Preparation method of an ion exchange membrane with a through-plane orientation structure

Abstract

The present invention discloses a preparation method of an ion exchange membrane with a through-surface orientation structure, which includes performing ion exchange on several polymers and fillers all or partially containing a magnetic-responsive structure before preparing a film with an aqueous solution of an ion replacement agent, washing away the excess ions and then dissolving them in a single solvent to form a film-forming solution, or not performing ion exchange before film preparation and dissolving them in a mixed solvent with a boiling point difference of no more than 4 °C under normal pressure conditions to form a film-forming solution, or a treatment technique combining the two; pouring the film-forming solution into a petri dish, and evaporating the solvent to form a film under a certain vertical magnetic field intensity and a certain temperature; performing alkalization or acidification treatment to obtain an ion exchange membrane with a through-surface orientation structure. Under the conditions of the same film-forming raw materials and the same magnetic field intensity, the present invention can enhance the magnetic response ability of the film-forming solution, improve the aggregation size and orientation regularity of the hydrophilic phase during the entire film-forming process, and obtain a significant benefit in ion transport performance in the direction of the film through-surface.

Description

Technical Field

[0001] The present invention relates to the technical field of new materials, and particularly to a preparation method of an ion exchange membrane with a through-plane orientation structure. Background Art

[0002] Ion exchange membranes are key materials in clean energy or new energy storage fields such as fuel cells, water electrolyzers, ion batteries, and flow batteries. In actual electrochemical energy conversion devices in these application fields, the ion exchange membrane is located between two electrodes, and ions need to cross the membrane in the through-plane direction (i.e., the through-thickness direction) of the ion exchange membrane for transmembrane transport to achieve energy conversion. However, ion exchange membranes prepared by general film-making methods usually have an isotropic ion transport structure, which is not conducive to the rapid transmembrane transport of ions between the two electrodes along the shortest path in the through-plane direction of the membrane.

[0003] To improve the energy conversion efficiency, an ideal ion exchange membrane should have a through-plane orientation transport structure. Although there are some reports on constructing a through-plane orientation transport structure in ion exchange membranes using electric and magnetic fields, the degree of orientation is low, and the advantage of ion conductivity concentrated in the through-plane direction is not obvious.

[0004] In related technologies, such as the Chinese patent with the publication number CN109078501A, a preparation method of an ion exchange membrane with an ordered ion conduction structure is disclosed. This patent can orderly regulate the ion conduction structure of the ion exchange membrane and prepare an efficient and durable ion exchange membrane with an ordered ion conduction structure.

[0005] However, existing reports are limited to synthesizing polymers or fillers with electric or magnetic field responsiveness and preparing films under electric or magnetic field conditions, lacking a comprehensive consideration and optimization of the entire film-making system and process, such as the influence of ions and solvents in the film-making solution.

[0006] Therefore, there is an urgent need to develop a more overall perspective film-making method in this research field to improve the degree of orientation of ion exchange membranes, so as to obtain more significant benefits in ion transport performance in the through-plane direction, thereby further improving the efficiency of related electrochemical energy conversion devices. Summary of the Invention

[0007] To solve the above problems, the present invention provides a preparation method of an ion exchange membrane with a through-plane orientation structure to solve this problem.

[0008] To achieve the above object, the present application provides the following technical solutions:

[0009] A preparation method of an ion exchange membrane with a through-plane orientation structure, comprising the following steps:

[0010] S001: Either use polymer A with a magnetic-responsive structure alone or use one of the following compositions. Before film formation, perform ion exchange in an aqueous solution of an ion exchanger, wash away the excess ions, and then dissolve it in a single solvent to prepare a film-forming solution.

[0011] The said composition includes: Composition ① and / or Composition ②:

[0012] Composition ① is any combination of two of polymer B, polymer A with a magnetic-responsive structure, and filler a with a magnetic-responsive structure;

[0013] Composition ② is a combination of polymer B, polymer A with a magnetic-responsive structure, and filler a with a magnetic-responsive structure;

[0014] S002: Pour the film-forming solution into a petri dish and form a film by evaporating the solvent for 12 - 48 hours under the conditions of a vertical magnetic field strength of 0.001 - 5 Tesla and a temperature of 40 - 120 °C.

