阅读说明：本技术 一种均相交联结构聚芳醚砜类阴离子交换膜的制备方法 (Preparation method of polyether sulphone anion exchange membrane with homogeneous cross-linked structure ) 是由 廖俊斌 沈江南 高兴 俞欣妍 陈权 于 2019-08-30 设计创作，主要内容包括：本发明公开了一种均相交联结构聚芳醚砜类阴离子交换膜的制备方法,包括：步骤1：1-乙烯基咪唑与二溴烷CH<Sub>2</Sub>Br(CH<Sub>2</Sub>)<Sub>n</Sub>CH<Sub>2</Sub>Br反应得到式(III)所示的1-溴-(n+2)-乙烯基咪唑盐-烷链；步骤2：将式(I)所示的的含氨基聚芳醚砜溶解于溶剂中,然后加入式(II)所示的1-溴-(n+2)-甲基咪唑盐-烷链、式(III)所示的1-溴-(n+2)-乙烯基咪唑盐-烷链、阻聚剂,在20–90℃反应8–24小时,得到咪唑功能化聚芳醚砜；步骤3：将咪唑功能化聚芳醚砜溶于有机溶剂中,加入偶氮二异丁腈得到铸膜液,将铸膜液脱泡后在40–150℃下烘干成膜,得到均相交联结构聚芳醚砜类阴离子交换膜。本发明制备的阴离子交换膜具有膜面电阻低、结构稳定性好、单价阴离子渗透选择性高的特点。<Image he="207" wi="700" file="DDA0002185274200000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>(The invention discloses a preparation method of a polyether sulphone anion exchange membrane with a homogeneous cross-linked structure, which comprises the following steps: step 1: 1-vinylimidazole and dibromoalkane CH 2 Br(CH 2 ) n CH 2 Br reaction to obtain 1-bromo- (n +2) -vinylimidazolium salt-alkyl chain shown in formula (III); step 2: dissolving amino-containing polyarylethersulfone shown in formula (I) in a solvent, adding 1-bromo- (n +2) -methylimidazolium salt-alkyl chain shown in formula (II), 1-bromo- (n +2) -vinylimidazolium salt-alkyl chain shown in formula (III) and a polymerization inhibitor, and reacting at 20-90 ℃ for 8-24 hours to obtain imidazole functionalized polyarylethersulfone; and step 3: dissolving imidazole functionalized polyarylethersulfone in an organic solvent, adding azobisisobutyronitrile to obtain a membrane casting solution, defoaming the membrane casting solution, and drying at 40-150 ℃ to form a membrane, thereby obtaining the polyarylethersulfone anion exchange membrane with the homogeneous cross-linked structure. The anion exchange membrane prepared by the invention has the characteristics of low membrane surface resistance, good structural stability and high monovalent anion permselectivity.)

1. A preparation method of a polyether sulphone anion exchange membrane with a homogeneous cross-linked structure comprises the following steps:

step 1: 1-vinylimidazole and dibromoalkane CH₂Br(CH₂)_nCH₂Br reaction to obtain 1-bromo- (n +2) -vinylimidazolium salt-alkyl chain shown in formula (III); wherein n is 1-16;

step 2: dissolving amino-containing polyarylether sulfone shown in formula (I) in a solvent, adding 1-bromo- (n +2) -methylimidazolium salt-alkyl chain shown in formula (II) and 1-bromo- (n +2) -vinylimidazolium salt-alkyl chain shown in formula (III), adding a polymerization inhibitor, reacting at 20-90 ℃ for 8-24 hours, cooling, precipitating in isopropanol or ethanol, fully washing with water, and drying to obtain imidazole functionalized polyarylether sulfone; the amino-containing polyarylethersulfone is a random copolymer, and the molecular weight is 30000-80000; the molar ratio of the amino-containing polyarylethersulfone to the 1-bromo- (n +2) -methylimidazolium salt-alkane chain to the 1-bromo- (n +2) -vinylimidazolium salt-alkane chain is 1: (0.1-2): (0.1-2), wherein the mass usage of the polymerization inhibitor is 0.5-2.0 wt% of the mass usage of the 1-bromo- (n +2) -vinylimidazolium salt-alkyl chain;

in the formula (I), 60 and 40 represent that two chain links account for 60 percent and 40 percent respectively in molar percentage, and in the formula (II) and the formula (III), m is 1-16; n is 1-16;

and step 3: dissolving the imidazole functionalized polyarylether sulfone obtained in the step 2 in an organic solvent, and adding azobisisobutyronitrile to obtain a membrane casting solution, wherein the mass volume concentrations of the imidazole functionalized polyarylether sulfone and the azobisisobutyronitrile in the membrane casting solution are respectively 3-8% and 0.04-0.15%; and (3) defoaming the casting solution, and drying at 40-150 ℃ to form a membrane to obtain the polyether sulphone anion exchange membrane with the homogeneous cross-linked structure.

