated by immersing it in a 1% sodium dodecyl sulfate solution for 40 min, then washing the residual liquid with deionized water, and then immersing the activated PI membrane into 25 mL of sulfuric acid (0.5 M) containing 60 μL of aniline. Then, 0.12 g of ammonium persulfate is dissolved in 25 mL of sulfuric acid (0.5 M), and slowly added to the above solution. After in-situ polymerization for 2 h, a PANI / PI nanofiber membrane is obtained. After washing the residual liquid with distilled water, the PANI / PI nanofiber membrane with micro-nano structure is obtained by drying in a vacuum oven at 60°C for 5 hours.

[0032] (3) The PANI / PI nanofiber composite membrane is immersed into a 0.25 mol / L dopamine aqueous solution, and a small amount of glucose is added (the molar ratio of dopamine to glucose is 10:1). After reacting for 1 h under ultrasonic conditions, a PDA / PANI / PI nanofiber composite membrane is prepared. The PDA / PANI / PI nanofiber composite membrane is immersed into a 0.5 wt% 11H-perfluoroundecanoyl chloride (PFAC) solution, and reacts for 1 h under ultrasonic conditions. After washing the residual liquid with ethanol, the PFAC / PDA / PANI / PI composite nanofiber membrane is obtained by drying in a vacuum oven at 60°C for 5 h. The contact angle is 150 o Superhydrophobic PI nanofiber membrane. The PI nanofiber membrane is used for oil-water separation, and the oil and water are basically separated completely.

[0033] Example 3

[0034] A superhydrophobic composite nanofiber membrane, and a preparation method thereof, includes the following steps:

[0035] (1) Base film preparation stage: polyamide acid (PAA) is synthesized by polycondensation reaction using 4,4-diaminodiphenyl ether (ODA) and 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA) as raw materials in a proportion of 1:1, and then PAA nanofiber membrane is prepared by electrospinning using a PAA solution with a solid content of 12% as raw material. In general, a syringe containing 5 mL of PAA solution is fixed on a self-assembled electrospinning device, the working voltage is about 15 kV, the working distance between the needle tip and the collector is about 10 cm, and the temperature is room temperature. The PAA nanofiber membrane is heat imidized at 320°C to obtain a PI nanofiber membrane;

[0036] (2) Micro-nano structure construction stage: the PI nanofiber membrane is first activated by immersing it in a 1% sodium dodecyl sulfate solution for 40 min, then washed with deionized water to remove residual liquid, and then the activated PI membrane is placed in 25 mL of sulfuric acid (0.5 M) containing 60 μL of aniline, and then 0.12 g of ammonium persulfate is dissolved in 25 mL of sulfuric acid (0.5 M) and slowly added to the above solution. After in-situ polymerization for 2 h, a PANI / PI nanofiber membrane is obtained, which is washed with distilled water to remove residual substances and dried in a vacuum oven at 60°C for 5 hours, thereby obtaining a PANI / PI nanofiber membrane with micro-nano structure;

[0037] (3) The PANI / PI nanofiber composite membrane is placed in a 0.25 mol / L dopamine aqueous solution, and a small amount of glucose is added (the molar ratio of dopamine to glucose is 10:1), and the reaction is carried out under ultrasonic conditions for 1 h to obtain a PDA / PANI / PI nanofiber composite membrane. The PDA / PANI / PI nanofiber composite membrane is placed in a 0.8 wt% 11H-perfluoroundecanoyl chloride (PFAC) solution and reacted under ultrasonic conditions for 1 h, then washed with ethanol to remove residual substances, and dried in a vacuum oven at 60°C for 5 h to finally obtain a PFAC / PDA / PANI / PI nanofiber composite membrane with a contact angle of 154 o Superhydrophobic PI nanofiber membrane. The PI nanofiber membrane is used for oil-water separation, and the oil-water separation is relatively clean.

[0038] Example 4

[0039] A superhydrophobic composite nanofiber membrane, the preparation method thereof comprising the following steps:

[0040] (1) Base film preparation stage: polyamic acid (PAA) is synthesized by polycondensation reaction using 4,4-diaminodiphenyl ether (ODA) and 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA) as raw materials, and adding them in a ratio of 1:1. Then, PAA nanofiber membrane is prepared by electrospinning using a PAA solution with a solid content of 12% as raw material. In general, a syringe containing 5 mL of PAA solution is fixed on a self-assembled electrospinning device, the working voltage is about 15 kV, the working distance between the needle tip and the collector is about 10 cm, and the temperature is room temperature. The PAA nanofiber membrane is heat imidized at 320°C to obtain a PI nanofiber membrane.

