CN100577271C - A kind of preparation method of organic-inorganic hybrid anion exchange membrane based on copolymer - Google Patents

Abstract

The invention discloses a preparation method for preparing the exchange membrane based on copolymer organic-inorganic hybrid anion. The preparation method is that a polymer that contains halogen methyl and alkoxy silicon group is firstly synthesized, the polymer is dissolved into the mixed solvent to form the solution, and is added or not added with small molecule alkoxy silane crosslinking agent to obtain the sol-gel precursor body which is added with tertiary amine, catalyst, water and ethanol for reacting under the magnetic stirring to obtain the sol-gel solution; the sol-gel solution after being concentrated is coated on the base to form the membrane; the membrane is dried and solidified to obtain the exchange membrane of organic-inorganic hybrid anion. The exchange membrane of organic-inorganic hybrid anion prepared by adopting the method of the invention has the advantages of high exchange capacity of ion, good mechanical property, excellent compatibility between inorganic silicon oxide component and organic component in the membrane, excellent heat stability, oxidation resistance, alkali resistance and high application potential to the battery of alkaline fuel.

Description

A kind of preparation method of organic-inorganic hybrid anion exchange membrane based on copolymer

Technical field:

The invention belongs to the field of membrane technology, in particular to a method for preparing an organic-inorganic hybrid anion exchange membrane by a sol-gel method.

Background technique:

Chinese Patent Application No. 200410065737.8 discloses a method for preparing an organic-inorganic hybrid anion exchange membrane. The benzyl bromide group on the benzyl brominated polyphenylene ether (BPPO) chain is grafted with aminohydrocarbyl silane, and is also combined with The tertiary amine reacts to form a quaternary ammonium group to obtain a positively charged sol-gel reaction precursor, and then performs a sol-gel reaction with unreacted aminoalkylsilane to prepare a hybrid anion exchange membrane. The hybrid anion exchange membrane obtained by the method has good compatibility of organic-inorganic components, and the method is simple, but the source of the raw material is single, and the properties of the modified membrane are largely affected by the properties of the original polymer material BPPO.

Chinese Patent Application No. 200610097187.7 proposes a method for preparing an organic-inorganic hybrid anion exchange membrane, which involves mixing a positively charged alkoxy functionalized macromolecular precursor and a positively charged small molecular alkane in a certain molar ratio Oxysilane, and then add one or two small molecular alkoxysilanes to obtain a sol-gel mixed precursor. The mixed precursor is subjected to sol-gel reaction, and the hybrid anion exchange membrane is obtained after the coating film is dried. Since the raw material used to prepare the positively charged alkoxy functionalized macromolecular precursor is aliphatic polymer, the stability is not as good as that of aromatic polymer; the ion exchange capacity of the membrane is not high, and the anions in the membrane are formed by Cl ^- After the OH ^- type is converted into the OH-type, the stability of the membrane becomes poor, which limits the application in alkaline fuel cells.

"Journal of Membrane Science" (Journal of Membrane Science, 218 (2003) 147-163) reported that by irradiating perfluorocopolymers, grafting chloromethyl styrene, and then quaternizing chloromethyl, An anion exchange membrane is obtained. The membrane obtained by this method has good stability and high OH ^- conductivity of the membrane, but the selected perfluorocopolymer is expensive, the irradiation conditions are not easy to control, and the ion exchange capacity of the obtained membrane is low.

"Journal of Applied Polymer Science" (Journal of Applied Polymer Science, 100 (2006) 2248-2251) reported the preparation of a copolymer of 4-vinylpyridine and styrene, and after the quaternization reaction of the copolymer with 1-bromooctane , coated on a non-woven fabric, and dried to obtain an anion exchange membrane. Since the pyridine-type quaternary ammonium salt is unstable in an alkaline environment, the pyridine-type quaternary ammonium salt is more likely to degrade after heating up, so the stability of the obtained membrane is not good. The application feasibility of direct methanol fuel cell is not high.

Invention content:

The purpose of the present invention is to provide a method for preparing an organic-inorganic hybrid anion exchange membrane, so as to overcome the above-mentioned defects of the prior art.