[0015] S003: Alkalize or acidify the formed film to obtain an ion exchange membrane with a through-surface orientation structure.

[0016] It is further set as follows: In step S001, the film-forming solution can also be prepared through the following steps:

[0017] Either use polymer A with a magnetic-responsive structure alone or use one of the following compositions. Dissolve it in a mixed solvent with a boiling point difference of no more than 4 °C under normal pressure to prepare a film-forming solution.

[0018] The said composition includes: Composition ① and / or Composition ②:

[0019] Composition ① is any combination of two of polymer B, polymer A with a magnetic-responsive structure, and filler a with a magnetic-responsive structure;

[0020] Composition ② is a combination of polymer B, polymer A with a magnetic-responsive structure, and filler a with a magnetic-responsive structure.

[0021] It is further set as follows: In step S001, the film-forming solution can also be prepared through the following steps:

[0022] Either use polymer A with a magnetic-responsive structure alone or use one of the following compositions. Before film formation, perform ion exchange in an aqueous solution of an ion exchanger, wash away the excess ions, and then dissolve it in a mixed solvent with a boiling point difference of no more than 4 °C under normal pressure to prepare a film-forming solution.

[0023] The said composition includes: Composition ① and / or Composition ②:

[0024] The composition ① is a combination of any two of polymer B, polymer A with a magnetic-responsive structure, and filler a with a magnetic-responsive structure;

[0025] The composition ② is a combination of polymer B, polymer A with a magnetic-responsive structure, and filler a with a magnetic-responsive structure.

[0026] It is further set that: the polymer main chain in the polymer A is one of polyimide, polyamide, polyether ether ketone, polysulfone, polyether sulfone, polytetrafluoroethylene, polydimethylsiloxane, polystyrene, polybenzimidazole, polyphenylene ether, polyethylene, polyvinyl chloride, polyvinyl pyridine, or polyvinyl cyclohexane.

[0027] It is further set that: the magnetic-responsive structure of the polymer A is one of ferrocenium cation group, cobaltocenium cation group, nickelocenium cation group, or ferrocyanide coordination group.

[0028] It is further set that: the filler a is one of modified iron oxide particles, modified erbium oxide particles, modified carbon nanotubes, modified halloysite, modified rectorite, modified montmorillonite, modified silica, modified titanium dioxide, modified graphene, modified graphene oxide, modified boron nitride, or modified carbon nitride.

[0029] It is further set that: the magnetic-responsive structure of the filler a is iron oxide, erbium oxide, or Prussian blue analog.

[0030] It is further set that: the polymer B is one of polyimide, polysulfone, polyether sulfone, polystyrene, polyphenylene sulfide, polyvinyl pyridine, polypropylene, polyacrylonitrile, polyphosphazene, polyvinylidene fluoride, or polymethyl methacrylate.

[0031] It is further set that: when the polymer A and the polymer B are used to prepare a film-forming solution, the mass ratio is (1 - 99):(1 - 99); when the polymer A and the filler a are used to prepare a film-forming solution, the mass ratio is (50 - 99):(1 - 50); when the polymer B and the filler a are used to prepare a film-forming solution, the mass ratio is (50 - 99):(1 - 50); when the polymer A, the polymer B, and the filler a are used to prepare a film-forming solution, the mass ratio is (1 - 98):(1 - 98):(1 - 50).

[0032] It is further set that: the ion-exchange agent is one of sodium molybdate, sodium tungstate, potassium tetrafluoroborate, potassium hexafluorophosphate, potassium hexafluoroantimonate, lithium bis(trifluoromethanesulfonyl)imide, gadolinium nitrate, terbium chloride, dysprosium chloride, holmium nitrate, erbium nitrate, or thulium bromide.

[0033] It is further set that: the single solvent is one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, or m-cresol.

[0034] Further set as: the mixed solvent with a boiling point difference of no more than 4 °C under atmospheric pressure is one of N,N-dimethylformamide and 1-methylcyclohexanol, N,N-dimethylacetamide and 2-methylcyclohexanol, dimethyl sulfoxide and 3-nonanol, dimethyl sulfoxide and 1,2-butanediol, dimethyl sulfoxide and 2-ethylbutyric acid, N-methylpyrrolidone and 5-methyl-5-nonanol, N-methylpyrrolidone and α-phenylethyl alcohol, m-cresol and 5-methyl-5-nonanol, m-cresol and α-phenylethyl alcohol.