2. The method of claim 1, wherein: the thickness of the polyether sulphone anion exchange membrane with the homogeneous cross-linked structure is controlled to be 70-150 mu m.

3. The method of claim 1, wherein: in step 1, 1-vinyl imidazole reacts with dibromoalkane in acetonitrile at 30-60 ℃ for 8-24 hours.

4. The production method according to claim 1 or 3, characterized in that: in the step 1, the molar ratio of the 1-vinyl imidazole to the dibromoalkane is (1-10): 1.

5. The method of claim 1, wherein: in the step 2, the solvent is at least one of DMF, DMAc and NMP.

6. The method of claim 1, wherein: in the step 2, the polymerization inhibitor is BHT.

7. The production method according to claim 1 or 5, characterized in that: in step 2, the molar ratio of the amino-containing polyarylethersulfone, the 1-bromo- (n +2) -methylimidazolium salt-alkane chain to the 1-bromo- (n +2) -vinylimidazolium salt-alkane chain is 3: 3: 0.5.

8. the method of claim 1, wherein: in the step 2, the reaction temperature is 40-90 ℃, and the reaction time is 6-24 hours.

9. The method of claim 8, wherein: in step 2, the reaction temperature is 80 ℃ and the reaction time is 12 hours.

10. The method of claim 1, wherein: in step 3, the organic solvent is selected from one or more of DMF, DMAc and NMP.

(I) technical field

The invention relates to the field of polymer high molecular materials, in particular to a preparation method of a polyarylether sulphone anion exchange membrane with a cross-linked structure, and belongs to the technical field of membranes.

(II) background of the invention

Currently, anion exchange membranes are widely used in diffusion dialysis, electrodialysis, alkaline fuel cells, recovery of useful metals from wastewater, and the like. The separation of ions with the same electric property but different valence states in a mixed salt system is an important practical application of the electrodialysis technology. The choice of monovalent selective ionic membranes is crucial for the particular mixed salt system to be separated. However, at present, most of domestic commercial ionic membrane products are heterogeneous membranes, and are mainly used in separation fields such as primary water treatment and the like with relatively low requirements on ion purity. For monovalent selective anion membranes, researchers at home and abroad have conducted related researches by adopting various strategies according to the separation mechanism of pore size sieving effect (difference in hydrated ion radius), electrostatic repulsion effect (difference in ion charge) or ion hydration energy difference (difference in ion Gibbs hydration energy). At present, commercial monovalent selective anion exchange membranes have the problems of low selectivity and poor long-period stability. For example: in Cl^–/SO₄ ^2–In the separation process, polyethyleneimine is deposited on the surface of the quaternary ammonium polyphenyl ether anionic membrane through electrodeposition, and Cl is caused by the increase of the compactness of the membrane surface layer^–/SO₄ ^2–The relative selectivity of (A) was increased from 0.79 to 4.27(J.Membr.Sci.2017,539, 263-272). A dense charge-carrying layer, such as a "sandwich" structure or the like, is introduced on the membrane surface to function as a pore size sieving or electrostatic exclusion (j.membr. sci.2018,556, 98-106). The electro-deposition method is used for preparing the selective anion membrane with the simulated cell membrane structure, and the surface resistance of the membrane is only 1.92 omega cm²But Cl^–/SO₄ ^2–Has a relative selectivity of 2.20(Sci. Rep.2016,6, 1-1)3) (ii) a The PSS and the HACC electrolyte layer are connected by covalent bonds by utilizing a small-molecule photocrosslinking agent to ensure the stability of a modified layer and optimize a selective anionic membrane

Is 4.36 (4.46. omega. cm)²) (J.Membr.Sci.2017,543, 310-318). However, the major problems with the above surface modification strategies are: (i) the polyelectrolyte surface modification common anionic membrane is similar to a bipolar membrane in structure, the modification cortex is mainly combined with the basement membrane under the action of van der Waals force, and when the applied voltage is higher than the water dissociation voltage of the membrane, the falling of the modification layer causes the remarkable attenuation of performance in the application process, so that the service life is shortened; (ii) to ensure a low sheet resistance, the thin modification layer has limited anion sieving ability or electrostatic exclusion and exhibits low permselectivity (permselectivity)<6) (ii) a (iii) The increase in surface density, the introduction of an oppositely charged layer or the increase in film thickness increases the sheet resistance of the film.