The technical scheme of the present invention is as follows: first synthesize a polymer containing halomethyl and alkoxy silicon groups, dissolve in a mixed solvent to form a solution with a concentration of 0.04-0.13 grams/milliliter (g/ml), and then select One or two small molecule alkoxysilanes are used as a crosslinking agent; it is characterized in that: adding/not adding the crosslinking agent to the polymer solution to obtain a sol-gel precursor; - Add tertiary amine, catalyst and water to the gel precursor, react for 12-64h (hours) under magnetic stirring, add ethanol to the solution before or within 4 hours after the reaction, and obtain a sol-gel solution after the reaction; sol- The gel solution is volatilized until the volume is reduced to 40%-64% of the original, and then applied on the substrate to form a film, and the organic-inorganic hybrid anion exchange membrane is obtained after the film is dried and solidified;

The mixed solvent is composed of a type A solvent and a type B solvent, wherein the type A solvent is toluene, chloroform or chlorobenzene, and the type B solvent is N,N-dimethylformamide (DMF) or N-methylpyrrolidone; The volume fraction of Class A solvent in the mixed solvent is 17%-52%;

The chemical formula of the small molecule alkoxysilane can be expressed as [R] _4-q Si(R3) _q , wherein R3 represents an alkyl or aryl group containing 0-1 nitrogen and 1-7 carbons, and the value of q is 0 or 1;

The mass ratio of the polymer to the crosslinking agent is 1:0-0.63;

The mass ratio of the polymer contained in the sol-gel precursor to tertiary amine, catalyst, and water is 1: 0.16-1.77: 0-0.015: 0.37-1.73, and the volume of the sol-gel precursor to ethanol The ratio is 1:0.14-0.53;

The tertiary amine is selected from trimethylamine, triethylamine or tripropylamine;

The catalyst is selected from ammonia, sodium formate, sodium acetate, sodium hydroxide, potassium hydroxide;

The substrate refers to the inorganic matrix _Al2O3 porous ceramics _{, Al2O3} microfiltration or ultrafiltration membrane, glass plate, aluminum plate or stainless steel plate, _or organic matrix polyester cloth, nylon cloth, glass fiber cloth, nylon cloth, Woven cloth, PTFE board or PVC board;

The method of coating film comprises scraping film, spraying, dipping, drool or coating;

The drying and curing of the film is: drying the film at room temperature until the film is completely cured; then continue to dry at room temperature for 8-14 days or increase the temperature from room temperature to 75-105 °C at a rate of 2.5-6 °C/h, and keep warm for 2.5- 7h.

The preparation process of the polymer containing halomethyl and alkoxy silicon groups is as follows: select a monomer M containing double bonds and alkoxy silicon groups, a monomer M containing double bonds and halomethyl groups Body N, in molar ratio M:N=1:0.42-2.34 mix two monomers; solvent by volume ratio: the volume sum of the two monomers=3.7-8.3 Add A type solvent to the two monomer mixtures ; Under the protection of an inert gas, the molar ratio is the free radical initiator: the sum of the two monomers = 0.4%-1.2% Add dibenzoyl peroxide (BPO) or azodiiso Butyronitrile (AIBN), reacted at 60-80°C for 12-48h, the obtained polymer solution was concentrated under reduced pressure to remove 0-66% A-type solvent, then purified and concentrated by n-hexane or petroleum ether precipitation-A-type solvent dissolution After the polymer solution 2-6 times.

The monomer M containing a double bond and an alkoxy silicon group can be expressed as XR1Si(R) ₃ ; wherein R1 represents an alkyl or aryl group containing 1-7 carbon atoms, and R represents an alkyl or aryl group containing 1 Or an alkoxy group with 2 carbons, X represents a vinyl or methacrylic group.

The chemical formula of the monomer N containing a double bond and a halomethyl group can be expressed as YZR2; wherein Y represents a halomethyl group, Z represents a vinyl or styryl group, and R2 represents an alkyl group containing 0-4 carbons.

The method of the present invention takes the step of first synthesizing a polymer containing halomethyl and alkoxysilane groups, after the polymer is mixed with a small molecule alkoxysilane, the halomethyl contained in the polymer undergoes a quaternization reaction, The alkoxy silicon group contained can carry out sol-gel reaction with small molecule alkoxysilane to obtain a sol-gel solution; the sol-gel solution can form a film by itself, or can be prepared as a support membrane. The method of the present invention is the same as that reported in Chinese Patent Application No. 200410065737.8 in which aminoalkyl silane is grafted on the polymer compound BPPO chain, followed by quaternization, and finally a sol-gel reaction is carried out with unreacted aminoalkyl silane to obtain a hybrid Compared with the method of anion exchange membrane, the raw material source that the present invention adopts is extensive, by changing the kind of copolymer and quaternization degree, can obtain the membrane of different properties; A positively charged alkoxy functionalized macromolecular precursor and a positively charged small molecule alkoxysilane, and then add one or two small molecule alkoxysilanes, and perform a sol-gel reaction to obtain a hybrid Compared with the method of anion exchange membrane, the present invention can utilize the aromatic copolymer containing functional group to prepare a membrane with higher stability, and by increasing the degree of quaternization and the content of halomethyl group in the copolymer, the Membrane with high ion exchange capacity; and "Journal of Membrane Science" (Journal of Membrane Science, 218 (2003) 147-163) reported irradiating with perfluorocopolymer, grafting chloromethyl styrene and then performing quarterly Ammonification reaction, the method that obtains anion-exchange membrane is compared, can adopt extensive, cheap raw material in the inventive method, and preparation method is simple and easy, and the membrane that obtains has higher ion-exchange capacity; (Journal of Applied PolymerScience, 100 (2006) 2248-2251) reported that the copolymer of 4-vinylpyridine and styrene was first prepared, and the copolymer was quaternized and then coated on the non-woven fabric, and anion was obtained after drying. Compared with the method of exchanging membranes, the method of the present invention can prepare dense and high alkali-resistant membranes, the membranes have high oxidation resistance, and have higher application potential in alkaline fuel cells.