[0035] Further set as: the volume ratio of the two solvent components in the mixed solvent with a boiling point difference of no more than 4 °C under atmospheric pressure is (10-90):(10-90).

[0036] Further set as: the modification is surface quaternization, or a three-step combination of electrodeposition of a Prussian blue analogue coating on the surface - deposition of a catechol coating - sulfonation.

[0037] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0038] The present invention adopts the treatment technology of ion replacement before film formation, preparing a film-forming solution with a mixed solvent having a boiling point difference of no more than 4 °C under atmospheric pressure, or a combination of the two. Under the condition of the same film-forming raw materials and the same magnetic field strength, it can enhance the magnetic response ability of the film-forming solution, and improve the aggregation size and orientation regularity of the hydrophilic phase during the entire film-forming process. This method breaks through the limitation of only synthesizing polymers or fillers with electric or magnetic field responsiveness and forming films under electric or magnetic field conditions, comprehensively considers and optimizes important factors such as ions and solvents in the entire film-forming system and process, greatly improves the orientation degree of the ion exchange membrane, and obtains a more significant ion transport performance benefit in the direction of the permeation surface. Specific Embodiments

[0039] The technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will describe the technical solutions of this application clearly and completely in combination with the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without creative efforts belong to the scope of protection of this application. It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined arbitrarily with each other.

[0041] In some exemplary embodiments, a method for preparing an ion exchange membrane with a through-surface orientation structure disclosed by the present invention includes:

[0042] Separately polymer A;

[0043] And / or any two combinations of polymer B, polymer A with a magnetic-responsive structure, and filler a with a magnetic-responsive structure;

[0044] And / or a combination of polymer B, polymer A with a magnetic-responsive structure, and filler a with a magnetic-responsive structure. Before film formation, perform ion exchange in an aqueous solution of an ion-exchanging agent, wash away the excess ions, and then dissolve in a single solvent to form a film-forming solution;

[0045] Furthermore, the film-forming solution can also be prepared through the following steps:

[0046] Separately polymer A;

[0047] And / or any two combinations of polymer B, polymer A with a magnetic-responsive structure, and filler a with a magnetic-responsive structure;

[0048] And / or a combination of polymer B, polymer A with a magnetic-responsive structure, and filler a with a magnetic-responsive structure. Dissolve in a mixed solvent with a boiling point difference of no more than 4 degrees Celsius under normal pressure to form a film-forming solution;

[0049] Even further, the film-forming solution can also be prepared through the following steps:

[0050] Separately polymer A;

[0051] And / or any two combinations of polymer B, polymer A with a magnetic-responsive structure, and filler a with a magnetic-responsive structure;

[0052] And / or a combination of polymer B, polymer A with a magnetic-responsive structure, and filler a with a magnetic-responsive structure. Before film formation, perform ion exchange in an aqueous solution of an ion-exchanging agent, wash away the excess ions, and then dissolve in a mixed solvent with a boiling point difference of no more than 4 degrees Celsius under normal pressure to form a film-forming solution;

[0053] Pour the film-forming solution into a petri dish, and under the conditions of a magnetic field strength of 0.001 - 5 Tesla and a temperature of 40 - 120 °C in the vertical direction, evaporate the solvent for 12 - 48 hours to form a film;

[0054] Alkalize or acidify the formed film to obtain an ion exchange membrane with a through-plane orientation structure.

[0055] The polymer main chain in polymer A is one of polyimide, polyamide, polyether ether ketone, polysulfone, polyether sulfone, polytetrafluoroethylene, polydimethylsiloxane, polystyrene, polybenzimidazole, polyphenylene ether, polyethylene, polyvinyl chloride, polyvinyl pyridine, or polyvinyl cyclohexane; the magnetic-responsive structure of polymer A is one of ferrocene cationic group, cobaltocene cationic group, nickelocene cationic group, or ferrocyanide coordination group.