Disclosure of the invention

The invention aims to provide a preparation method of a homogeneous cross-linked polyarylether sulphone anion exchange membrane with a good structural stability and high monovalent anion permeability selectivity.

In order to achieve the above purpose, the invention adopts the following technical scheme:

a preparation method of a polyether sulphone anion exchange membrane with a homogeneous cross-linked structure comprises the following steps:

step 1: 1-vinylimidazole and dibromoalkane CH₂Br(CH₂)_nCH₂Br reaction to obtain 1-bromo- (n +2) -vinylimidazolium salt-alkyl chain shown in formula (III); wherein n is 1-16;

step 2: dissolving amino-containing polyarylether sulfone shown in formula (I) in a solvent, adding 1-bromo- (n +2) -methylimidazolium salt-alkyl chain shown in formula (II) and 1-bromo- (n +2) -vinylimidazolium salt-alkyl chain shown in formula (III), adding a polymerization inhibitor, reacting at 20-90 ℃ for 8-24 hours, cooling, precipitating in isopropanol or ethanol, fully washing with water, and drying to obtain imidazole functionalized polyarylether sulfone; the amino-containing polyarylethersulfone is a random copolymer, and the molecular weight is 30000-80000; the molar ratio of the amino-containing polyarylethersulfone to the 1-bromo- (n +2) -methylimidazolium salt-alkane chain to the 1-bromo- (n +2) -vinylimidazolium salt-alkane chain is 1: (0.1-2): (0.1-2), wherein the mass usage of the polymerization inhibitor is 0.5-2.0 wt% of the mass usage of the 1-bromo- (n +2) -vinylimidazolium salt-alkyl chain;

in the formula (I), 60 and 40 represent that two chain links account for 60 percent and 40 percent respectively in molar percentage, and in the formula (II) and the formula (III), m is 1-16; n is 1-16;

and step 3: dissolving the imidazole functionalized polyarylether sulfone obtained in the step 2 in an organic solvent, and adding Azobisisobutyronitrile (AIBN) to obtain a membrane casting solution, wherein the mass volume concentrations of the imidazole functionalized polyarylether sulfone and the azobisisobutyronitrile in the membrane casting solution are respectively 3-8% and 0.04-0.15%; and (3) defoaming the casting solution, and drying at 40-150 ℃ to form a membrane to obtain the polyarylether sulfone anion exchange membrane (c-PAES-IM) with the homogeneous cross-linked structure.

The polyether sulphone anion exchange membrane with the homogeneous cross-linking structure prepared by the invention is made of polyether sulphone with the cross-linking structure, and due to uncertain cross-linking sites, a plurality of possible cross-linking structures exist, wherein one possible cross-linking structure is as follows:

according to the invention, by introducing end-position hydrophilic conductive imidazole salt and regulating and controlling the length of a hydrophobic alkyl chain segment in a side chain, an anion transmission channel is constructed, and the low sheet resistance of the membrane is ensured; meanwhile, a proper amount of flexible side alkyl chain terminal vinyl is polymerized to form a homogeneous polymer anionic membrane with different density cross-linking structures, so that the stability of a chemical structure is ensured.

Preferably, the thickness of the anion exchange membrane of the polyarylether sulphone type with the homogeneous cross-linked structure is controlled to be 70-150 mu m.

Preferably, in step 1, the reaction of 1-vinylimidazole with dibromoalkane is carried out in acetonitrile at 30-60 ℃ for 8-24 hours.

Preferably, in the step 1, the molar ratio of the 1-vinylimidazole to the dibromoalkane is (1-10): 1.

Preferably, in step 2, the polymerization inhibitor is BHT.

Preferably, in step 2, the solvent is at least one of DMF, DMAc, and NMP.

Preferably, in step 2, the molar ratio of the amino-containing polyarylethersulfone, 1-bromo- (n +2) -methylimidazolium salt-alkane chain to 1-bromo- (n +2) -vinylimidazolium salt-alkane chain is 3: 3: 0.5.

preferably, in the step 2, the reaction temperature is 40-90 ℃, and the reaction time is 6-24 hours; further preferably 80 ℃ for 12 hours.