Detailed ways:

The preparation method of the organic-inorganic hybrid anion exchange membrane of the present invention will be further described in detail through examples below.

Embodiment 1: Copolymer (VBC/KH-570)-SiO ₂ Preparation of hybrid anion exchange membrane

Preparation of raw materials: (1) Water removal: Soak toluene and n-hexane in molecular sieve for two days; (2) Recrystallization of azobisisobutyronitrile (AIBN): 10 grams of AIBN dissolved in 100ml of methanol at 35°C (3) collection of trimethylamine: add 100ml of saturated trimethylamine aqueous solution in a single-necked round-bottomed flask, Heating the solution at a rate of 10°C/h from 30°C to 80°C and keeping it at 80°C for 2h, using 130ml N,N-dimethylformamide (DMF) to collect the trimethylamine gas released from the trimethylamine aqueous solution, to obtain Trimethylamine DMF solution with a concentration of 3.27 mol/liter (mol/L). Then proceed to the following steps:

1. Preparation of p-chloromethylstyrene (VBC)/trimethoxysilyl propyl methacrylate (KH-570) copolymer: adopt a 250ml round bottom flask equipped with a reflux condenser and have a nitrogen inlet and outlet, add 6.9ml of VBC, 11.8ml of KH-570 and 70ml of toluene were heated to 70°C under the protection of nitrogen, and 0.131g of AIBN was added, and stirred and reacted for 24h under the same environment to obtain a polymer solution. The polymer was repeatedly purified four times by n-hexane precipitation-toluene dissolution, and the purified polymer was dissolved in toluene to form a 0.21 g/ml solution. Take 2ml of polymer solution and coat it on a tetrafluoroethylene plate, place it in a vacuum environment at room temperature for a week, scrape off the polymer with a scalpel, and perform NMR test. The result shows that the mole percentage of VBC in the copolymer is 54.7%.

2. Preparation of sol-gel solution: pipette 7.20ml of polymer solution into a conical flask, add 13.92ml of DMF, mix evenly, add 0.38ml of phenyltriethoxysilane (EPh), add 1.73ml under stirring Trimethylamine and 0.82ml of water were reacted at room temperature for 0.5h, then 11ml of ethanol was added, and stirring was continued for 48h at room temperature to obtain a sol-gel solution.

3. Preparation of the hybrid membrane: transfer the sol-gel solution to a petri dish, and freely evaporate the solution under magnetic stirring until the volume is reduced to 14ml. Keep 7ml of the solution, and pour the remaining 7ml of the solution on the polytetrafluoroethylene plate, dry it naturally at room temperature in a ventilated environment until it is completely cured, then continue to dry it for 8 days in the same environment, and get a hybrid material without a support after taking it off. Cut a piece of non-woven fabric with an area of ^160cm2 and spread it on a projection film. The projection film uses a glass plate as a support layer to form a three-layer structure of non-woven fabric-transparency film-glass plate from top to bottom. 7.0ml of the solution was coated on the uppermost layer of non-woven fabric, and the solution was scraped with a glass rod to obtain a uniform sol-gel layer. Also dry at room temperature in a ventilated environment until the film is completely cured, continue to dry for 8 days under the same environment, and peel off the non-woven fabric from the projection film to obtain a hybrid film.

Since the hybrid material and the hybrid film use the same sol-gel solution and similar post-treatment process, the properties of the hybrid material can represent the properties of the hybrid film. The hybrid materials were tested as follows:

(1) Water content: the operations were all carried out at room temperature. A piece of material with a weight ranging from 0.15 to 0.60 g was taken, soaked in distilled water for 2 days, and then the material was taken out of the water. Dry the water on the surface of the material with filter paper, and record the weight value obtained after weighing as m. Then put the material into an oven, bake at 105°C for 6 hours, weigh the dried material, and record the weight as m ₁ . Water content of material = (mm ₁ )×100%/m ₁ .