[0056] Filler a is one of modified iron oxide particles, modified erbium oxide particles, modified carbon nanotubes, modified halloysite, modified rectorite, modified montmorillonite, modified silica, modified titanium dioxide, modified graphene, modified graphene oxide, modified boron nitride, or modified carbon nitride; the magnetic-responsive structure of filler a is iron oxide, erbium oxide, or Prussian blue analog.

[0057] Polymer B is one of polyimide, polysulfone, polyether sulfone, polystyrene, polyphenylene sulfide, polyvinyl pyridine, polypropylene, polyacrylonitrile, polyphosphazene, polyvinylidene fluoride, or polymethyl methacrylate.

[0058] When polymer A and polymer B are used to prepare the film-forming solution, the mass ratio is (1 - 99):(1 - 99); when polymer A and filler a are used to prepare the film-forming solution, the mass ratio is (50 - 99):(1 - 50); when polymer B and filler a are used to prepare the film-forming solution, the mass ratio is (50 - 99):(1 - 50); when polymer A, polymer B, and filler a are used to prepare the film-forming solution, the mass ratio is (1 - 98):(1 - 98):(1 - 50).

[0059] The ion exchanger is one of sodium molybdate, sodium tungstate, potassium tetrafluoroborate, potassium hexafluorophosphate, potassium hexafluoroantimonate, lithium bis(trifluoromethanesulfonyl)imide, gadolinium nitrate, terbium chloride, dysprosium chloride, holmium nitrate, erbium nitrate, or thulium bromide.

[0060] The single solvent is one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, or m-cresol.

[0061] The mixed solvent with a boiling point difference of no more than 4 °C under atmospheric pressure is one of the groups of N,N-dimethylformamide and 1-methylcyclohexanol, N,N-dimethylacetamide and 2-methylcyclohexanol, dimethyl sulfoxide and 3-nonanol, dimethyl sulfoxide and 1,2-butanediol, dimethyl sulfoxide and 2-ethylbutyric acid, N-methylpyrrolidone and 5-methyl-5-nonanol, N-methylpyrrolidone and α-phenylethyl alcohol, m-cresol and 5-methyl-5-nonanol, m-cresol and α-phenylethyl alcohol, and the volume ratio of the two solvent components in the mixed solvent is (10 - 90):(10 - 90).

[0062] The modification is carried out by surface quaternization or a three-step combination of electrodeposition of a surface Prussian blue analogue coating, deposition of a catechol coating, and sulfonation.

[0063] The detailed embodiments of the preparation method of the ion exchange membrane with a through-plane orientation structure are as follows:

[0064] Example 1:

[0065] Polyimide with a ferrocene cationic group structure and polystyrene with a mass ratio of 99:1 are subjected to ion exchange in an aqueous solution of sodium molybdate. After washing away the excess ions, they are dissolved in a mixed solvent to prepare a membrane-forming solution. After the membrane-forming solution is fully dissolved, it is left standing for defoaming; the membrane-forming solution is poured into a petri dish, and under the condition of a vertical magnetic field strength of 5 Tesla and a temperature of 120 °C, the solvent is evaporated for 12 hours to form a membrane; the membrane is alkalized to obtain an ion exchange membrane with a through-plane orientation structure.

[0066] Furthermore, the mixed solvent in Example 1 is: m-cresol and 5-methyl-5-nonanol with a volume ratio of 75:25, and the boiling point difference is no more than 4 °C under atmospheric pressure.

[0067] Example 2:

[0068] Polyamide with a cobaltocene cationic group structure, polyphenylene sulfide, and surface quaternized modified erbium oxide particles with a mass ratio of 98:1:1 are subjected to ion exchange in an aqueous solution of sodium tungstate. After washing away the excess ions, they are dissolved in N,N-dimethylacetamide to prepare a membrane-forming solution. After full dissolution, it is left standing for defoaming; the membrane-forming solution is poured into a petri dish, and under the condition of a vertical magnetic field strength of 4 Tesla and a temperature of 80 °C, the solvent is evaporated for 30 hours to form a membrane; the membrane is alkalized to obtain an ion exchange membrane with a through-plane orientation structure.