[0041] (2) Micro-nano structure construction stage: first, the PI nanofiber membrane is activated by immersing it in a 1% sodium dodecyl sulfate solution for 40 min, then washed with deionized water to remove residual liquid, then the activated PI membrane is put into 25 mL of sulfuric acid (0.5 M) containing 60 μL of aniline, then 0.12 g of ammonium persulfate is dissolved in 25 mL of sulfuric acid (0.5 M), slowly added to the above solution, and then in-situ polymerization for 2 h to obtain a PANI / PI nanofiber membrane. After washing with distilled water to remove the residue, the PANI / PI nanofiber membrane with micro-nano structure is obtained by drying in a vacuum oven at 60°C for 5 hours.

[0042] (3) The PANI / PI nanofiber composite membrane is put into a 0.25 mol / L dopamine aqueous solution, and a small amount of glucose is added (the molar ratio of dopamine to glucose is 10:1), and the PDA / PANI / PI nanofiber composite membrane is prepared by reacting for 1 h under ultrasonic conditions. The PDA / PANI / PI nanofiber composite membrane is put into a 1 wt% 11H-perfluoroundecanoyl chloride (PFAC) solution, and after reacting for 1 h under ultrasonic conditions, the residue is washed with ethanol, and then dried in a vacuum oven at 60°C for 5 h to obtain the PFAC / PDA / PANI / PI nanofiber composite membrane, and the contact angle is 158 o Super-hydrophobic PI nanofiber membrane. The PI nanofiber membrane is used for oil-water separation, and the oil-water separation is very clean.

[0043] Although the description of the present application has been quite detailed and particularly described with respect to several described embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, but should be considered to be a broad interpretation of the prior art by reference to the appended claims, so as to effectively encompass the intended scope of the present application. Furthermore, the present application is described above in embodiments that the inventors can foresee, and the purpose is to provide a useful description, and non-essential modifications to the present application that have not yet been foreseen can still represent equivalent modifications of the present application.

Claims

1. A method for preparing a superhydrophobic composite nanofiber membrane, characterized by, The method comprises the following steps: (1) placing a polyaniline / polyimide (PANI / PI) nanofiber membrane in a dopamine aqueous solution, then adding glucose, and reacting under ultrasonic conditions to obtain a PDA / PANI / PI nanofiber membrane after the reaction is completed; (2) placing the PDA / PANI / PI nanofiber membrane in a 1 wt.% 1H,1H,2H,2H-perfluoroacyl chloride (PFAC) solution, and reacting under ultrasonic conditions, and then washing, vacuum drying, and finally obtaining a PFAC / PDA / PANI / PI composite nanofiber membrane after the reaction is completed; The dopamine aqueous solution and the glucose are used in a molar ratio of 10:1, and the dopamine aqueous solution has a concentration of 0.1 mol / L-0.5 mol / L. The polyaniline / polyimide (PANI / PI) nanofiber membrane is obtained by the following steps: S1: adding diphenyl tetracarboxylic dianhydride and ether diamine into DMAc (N,N-dimethylacetamide), stirring at 200 rpm-1800 rpm, and reacting at-5 ℃-5 ℃ for 5-14 hours to obtain a polyamic acid (PAA) solution, then electrospinning the obtained PAA solution into a PAA nanofiber membrane, and finally obtaining a polyimide (PI) nanofiber membrane through thermal imidization; the polyamic acid (PAA) solution has a characteristic viscosity of 1.5 dl / g-4.5 dl / g; S2: placing the PI nanofiber membrane into an aniline-containing sulfuric acid solution, and performing in-situ polymerization at a temperature of-2 ℃-5 ℃ to obtain a polyaniline / polyimide (PANI / PI) nanofiber membrane, then washing the residual material with water, and drying in a vacuum oven at 60 ℃ for 5-7 hours to obtain a PANI / PI nanofiber membrane with a micro-nano structure.

2. The production method according to claim 1, characterized by, The diphenyl tetracarboxylic dianhydride and the ether diamine are 3,3',4,4'-diphenyl tetracarboxylic dianhydride (BPDA) and 4,4-diamino diphenyl ether (ODA), respectively.

3. The preparation method according to claim 1, characterized in that, The concentration of the sulfuric acid solution is 0.15 mol / L-1.2 mol / L.

4. The production method according to claim 1, characterized by, The electrospinning parameters include an applied voltage of 5 Kv-25 Kv, a receiving distance of 8 cm-25 cm, and a temperature of 20 ℃-25 ℃.

5. The preparation method according to claim 1, characterized in that, The solvent used for washing in step (2) is ethanol, the vacuum drying temperature is 60 ℃, and the time is 5 h.

6. A superhydrophobic composite nanofiber membrane, characterized by, Obtained by the preparation method of any one of claims 1-5.

7. Use of the super-hydrophobic composite nanofiber membrane of claim 6 in treating industrial wastewater.

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