(2) Ion exchange capacity (IEC) includes Cl ^- type IEC (IEC _Cl ) and OH ^- type IEC (IEC _OH ), and the tests are all carried out at room temperature.

The IEC _Cl test method is as follows: Take a portion of 0.40-0.55 grams of material, soak it in 1mol/L sodium chloride for 2 days, take out the material, soak it in deionized water and change the water four times. Soak the material in 200mL 0.5mol/L sodium sulfate for two days. Keep the sodium sulfate soaking solution, take out the material and re-immerse in 1mol/L sodium chloride for two days, then soak the material in deionized water in the same way as above, finally take out the material, dry at 105°C for 6 hours, weigh the dried Material, the weight is recorded as m ₂ . Using potassium chromate as an indicator, titrate the retained sodium sulfate soaking solution with 0.1mol/L AgNO3. IEC _Cl = moles of silver nitrate consumed/m ₂ .

The IEC _OH test method is as follows: Weigh a portion of 0.40-0.55 grams of material, soak it in 0.5mol/L KOH for 2.5-4 hours, take out the material, soak it in deionized water and change the water four times, and each change of water is separated by 4 hours. Then the material was soaked in 160ml of 0.04mol/L hydrochloric acid for one day. Keep the hydrochloric acid soaking solution, soak the material in deionized water in the same way as above, finally take out the material, bake at 105°C for 6 hours, weigh the dried material, and record the weight as m ₃ . Titrate the retained hydrochloric acid soaking solution with 0.04mol/L KOH. IEC _OH = (0.04 mol/L moles of hydrochloric acid - 0.04 mol/L moles of potassium hydroxide)/m ₃ .

(3) Thermogravimetric analysis test: The material was pre-soaked in methanol for 12 hours, and then placed in vacuum at room temperature for 3 hours after taking it out. The instrument model used was Shimadzu TGA-50H analyzer, and the temperature was raised from room temperature to 800 °C at a rate of 10 °C/min in an air atmosphere.

The mechanical strength, scanning electron microscope (SEM) and OH ^- conductivity tests were carried out on the hybrid membrane, and the test method was referred to "Journal of Membrane Science 307 (2008) 28-36). It’s just that in the SEM test, because the sample is very flexible, it cannot be quenched by liquid nitrogen, but the sample is directly sheared. In addition, the chemical stability test was carried out on the hybrid membrane, and the operation steps were as follows: cut out a membrane with an area of 6cm×6cm, and immerse it in Fenton’s reagent at 80°C (that is, a mixed solution of 4ppm FeCl ₂ and 3% H ₂ O ₂ ) , replace the Fenton reagent every 6h, and take out the membrane every 6h, wipe off the solution on the surface of the membrane and weigh it. The change trend of the wet weight of the membrane with time was investigated.

The test results show that the water content of the membrane prepared in this example is 30.6%; IEC _Cl is 1.73mmol/g, and IEC _OH is 1.26mmol/g, indicating that the prepared membrane is a hybrid anion exchange membrane. Compared with the organic-inorganic hybrid anion exchange membrane in Chinese Patent Application No. 200610097187.7, the IEC _Cl of the membrane prepared in this example is 0.23mmol/g higher than the highest value (1.50mmol/g) reported. The ratio of IEC _OH to IEC _Cl is 72.8%, compared with that reported in "Journal of Applied Polymer Science 107 (2008) 1865-1871), the highest value (52%) reported in this example 20.8% higher, which shows that the film prepared in this example has better alkali resistance.

The results of thermogravimetric analysis showed that the initial degradation temperature of the hybrid membrane prepared in this example was 249.2°C; the thermal degradation temperature was 286.6°C. Compared with that reported in Chinese Patent Application No. 200610097187.7, the initial degradation temperature and thermal degradation temperature are both higher than the reported values, indicating that the hybrid material obtained in this example has higher thermal stability.

The chemical stability test shows that the duration of the film prepared in this example can reach 12h, compared with that reported by "Energy Magazine" (Journal of Power Sources 165 (2007) 16-23), this example is more than the maximum value reported by it (5.2h) is 6.8h higher, indicating that the hybrid film prepared in this example has good oxidation resistance.

The results of mechanical strength analysis showed that the elongation at break of the film prepared in this example was 41%, and the tensile strength was 65.8 MPa. Compared with that reported in European Polymer Journal 42 (2006) 1696-1704, although the elongation at break value is within the reported range (16.7%-42.6%), the tensile strength is not reported six times. It shows that the membrane prepared in this example has better mechanical properties.