[0069] Example 3:

[0070] Perform ion exchange in an aqueous solution of potassium tetrafluoroborate on polyether ether ketone with a nickelocene cation group structure, polyvinylpyridine, and surface quaternized modified erbium oxide particles with a mass ratio of 1:98:1. After washing away the excess ions, dissolve them in N-methylpyrrolidone to prepare a membrane-forming solution. After complete dissolution, let it stand for defoaming; pour the membrane-forming solution into a petri dish, and under the condition of a magnetic field strength of 5 Tesla in the vertical direction and a temperature of 40 °C, evaporate the solvent for 48 hours to form a membrane; perform alkalization treatment on the membrane to obtain an ion exchange membrane with a through-surface orientation structure.

[0071] Example 4:

[0072] Perform ion exchange in an aqueous solution of potassium hexafluorophosphate on polysulfone with a ferrocene cation group structure, polyimide, and surface quaternized modified iron oxide particles with a mass ratio of 40:40:20. After washing away the excess ions, dissolve them in a mixed solvent to prepare a membrane-forming solution. After complete dissolution, let it stand for defoaming; pour the membrane-forming solution into a petri dish, and under the condition of a magnetic field strength of 3 Tesla in the vertical direction and a temperature of 90 °C, evaporate the solvent for 24 hours to form a membrane; perform alkalization treatment on the membrane to obtain an ion exchange membrane with a through-surface orientation structure;

[0073] Furthermore, the mixed solvent in Example 4 is: m-cresol and α-phenylethyl alcohol with a volume ratio of 75:25, and the boiling point difference under atmospheric pressure is not more than 4 degrees Celsius.

[0074] Example 5:

[0075] Perform ion exchange in an aqueous solution of potassium hexafluoroantimonate on polyethersulfone with a ferrocene cation group structure and polysulfone with a mass ratio of 1:99. After washing away the excess ions, dissolve them in m-cresol to prepare a membrane-forming solution. After complete dissolution, let it stand for defoaming; pour the membrane-forming solution into a petri dish, and under the condition of a magnetic field strength of 5 Tesla in the vertical direction and a temperature of 100 °C, evaporate the solvent for 24 hours to form a membrane; perform alkalization treatment on the membrane to obtain an ion exchange membrane with a through-surface orientation structure.

[0076] Example 6:

[0077] Perform ion exchange in an aqueous solution of lithium bis(trifluoromethanesulfonyl)imide on polytetrafluoroethylene with a ferrocene cation group structure, surface quaternized modified iron oxide particles with a mass ratio of 50:50. After washing away the excess ions, dissolve them in N,N-dimethylformamide to prepare a membrane-forming solution. After complete dissolution, let it stand for defoaming; pour the membrane-forming solution into a petri dish, and under the condition of a magnetic field strength of 0.5 Tesla in the vertical direction and a temperature of 70 °C, evaporate the solvent for 36 hours to form a membrane; perform alkalization treatment on the membrane to obtain an ion exchange membrane with a through-surface orientation structure.

[0078] Example 7:

[0079] Dissolve polyetheretherketone with ferrocene cationic group structure and surface quaternary ammonium modified erbium oxide particles with a mass ratio of 99:1 in a mixed solvent to prepare a membrane-forming solution. After complete dissolution, let it stand for defoaming; pour the membrane-forming solution into a petri dish, and under the condition of a magnetic field strength of 3 Tesla in the vertical direction, evaporate the solvent at 110 °C for 18 hours to form a membrane; perform alkalization treatment on the membrane to obtain an ion exchange membrane with a through-surface orientation structure;

[0080] Furthermore, the mixed solvent in Example 7 is: N,N-dimethylformamide and 1-methylcyclohexanol with a volume ratio of 90:10, and the boiling point difference under atmospheric pressure is no more than 4 °C.

[0081] Example 8:

[0082] Dissolve polysulfone with ferrocene cationic group structure in a mixed solvent to prepare a membrane-forming solution. After complete dissolution, let it stand for defoaming; pour the membrane-forming solution into a petri dish, and under the condition of a magnetic field strength of 1.5 Tesla in the vertical direction, evaporate the solvent at 85 °C for 24 hours to form a membrane; perform alkalization treatment on the membrane to obtain an ion exchange membrane with a through-surface orientation structure;

[0083] Furthermore, the mixed solvent in Example 8 is: N,N-dimethylformamide and 1-methylcyclohexanol with a volume ratio of 60:40, and the boiling point difference under atmospheric pressure is no more than 4 °C.

