阅读说明：本技术 一种离子液体单体聚合制备阴离子交换膜的方法 (Method for preparing anion exchange membrane by polymerizing ionic liquid monomer ) 是由 谢峰 高学强 秦晓平 俞红梅 邵志刚 衣宝廉 于 2018-09-12 设计创作，主要内容包括：一种离子液体单体聚合制备阴离子交换膜的方法,包括如下步骤：低温下一定比例氯甲基苯乙烯、胺单体和引发剂搅拌均匀,得到离子液体与引发剂混合溶液；混合溶液浸润多孔基体薄膜后将薄膜放置在聚酯片中热压聚合制得氯型阴离子交换膜；氯型阴离子交换膜在一定浓度强碱中碱交换,得到氢氧型阴离子交换膜。本发明利用率低温环境降低反应速率,使含聚合引发剂的单体在液态下充分混合,通过热压聚合一步实现离子化和单体聚合反应,没有氯甲基化和胺化步骤、无需使用高致癌的氯甲醚和恶臭的三甲胺,环境友好,步骤简单,可通过单体投放比例直接调节季胺基团浓度和控制交联度,制备出的膜具有较高的离子传导率和良好的机械强度。(A method for preparing an anion exchange membrane by polymerizing an ionic liquid monomer comprises the following steps: uniformly stirring chloromethyl styrene, an amine monomer and an initiator according to a certain proportion at low temperature to obtain a mixed solution of an ionic liquid and the initiator; after the porous matrix film is soaked in the mixed solution, placing the film in a polyester sheet for hot-pressing polymerization to prepare a chlorine type anion exchange membrane; and (3) performing alkali exchange on the chlorine type anion exchange membrane in strong base with a certain concentration to obtain the hydroxide type anion exchange membrane. The method has the advantages that the utilization rate is reduced in a low-temperature environment, the monomers containing the polymerization initiator are fully mixed in a liquid state, ionization and monomer polymerization are realized in one step through hot-pressing polymerization, chloromethylation and amination steps are omitted, highly carcinogenic chloromethyl ether and malodorous trimethylamine are not required, the method is environment-friendly and simple in step, the concentration of quaternary amine groups can be directly adjusted and the crosslinking degree can be controlled through the monomer adding proportion, and the prepared membrane has high ionic conductivity and good mechanical strength.)

1. The method for preparing the anion exchange membrane is characterized by adopting ionic liquid monomer polymerization preparation, and specifically comprises the following steps:

(1) dissolving 1-40 parts by weight of initiator in 5-95 parts by weight of chloromethyl styrene, adding 5-95 parts by weight of amine monomer, and uniformly stirring at-60-10 ℃ to form an ionic liquid monomer mixed solution containing a polymerization initiator;

(2) dropwise adding the monomer mixed solution on the upper surface or the lower surface of the porous film, attaching release polyester sheets on the upper surface and the lower surface of the porous film, uniformly rolling the liquid, and placing the liquid between hot flat plates for hot-pressing polymerization to obtain a polymerization product; the hot-pressing polymerization temperature is 60-140 ℃, the time is 10 min-40 h, the pressure is 0.01-0.5MPa, and the dropping volume of the monomer mixed solution is 0.1-5 times of the volume of the porous film;

(3) taking out the polymerization product, and removing polyester sheets to obtain a chlorine type anion exchange membrane;

(4) and soaking the chlorine type anion exchange membrane in a strong alkali solution for alkali exchange to obtain the hydroxide type anion exchange membrane.

2. The method of preparing an anion exchange membrane of claim 1, wherein: the initiator in the step (1) is at least one of tert-butyl hydroperoxide, benzoyl peroxide, methyl ethyl ketone peroxide, di-tert-amyl peroxide and tert-butyl peroxy-2-ethylhexanoate.

3. The method of preparing an anion exchange membrane of claim 1, wherein: the amine monomer in the step (1) is at least one of triethylamine, tripropylamine, tetramethylethylenediamine, tetramethylhexanediamine, tetramethyldipropylenetriamine, pentamethyldiethylenetriamine or propylenetriamine.

4. The method of preparing an anion exchange membrane of claim 1, wherein: and (2) stirring in the step (1) to be in an ice-water bath environment at 0 ℃.

5. The method of preparing an anion exchange membrane of claim 1, wherein: the porous film in the step (2) is Polyethylene (PE) or polypropylene (PP), the aperture of the porous film is 0.01-1 mu m, the thickness of the porous film is 5-100 mu m, and the porosity of the porous film is 30% -90%.

6. An anion exchange membrane prepared by the method of any of claims 1 to 5.

7. The anion exchange membrane of claim 6 wherein: the ion conductivity of the anion exchange membrane is 10-140 mS/cm, the breaking strength is not lower than 60MPa, the breaking elongation is not lower than 50%, and the anion exchange membrane is adoptedThe power density of the full battery assembled by the film can reach 550mW/cm²The above.

Technical Field

The invention relates to a preparation method of an anion exchange membrane, belonging to the field of fuel cells.

Background

The anion exchange membrane has wide application in water treatment, purification, concentration and separation of substances, chlor-alkali industry, heavy metal recovery, alkaline anion exchange membrane fuel cells, liquid flow energy storage cells, novel supercapacitors and the like, and has important significance for developing anion exchange membranes in modern industry, environment and energy.