SEM observation shows that the surface of the film prepared in this example is uniform and there is no phase separation phenomenon; it can be observed from the cross section that the non-woven fabric fibers are wrapped in the polymer.

The OH ^- conductivity test showed that the conductivity of the film prepared in this example was 4.33×10 ^-4 S/cm.

Since the properties of the hybrid material can represent the properties of the hybrid film, for the convenience of expression, the properties of the material can be attributed to the properties of the film, and the same generalization method will be used in the following examples. Based on the above analysis results, it can be known that this embodiment has obtained a homogeneous organic-inorganic hybrid anion exchange membrane. The membrane has a lower water content and a higher charge capacity, and has good alkali resistance, thermal stability, and Oxidizing and mechanical properties, also has a certain electrical conductivity.

Embodiment 2: the preparation of the copolymer (VBC/KH-570) _-SiO2 hybrid anion exchange membrane of high inorganic phase content

Adopt the same device, preparation process and proportioning relationship as in Example 1, but in the preparation process of the sol-gel solution in step 2, replace 0.38ml EPh with 0.95ml EPh, and replace 0.82ml water with 1.20ml water. The obtained hybrid material was tested for water content, IEC and thermogravimetric analysis; the hybrid film was tested for SEM and mechanical properties.

The test results show that the water content of the film prepared in this example is 16.3%, IEC _Cl is 1.74 mmol/g, and IEC _OH is 1.11 mmol/g.

SEM observation shows that the surface of the film prepared in this example is slightly rough and uneven, and has a small amount of micro-cracks; it shows that too high inorganic phase content will cause phase separation.

The results of thermogravimetric analysis showed that the initial degradation temperature of the hybrid membrane prepared in this example was 237.7°C; the thermal degradation temperature was 257.8°C. This result is lower than the corresponding value obtained in Example 1, which further proves that there is a certain degree of phase separation in the membrane.

The results of mechanical strength analysis showed that the elongation at break of the film prepared in this example was 33%, and the tensile strength was 59.3 MPa.

Based on the above analysis results, it can be seen that the hybrid anion exchange membrane obtained in this example has strong hydrophobicity, and the excessively high inorganic phase in the membrane has caused a slight phase separation problem in the membrane; however, the membrane still has good thermal stability. .

Embodiment 3: the copolymer (VBC/KH-570)-SiO of low inorganic phase content Preparation of _hybrid anion exchange membrane

Adopt the same device, preparation process and proportioning relationship as in Example 1, just in the preparation process of step 2 sol-gel solution, do not add any small molecule silane (that is, do not add 0.38ml EPh) in the polymer solution, 0.82ml of water was replaced with 0.57ml of water. The obtained hybrid material was tested for water content and IEC; the obtained hybrid film was tested for OH ^- conductivity.

The test results showed that the water content of the film prepared in this example was 35.0%, the IEC _Cl was 2.17 mmol/g, and the IEC _OH was 1.47 mmol/g. The OH ^- conductivity of the film was 4.16×10 ^-4 S/cm.

Embodiment 4: the copolymer (VBC/KH-570)-SiO of high charge capacity The preparation of _hybrid anion exchange membrane

Preparation of raw materials: Soak chloroform and petroleum ether in molecular sieves for two days; AIBN recrystallization method and trimethylamine collection steps are the same as in Example 1. Follow these three steps:

1. Preparation of VBC/KH-570 copolymer: use a 250ml round-bottomed three-neck flask equipped with a reflux condenser and nitrogen inlet and outlet, add 9.6ml VBC, 7.1ml KH-570 and 100ml chlorobenzene, and pass argon Under protection, the temperature was raised to 80°C, 0.196g of AIBN was added, and the reaction was stirred for 12 hours under the same environment to obtain a polymer solution. 60ml of chlorobenzene in the polymer solution was removed by rotary evaporation, and the polymer was repeatedly purified five times by petroleum ether precipitation-chloroform dissolution. The purified polymer was dissolved in chloroform to form a 0.22 g/ml solution, and 1 ml of the polymer solution was coated on a tetrafluoroethylene plate, and placed in a vacuum environment at room temperature for 2 days, followed by an NMR test. The results showed that the mole percentage of VBC in the copolymer was 69.0%.

2. Preparation of sol-gel solution: pipette 6.88ml polymer solution into a conical flask, add 25.0ml DMF, mix well, add 0.20ml tetraethoxysilane (TEOS) and 0.19ml EPh, add under stirring 5.48ml of DMF solution of trimethylamine, 0.73ml of ammonia water with a concentration of 0.1mol/L, and then 11ml of ethanol were added, and stirred at room temperature for 16h to obtain a sol-gel solution.