[0084] Example 9:

[0085] Perform ion exchange of polyethersulfone with a mass ratio of 99:1 and surface quaternary ammonium modified iron oxide particles in an aqueous solution of sodium tungstate. After washing away the excess ions, dissolve them in a mixed solvent to prepare a membrane-forming solution. After complete dissolution, let it stand for defoaming; pour the membrane-forming solution into a petri dish, and under the condition of a magnetic field strength of 0.001 Tesla in the vertical direction, evaporate the solvent at 60 °C for 36 hours to form a membrane; perform alkalization treatment on the membrane to obtain an ion exchange membrane with a through-surface orientation structure;

[0086] Furthermore, the mixed solvent in Example 9 is: N,N-dimethylacetamide and 2-methylcyclohexanol with a volume ratio of 40:60, and the boiling point difference under atmospheric pressure is no more than 4 °C.

[0087] Example 10:

[0088] Polystyrene with ferrocyanide coordination group structure, polypropylene with a mass ratio of 25:25:50, and silica modified by the three-step combination of electrodeposition of surface Prussian blue analogue coating - catechol coating deposition - sulfonation were subjected to ion exchange in an aqueous gadolinium nitrate solution. After washing away the excess ions, they were dissolved in N,N-dimethylformamide to prepare a film-forming solution. After complete dissolution, it was left standing to remove bubbles; the film-forming solution was poured into a petri dish, and under the condition of a magnetic field strength of 0.1 Tesla in the vertical direction and a temperature of 80 °C, the solvent was evaporated for 30 hours to form a film; the film was acidified to obtain an ion exchange membrane with a through-plane orientation structure.

[0089] Example 11:

[0090] Polybenzimidazole with ferrocyanide coordination group structure, polyacrylonitrile with a mass ratio of 70:15:15, and titanium dioxide modified by the three-step combination of electrodeposition of surface Prussian blue analogue coating - catechol coating deposition - sulfonation were subjected to ion exchange in an aqueous terbium chloride solution. After washing away the excess ions, they were dissolved in N,N-dimethylacetamide to prepare a film-forming solution. After complete dissolution, it was left standing to remove bubbles; the film-forming solution was poured into a petri dish, and under the condition of a magnetic field strength of 4 Tesla in the vertical direction and a temperature of 110 °C, the solvent was evaporated for 25 hours to form a film; the film was acidified to obtain an ion exchange membrane with a through-plane orientation structure.

[0091] Example 12:

[0092] Polyphenylene ether with ferrocyanide coordination group structure, polyphosphazene with a mass ratio of 40:50:10, and carbon nanotubes modified by the three-step combination of electrodeposition of surface Prussian blue analogue coating - catechol coating deposition - sulfonation were subjected to ion exchange in an aqueous dysprosium chloride solution. After washing away the excess ions, they were dissolved in N-methylpyrrolidone to prepare a film-forming solution. After complete dissolution, it was left standing to remove bubbles; the film-forming solution was poured into a petri dish, and under the condition of a magnetic field strength of 3 Tesla in the vertical direction and a temperature of 100 °C, the solvent was evaporated for 30 hours to form a film; the film was acidified to obtain an ion exchange membrane with a through-plane orientation structure.

[0093] Example 13:

[0094] Polyvinylidene fluoride with a mass ratio of 50:50 and halloysite modified by the three-step combination of electrodeposition of surface Prussian blue analogue coating - catechol coating deposition - sulfonation were subjected to ion exchange in an aqueous holmium nitrate solution. After washing away the excess ions, they were dissolved in dimethyl sulfoxide to prepare a film-forming solution. After complete dissolution, it was left standing to remove bubbles; the film-forming solution was poured into a petri dish, and under the condition of a magnetic field strength of 4 Tesla in the vertical direction and a temperature of 90 °C, the solvent was evaporated for 35 hours to form a film; the film was acidified to obtain an ion exchange membrane with a through-plane orientation structure.