Preferably, in step 3, the organic solvent is one or more selected from DMF, DMAc, NMP.

In the present invention, the amino group-containing polyarylethersulfone represented by the formula (I) can be prepared by a method disclosed in the literature, such as Journal of Membrane Science 577(2019) 153-; journal of Membrane Science 574(2019) 181-195.

The invention specifically recommends that the amino-containing polyarylethersulfone is prepared by the following method: adding monomers of 4,4 ' -difluorodiphenyl sulfone, 2 ' -bis (4-hydroxyphenyl) hexafluoropropane and 2,2 ' -bis (3-amino-4-hydroxyphenyl) hexafluoropropane into a high boiling point aprotic solvent, wherein the feeding molar ratio of the 2,2 ' -bis (4-hydroxyphenyl) hexafluoropropane to the 2,2 ' -bis (3-amino-4-hydroxyphenyl) hexafluoropropane is 40%: 60 percent, copolycondensating for 4 to 12 hours under the nitrogen atmosphere and the temperature of 100 ℃ and 180 ℃, and carrying out post-treatment on the reaction mixture to obtain the amino-containing polyarylether sulfone.

In the present invention, it is preferable that the ratio of the amount of the substance of 4,4 ' -difluorodiphenyl sulfone to the total amount of the substances of 2,2 ' -bis (4-hydroxyphenyl) hexafluoropropane and 2,2 ' -bis (3-amino-4-hydroxyphenyl) hexafluoropropane monomers is 1: 1.

Preferably, potassium carbonate is added to the polymerization system as a catalyst and toluene is added as a water-carrying agent. It is further preferred that potassium carbonate be used in an amount of 2 to 5 times, preferably 2 times, the molar amount of the monomer 4, 4' -difluorodiphenyl sulfone. The volume ratio of the toluene to the high-boiling-point aprotic solvent is 0.2-0.7: 1.

preferably, the high boiling point solvent used is one or more of Dimethylformamide (DMF), dimethylacetamide (DMAc), N-methylpyrrolidone (NMP).

The copolycondensation reaction in the steps is carried out for 4-12 hours at the temperature of 100-180 ℃, and nitrogen is introduced for protection in the whole process to avoid oxidation. Preferably, the copolycondensation reaction conditions are as follows: in N₂The reaction was carried out at 155 ℃ for 4 hours under an atmosphere and at 165 ℃ for 3 hours. The reaction at low temperature of 150 ℃ can avoid gelation, and the subsequent reaction at elevated temperature is beneficial to improving the molecular weight of the polymer.

Preferably, the post-treatment method comprises the following steps: when the polymer solution is cooled to room temperature, the polymer solution is poured into isopropanol or methanol solution, and is flocculated under high-speed stirring to obtain precipitate. And (3) carrying out suction filtration separation to obtain a brown solid, repeatedly washing with isopropanol or methanol and water for many times, and carrying out vacuum drying at 40-80 ℃ for 12-24 hours.

In the present invention, the 1-bromo- (n +2) -methylimidazolium salt-alkane chain represented by the formula (II) can be prepared according to a method disclosed in the literature.

Compared with the prior art, the invention has the advantages that:

(1) the ion exchange membrane prepared by the invention contains crosslinking groups, and a crosslinking network structure can be formed in the membrane material through crosslinking, so that the chemical stability and the osmotic selectivity of the ion exchange membrane are further improved.

(2) By regulating and controlling the length of the hydrophobic chain segment, the hydrophilic chain segment and the alkyl in the cross-linked side chain, a high-efficiency ion transfer rate and an excellent selective ion transmission channel are formed, so that the membrane has good monovalent anion selectivity.

(3) The proper amount of flexible side alkyl chain terminal imidazole, a cross-linked homogeneous membrane structure formed by chemical bonds between a conductive side chain and a rigid main chain ensure low surface resistance and structural stability of the membrane.

(IV) description of the drawings

FIG. 1 example 1 is a preparation of 1-bromo- (n +2) -vinylimidazolium salt-alkane chains¹H NMR spectrum;

FIG. 2 is an FTIR spectrum of the cross-linked polyarylether sulfone anion exchange membrane prepared in example 1;

FIG. 3 is a Thermogravimetry (TGA) of the cross-linked polyarylethersulfone anion-exchange membrane of example 1.

Detailed Description

The technical solution of the present invention is further described below with reference to specific examples.