3. Preparation of the hybrid membrane: the sol-gel solution was transferred to a petri dish, and under magnetic stirring, the sol-gel solution was freely volatilized until the volume was reduced to 28ml, and the sol-gel solution was salivated on a polytetrafluoroethylene plate. Ventilate and dry at room temperature and humidity of 45% for 2 days, then raise the temperature from room temperature to 105°C at a rate of 5°C/h, and keep at 105°C for 2.5h. The organic-inorganic hybrid film was obtained after scraping off with a scalpel.

During the water content test process of the hybrid membrane, due to the strong hydrophilicity of the membrane, the method proposed in Example 1 was still used in general, but after the membrane was soaked in a beaker filled with distilled water for two days, the swollen membrane filled the beaker At the bottom, pour out the free water in the upper layer of the beaker, weigh the weight of the wet film by subtraction method, then put the wet film in an oven, bake at 105°C for 10 hours, and calculate the water content of the film to be 2100%. IEC testing indicated that the film had an IEC _Cl of 3.03 mmol/g.

SEM observation shows that the cross-section and surface of the film are even and uniform, indicating that the film obtained in this example is a homogeneous film.

Based on the above analysis results, it can be seen that a hybrid anion exchange membrane with a homogeneous phase and a high charge capacity was obtained in this embodiment, and the high charge capacity brings the film a high swelling performance.

Embodiment 5: the copolymer (3-bromopropene/allyltrimethoxysilane)-SiO of ceramic support body Preparation of _hybrid anion exchange membrane

Preparation of raw materials: (1) Soak chloroform and n-hexane in molecular sieves for one week; (2) AIBN recrystallization method and trimethylamine collection steps are the same as in Example 1. Follow these three steps:

1. Preparation of 3-bromopropene (BPE)/allyltrimethoxysilane (ALLMO) copolymer solution: use a 250ml round-bottomed three-necked flask equipped with a reflux condenser and nitrogen inlet and outlet, add 4.33ml BPE , 8.20ml ALLMO and 100ml chloroform, heated to 60°C under nitrogen protection, added 0.066g AIBN, stirred and reacted for 48h under the same environment to obtain a polymer solution. 50 ml of chloroform in the polymer solution was removed by rotary evaporation. The polymer was purified three times by the method of n-hexane precipitation-chloroform dissolution. The purified polymer was dissolved in 14ml of chloroform and 13ml of N-methylpyrrolidone, and the concentration of the solution was 0.13g/ml.

2. Preparation of sol-gel solution: pipette 11.6ml of polymer solution into a conical flask, add 0.67ml of anilinomethyltriethoxysilane (ND-42), add 1.83ml of triethylamine, 1.92 ml of NaOH solution with a concentration of 0.03mol/L, stirred and reacted at 40°C for 1 hour, then added 4.4ml of ethanol, and continued to stir and reacted at 40°C for 24 hours to obtain a sol-gel solution.

3. Preparation of the hybrid membrane: transfer the sol-gel solution to a petri dish, and freely volatilize under magnetic stirring until the volume is reduced to 12ml. Keep 5ml of sol-gel solution, take 7ml of the solution and drool on the aluminum plate, let it dry naturally for 1 day in a ventilated environment at room temperature, then put it in an oven to raise the temperature from room temperature to 95°C at a rate of 2.5°C/h, and keep it at 95°C After 7 hours, the hybrid material was obtained after scraping off with a scalpel. Take an asymmetric porous α-alumina ceramic sheet with an average surface pore size ranging from 0.4 to 0.5 microns, dip the surface of the ceramic sheet in the retained sol-gel solution for 25 seconds, take it out and let it dry naturally in a ventilated environment at room temperature for 1 day, and then at a rate of 2.5 °C/h from room temperature to 95 °C, and kept at 95 °C for 7 h. The α-alumina ceramic sheet was subjected to the above impregnation-natural drying-heat treatment process again to eliminate possible macropore defects and obtain an organic-inorganic hybrid membrane with a support.

Conduct water content and IEC tests on hybrid materials; conduct SEM and membrane potential tests on hybrid membranes.

The test results show that the water content of the hybrid material prepared in this example is 96.6%, IEC _Cl is 1.67mmol/g, and IEC _OH is 1.03mmol/g, indicating that the prepared membrane is an anion exchange membrane.

Using SEM to observe the surface and cross section of the hybrid film, the results show that the hybrid film prepared in this example has a smooth and uniform surface; the cross section is divided into three layers, the top is a dense layer, and the middle is Al2O3 layer, and the bottom layer corresponds to the porous ceramic support.