[0095] Example 14:

[0096] PVC with a ferrocyanide coordination group structure, PMMA, and rectorite modified by a three-step combination of electrodeposition of a surface Prussian blue analogue coating, deposition of a catechol coating, and sulfonation with a mass ratio of 60:20:20 were subjected to ion exchange in an erbium nitrate aqueous solution. After washing away the excess ions, they were dissolved in m-cresol to prepare a film-forming solution. After complete dissolution, the solution was allowed to stand for defoaming. The film-forming solution was poured into a petri dish and evaporated at a temperature of 90 °C for 30 hours in a vertical magnetic field with a magnetic field strength of 5 Tesla to form a film. The film was acidified to obtain an ion exchange membrane with a through-plane orientation structure.

[0097] Example 15:

[0098] Polyvinylcyclohexane with a ferrocyanide coordination group structure and graphene modified by a three-step combination of electrodeposition of a surface Prussian blue analogue coating, deposition of a catechol coating, and sulfonation with a mass ratio of 70:30 were dissolved in a mixed solvent to prepare a film-forming solution. After complete dissolution, the solution was allowed to stand for defoaming. The film-forming solution was poured into a petri dish and evaporated at a temperature of 40 °C for 48 hours in a vertical magnetic field with a magnetic field strength of 5 Tesla to form a film. The film was acidified to obtain an ion exchange membrane with a through-plane orientation structure.

[0099] Furthermore, the mixed solvent in Example 15 is: dimethyl sulfoxide and 3-nonanol with a volume ratio of 65:35, and the boiling point difference under atmospheric pressure is not more than 4 °C.

[0100] Example 16:

[0101] Polyvinylpyridine with a ferrocyanide coordination group structure was dissolved in a mixed solvent to prepare a film-forming solution. After complete dissolution, the solution was allowed to stand for defoaming. The film-forming solution was poured into a petri dish and evaporated at a temperature of 110 °C for 25 hours in a vertical magnetic field with a magnetic field strength of 4 Tesla to form a film. The film was acidified to obtain an ion exchange membrane with a through-plane orientation structure.

[0102] Furthermore, the mixed solvent in Example 16 is: dimethyl sulfoxide and 1,2-butanediol with a volume ratio of 10:90, and the boiling point difference under atmospheric pressure is not more than 4 °C.

[0103] Example 17:

[0104] Polyphenylene ether with a ferrocyanide coordination group structure and graphene oxide modified by a three-step combination of electrodeposition of a surface Prussian blue analogue coating, deposition of a catechol coating, and sulfonation with a mass ratio of 85:15 were dissolved in a mixed solvent to prepare a film-forming solution. After complete dissolution, the solution was allowed to stand for defoaming. The film-forming solution was poured into a petri dish and evaporated at a temperature of 100 °C for 40 hours in a vertical magnetic field with a magnetic field strength of 3 Tesla to form a film. The film was acidified to obtain an ion exchange membrane with a through-plane orientation structure.

[0105] Further, the mixed solvent in Example 17 is: dimethyl sulfoxide and 2-ethylbutyric acid with a volume ratio of 80:20, and the boiling point difference under normal pressure is not more than 4 degrees Celsius.

[0106] Example 18:

[0107] Dissolve polyethylene with a ferrocyanide coordination group structure and boron nitride modified by the three-step combination of electrodeposition of a surface Prussian blue analogue coating, deposition of a catechol coating, and sulfonation with a mass ratio of 60:40 in a mixed solvent to prepare a membrane-forming solution. After complete dissolution, let it stand for defoaming; pour the membrane-forming solution into a petri dish, and under the condition of a vertical magnetic field strength of 4 Tesla and a temperature of 90 °C, evaporate the solvent for 35 hours to form a membrane; perform acidification treatment on the membrane to obtain an ion exchange membrane with a through-surface orientation structure.

[0108] Further, the mixed solvent in Example 18 is: N-methylpyrrolidone and α-phenylethanol with a volume ratio of 50:50, and the boiling point difference under normal pressure is not more than 4 degrees Celsius.

[0109] Example 19:

[0110] Dissolve polyvinylcyclohexane with a ferrocyanide coordination group structure and carbon nitride modified by the three-step combination of electrodeposition of a surface Prussian blue analogue coating, deposition of a catechol coating, and sulfonation with a mass ratio of 99:1 in a mixed solvent to prepare a membrane-forming solution. After complete dissolution, let it stand for defoaming; pour the membrane-forming solution into a petri dish, and under the condition of a vertical magnetic field strength of 5 Tesla and a temperature of 90 °C, evaporate the solvent for 30 hours to form a membrane; perform acidification treatment on the membrane to obtain an ion exchange membrane with a through-surface orientation structure.