The polymer anion exchange membrane for fuel cells should have good chemical stability and mechanical properties in addition to high ionic conductivity. U.S. Pat. No. 4,024,043 discloses a basic anion exchange membrane prepared by immersing a polyethylene film as a substrate in a solution of styrene, divinylbenzene (cross-linking agent) and benzoyl peroxide (initiator), soaking at 70-90 deg.C for 10 minutes to 1 hour, taking out and clamping between two flat glasses, pressurizing, heating and polymerizing to obtain a base membrane, performing chloromethylation reaction in 2.5% of anhydrous stannic chloride chloromethyl ether, and performing quaternization reaction with 25% of trimethylamine acetone solution. The disadvantages of this method are: (1) chloromethyl ether used in the chloromethyl process is a carcinogen; (2) the method uses a trimethylamine solution with malodor to carry out quaternization, which seriously affects the environment; (3) the method comprises the steps of polymerization, chloromethylation and amination, and has more steps, and the reaction degree is not easy to accurately control.

Chinese patent application publication CN200910248539.8 discloses that polytetrafluoroethylene is used as a base film, immersed in a solution composed of chloromethylstyrene, divinylbenzene (cross-linking agent) and benzoyl peroxide (initiator), taken out and clamped between two flat glasses, thermally polymerized at 110-120 ℃ for 3-4 hours, and then quaternized with 33% trimethylamine aqueous solution or a mixed solution of trimethylamine and N, N' -tetramethylethylenediamine to obtain the basic anion exchange membrane. This method has similar disadvantages as described above.

At present, the reports of directly preparing the anion exchange membrane by polymerizing the ionic liquid monomer are less, mainly because the ionic liquid which is in a liquid state at room temperature is less, and the room-temperature ionic liquid which is suitable for polymerizing to form a membrane is less. When the organic substance containing chloromethyl group is mixed with amine substance, the reaction is exothermic, and the generated ionic compound is usually in solid state and can not be directly used as a film.

Disclosure of Invention

The method skillfully utilizes a low-temperature environment to reduce the reaction rate, fully mixes the monomers containing the polymerization initiator in a liquid state, realizes ionization and polymerization reaction in one step through hot pressing, has no chloromethylation and amination steps, does not need to use highly carcinogenic chloromethyl ether and stinky trimethylamine, is environment-friendly and simple in steps, can directly adjust the concentration of quaternary amine groups and control the crosslinking degree through the monomer adding proportion, and has higher ionic conductivity and good mechanical strength.

The invention provides a method for preparing an anion exchange membrane by polymerizing an ionic liquid monomer, which comprises the following steps:

(1) dissolving 1-40 parts by weight of initiator in 5-95 parts by weight of chloromethyl styrene, adding 5-95 parts by weight of amine monomer, and uniformly stirring at-60-10 ℃ to form an ionic liquid monomer mixed solution containing a polymerization initiator;

(2) dropwise adding the monomer mixed solution on the upper surface or the lower surface of the porous film, attaching release polyester sheets on the upper surface and the lower surface of the porous film, rolling the liquid uniformly, and placing the liquid between hot flat plates for hot-pressing polymerization; the polymerization temperature is 60-140 ℃, the polymerization time is 10 min-40 h, the pressure is 0.01-0.5MPa, and the dropping volume of the monomer mixed solution is 0.1-5 times of the volume of the porous film;

(3) taking out the polymerization product, and removing polyester chips to obtain a chlorine type anion exchange membrane;

(4) and soaking the chlorine type anion exchange membrane in a strong alkaline solution for alkali exchange to obtain the hydroxide type anion exchange membrane.

In the step (1), the chloromethyl styrene with the initiator dissolved therein is added to the amine monomer, or the speed of adding the amine monomer to the chloromethyl styrene with the initiator dissolved therein should be slow, and the mixture is stirred while being dripped, and the temperature of the mixed solution is controlled to be low, so that the mixed solution of the monomers is ensured to be liquid rather than solid.

Based on the above technical scheme, preferably, the initiator in the step (1) is at least one of tert-butyl hydroperoxide, benzoyl peroxide, methyl ethyl ketone peroxide, di-tert-amyl peroxide and tert-butyl 2-ethylhexanoate peroxide, and the amine monomer in the step (1) is at least one of triethylamine, tripropylamine, tetramethylethylenediamine, tetramethylhexanediamine, tetramethyldipropylenetriamine, pentamethyldiethylenetriamine or propanetriamine.

Based on the technical scheme, the stirring in the step (1) is preferably in an ice-water bath environment at 0 ℃.

Based on the technical scheme, preferably, the porous film in the step (2) is Polyethylene (PE) or polypropylene (PP), the pore diameter of the porous film is 0.01-1 μm, the thickness of the porous film is 5-100 μm, and the porosity of the porous film is 30% -90%.

The invention also provides an anion exchange membrane prepared by any one of the methods, the ion conductivity of the anion exchange membrane is 10-140 mS/cm, the breaking strength is not lower than 60MPa, the breaking elongation is not lower than 50%, and the power density of a full battery assembled by adopting the anion exchange membrane can reach 550mW/cm²The above.

Advantageous effects

Highly carcinogenic chloromethyl ether and foul trimethylamine are not used, the environment is friendly, the preparation method has simple steps, and chloromethyl styrene and amine monomer are mixed and subjected to ammoniation reaction when in liquid state, so that the product is uniform; the ratio of the quaternary amine functional group and the quaternary amine functional group can be easily adjusted, and the concentration of the quaternary amine functional group in the reaction product can be controlled, so that the contradiction between the ionic conductivity and the mechanical property can be balanced.

Drawings

FIG. 1 is an infrared spectrum of porous polyethylene and the composite anion exchange membrane prepared in example 1.

FIG. 2 is a graph of ion conductivity at different temperatures for the chlorine-type anion-exchange membrane prepared in example 1.

FIG. 3 is a graph of breaking strength versus elongation at break for the composite anion exchange membrane prepared in example 1.

FIG. 4 is a graph of full cell performance of the hydroxide-type composite anion exchange membrane prepared in example 1.

Detailed Description

The following examples further illustrate the preparation of the anion exchange membranes of the present invention.