The membrane potential test showed that the membrane potential of the hybrid membrane prepared in this example was 4.6mv.

Based on the above analysis results, it can be seen that a hybrid anion exchange membrane supported by porous alumina ceramic sheets was prepared in this example. The membrane has an appropriate water content and charge, and the surface layer of the membrane is homogeneous and dense.

Example 6: Preparation of hybrid anion exchange membrane based on copolymer (BPE/ALLMO)

Chloroform and n-hexane were immersed in molecular sieves for two days, and the recrystallization method of AIBN was the same as in Example 1, followed by the following operations:

1. The preparation of the BPE/ALLMO copolymer solution is exactly the same as Step 1 of Example 5.

2. Preparation of sol-gel solution: pipette 11.6ml of polymer solution into a conical flask, add 0.67ml of aminopropyltriethoxysilane (A-1100), add 3.55ml of tripropylamine, 2.60ml of A sodium acetate solution with a concentration of 0.1 mol/L was stirred and reacted at 10°C for 4 hours, then 5.2ml of ethanol was added, and stirred and reacted at 10°C for 60 hours to obtain a sol-gel solution.

3. Preparation of hybrid film: Stir and volatilize the sol-gel solution at room temperature and a relative humidity of 65% until the volume is reduced to 15ml, coat it on an aluminum plate, and dry it naturally at room temperature in a ventilated environment until the film is completely cured , continued to dry for two weeks under the same environment, and scraped off with a scalpel to obtain a hybrid film.

The test results show that the water content of the hybrid membrane prepared in this example is 62.7%, the IEC _Cl is 1.15 mmol/g, and the IEC _OH is 0.80 mmol/g. It shows that the membrane prepared in this example is a hybrid anion exchange membrane.

Embodiment 7: the preparation of highly stable copolymer (VBC/4-triethoxysilylstyrene) _-SiO2 hybrid anion exchange membrane

The preparation work of raw material: toluene, normal hexane are soaked in molecular sieve two days; The collection process of trimethylamine is the same as embodiment 1, obtains the trimethylamine DMF solution that concentration is 3.27mol/L; Dibenzoyl peroxide (BPO) carries out Purification: Dissolve 10 grams of crude BPO in 40ml of chloroform, filter out the insolubles, pour the filtrate into 100ml of methanol pre-cooled with an ice-salt bath, and then crystals will precipitate out, and the crystallized product will be obtained after filtration. Vacuum dry for one day. Follow these three steps:

1. Preparation of VBC/4-triethoxysilylstyrene copolymer: under the protection of argon, add 0.03mol VBC, 0.07mol 4-triethoxysilylstyrene and 180ml toluene into a 250ml round bottom three-neck flask , heated in an oil bath to 75°C, added 0.145g of BPO, stirred and reacted for 18 hours under the same environment to obtain a polymer solution. Rotary evaporate the polymer solution in the range of 60-75°C until the solution volume is reduced to 2/5 of the original volume. The polymer was purified twice with n-hexane precipitation-toluene dissolution, and the purified polymer was dissolved in 32ml toluene and 60ml DMF to form a solution with a concentration of 0.06g/ml.

2. Preparation of sol-gel solution: pipette 20.0ml of polymer solution into a flat-bottomed flask, add 0.34ml of methyltriethoxysilane, add 1.04ml of DMF solution of trimethylamine and 0.95ml of water under stirring, at 40 Stir the reaction at ℃ for 1 h, then add 3 ml of ethanol, and continue the reaction at 40 °C for 12 h to obtain a sol-gel solution.

3. Preparation of the hybrid membrane: transfer the sol-gel solution to a petri dish, volatilize under magnetic stirring at room temperature and an environment with a relative humidity of 30% until the volume is reduced to 15 ml, and drool on a polytetrafluoroethylene plate. Ventilate and dry at room temperature and a humidity of 45% for 2 days, then put it into an oven, raise the temperature from room temperature to 75°C at a rate of 6°C/h, and keep it at 75°C for 4h. The organic-inorganic hybrid film was obtained after scraping off with a scalpel.

Carry out water content, IEC _Cl and IEC _OH test to the obtained hybrid film; Chemical stability test; Also carry out alkali resistance test, operation is as follows: Take a film with a mass of m ₄ (0.40 g ≤ m ₄ ≤ 0.55 g) , soak in 100ml of sodium hydroxide solution with a concentration of 2mol/L, adjust the temperature of the sodium hydroxide solution to 40°C, take out the membrane after 25h, soak it in deionized water for 16h, and change the water every 4h. Membrane is transferred in the hydrochloric acid of 160ml 0.04mol/L again, back titrates with 0.04mol/L potassium hydroxide after soaking one day, calculates IEC _(OH) =(0.04mol/L hydrochloric acid mol number-0.04mol/L potassium hydroxide moles)/m ₄ .

Tests showed that the water content of the film was 28.4%; IEC _Cl was 1.13 mmol/g and IEC _OH was 0.91 mmol/g.

The chemical stability test shows that the duration of the film is in the range of 20-24 hours, indicating that the hybrid film obtained in this example has high oxidation resistance.

The alkali resistance test shows that the ratio of IEC _(OH) to IEC _OH is 96.7%. Compared with that reported in "Journal of Membrane Science 244 (2004) 25-34", the alkali resistance of the membrane is higher than that reported The optimum value is higher, indicating that the membrane obtained in this example has strong alkali resistance.

Based on the above analysis results, it can be seen that a highly stable hybrid anion exchange membrane was obtained in this example.

Claims (2)

1. A method for preparing an organic-inorganic hybrid anion exchange membrane, first synthesizing a polymer containing halomethyl and alkoxy silicon groups, dissolving it in a mixed solvent to form a concentration of 0.04-0.13 g/ml solution, and then select one or two small molecule alkoxysilanes as a crosslinking agent; it is characterized in that: adding/not adding the crosslinking agent to the solution to obtain a sol-gel precursor; Add tertiary amine, catalyst and water to the sol-gel precursor, react under magnetic stirring for 12-64h (hours), add ethanol to the solution before the reaction or within 4h after the reaction, and obtain the sol-gel solution after the reaction; The sol-gel solution is volatilized until the volume is reduced to 40%-64% of the original, and then coated on the substrate to form a film, and the organic-inorganic hybrid anion exchange membrane is obtained after the film is dried and cured; The mixed solvent is composed of a type A solvent and a type B solvent, wherein the type A solvent is toluene, chloroform or chlorobenzene, and the type B solvent is N,N-dimethylformamide or N-methylpyrrolidone; the type A solvent The volume fraction in the mixed solvent is 17%-52%; The mass ratio of the polymer to the crosslinking agent is 1:0-0.63; The mass ratio of the polymer contained in the sol-gel precursor to tertiary amine, catalyst, and water is 1: 0.16-1.77: 0-0.015: 0.37-1.73, and the volume of the sol-gel precursor to ethanol The ratio is 1:0.14-0.53; The tertiary amine is selected from trimethylamine, triethylamine or tripropylamine; The catalyst is selected from ammonia, sodium formate, sodium acetate, sodium hydroxide, potassium hydroxide; The substrate refers to the inorganic matrix _Al2O3 porous ceramics _{, Al2O3} microfiltration or ultrafiltration membrane, glass plate, aluminum _plate or stainless steel plate, or organic matrix polyester cloth, nylon cloth, glass fiber cloth, nylon cloth, Woven cloth, PTFE board or PVC board; The film-forming method is scraping, spraying, dipping, drooling or coating; The drying and curing of the film is as follows: drying the film at room temperature until the film is completely cured; then continue to dry at room temperature for 8-14 days or raise the temperature from room temperature to 75-105 °C at a rate of 2.5-6 °C/h, keep the temperature 2.5-7h. 2. The method for preparing an organic-inorganic hybrid anion exchange membrane according to claim 1, characterized in that the preparation process of the polymer containing halomethyl and alkoxy silicon groups is as follows: select a A monomer M containing a double bond and an alkoxy silicon group, a monomer N containing a double bond and a halomethyl group, the two monomers are mixed in a molar ratio of M:N=1:0.42-2.34; according to the solvent The volume ratio of the sum of the volume of the two monomers is 3.7-8.3 Add a type A solvent to the mixture of the two monomers; under the protection of an inert gas, the molar ratio of the free radical initiator to the sum of the two monomers is 0.4 %-1.2% Add dibenzoyl peroxide or azobisisobutyronitrile to the two monomer solutions, react at 60-80°C for 12-48h, and remove 0-66% A from the obtained polymer solution by concentrating under reduced pressure After class solvent, the concentrated polymer solution was purified 2-6 times by n-hexane or petroleum ether precipitation-A class solvent dissolution method; The monomer M containing a double bond and an alkoxy silicon group has a chemical formula represented as XR1Si(R) ₃ ; wherein R1 represents an alkyl or aryl group containing 1-7 carbon atoms, and R represents an alkyl or aryl group containing 1 or 2-carbon alkoxy, X represents vinyl or methacrylic; The chemical formula of the monomer N containing a double bond and a halomethyl group is YZR2; wherein Y represents a halomethyl group, Z represents a vinyl or styryl group, and R2 represents an alkyl group containing 0-4 carbons.