[0111] Further, the mixed solvent in Example 19 is: N-methylpyrrolidone and α-phenylethanol with a volume ratio of 30:70, and the boiling point difference under normal pressure is not more than 4 degrees Celsius.

[0112] Example 20:

[0113] Perform ion exchange of polyethylene with a ferrocyanide coordination group structure and montmorillonite modified by the three-step combination of electrodeposition of a surface Prussian blue analogue coating, deposition of a catechol coating, and sulfonation with a mass ratio of 65:35 in an aqueous solution of thulium bromide, wash away the excess ions, and then dissolve it in a mixed solvent to prepare a membrane-forming solution. After complete dissolution, let it stand for defoaming; pour the membrane-forming solution into a petri dish, and under the condition of a vertical magnetic field strength of 4.5 Tesla and a temperature of 60 °C, evaporate the solvent for 45 hours to form a membrane; perform acidification treatment on the membrane to obtain an ion exchange membrane with a through-surface orientation structure.

[0114] Further, the mixed solvent in Example 20 is: N-methylpyrrolidone and 5-methyl-5-nonanol with a volume ratio of 60:40, and the boiling point difference under normal pressure is not more than 4 degrees Celsius.

[0115] Comparative Example 1-1:

[0116] The difference between Comparative Example 1-1 and Example 1 is only that in Comparative Example 1-1, ion replacement before raw material film formation is not carried out, and it is directly dissolved in a film-forming solution prepared from m-cresol and 5-methyl-5-nonanol with a volume ratio of 75:25, and the rest are the same as those in Example 1.

[0117] Comparative Example 1-2:

[0118] The difference between Comparative Example 1-2 and Comparative Example 1-1 is only that in Comparative Example 1-2, the raw material is dissolved in a film-forming solution prepared from m-cresol and 1-methylcyclohexanol with a volume ratio of 75:25, and their boiling points under normal pressure differ by more than 4 degrees Celsius, and the rest are the same as those in Comparative Example 1-1.

[0119] Comparative Example 1-3:

[0120] The difference between Comparative Example 1-3 and Comparative Example 1-2 is only that in Comparative Example 1-3, the raw material is dissolved in a single m-cresol to prepare the film-forming solution, and the rest are the same as those in Comparative Example 1-2.

[0121] Comparative Example 2:

[0122] The difference between Comparative Example 2 and Example 2 is only that in Comparative Example 2, ion replacement before raw material film formation is not carried out, and the rest are the same as those in Example 2.

[0123] Comparative Example 3:

[0124] The difference between Comparative Example 3 and Example 3 is only that in Comparative Example 3, ion replacement before raw material film formation is not carried out, and the rest are the same as those in Example 3.

[0125] Comparative Example 4-1:

[0126] The difference between Comparative Example 4-1 and Example 4 is only that in Comparative Example 4-1, ion replacement before raw material film formation is not carried out, and it is directly dissolved in a film-forming solution prepared from m-cresol and α-phenylethyl alcohol with a volume ratio of 75:25, and the rest are the same as those in Example 4.

[0127] Comparative Example 4-2:

[0128] The difference between Comparative Example 4-2 and Comparative Example 4-1 is that in Comparative Example 4-2, the raw material is dissolved in a film-forming solution prepared from m-cresol and 2-methylcyclohexanol with a volume ratio of 75:25, and their boiling points under normal pressure differ by more than 4 degrees Celsius, and the rest are the same as those in Comparative Example 4-1.

[0129] Comparative Example 4-3:

[0130] The difference between Comparative Example 4-3 and Comparative Example 4-2 is only that in Comparative Example 4-3, the raw materials are dissolved in a single m-cresol to prepare the film-forming solution, and the rest are the same as in Example 4-2.

[0131] Comparative Example 5:

[0132] The difference between Comparative Example 5 and Example 5 is only that in Comparative Example 5, ion replacement before film formation of the raw materials is not carried out, and the rest are the same as in Example 5.

[0133] Comparative Example 6:

[0134] The difference between Comparative Example 6 and Example 6 is only that in Comparative Example 6, ion replacement before film formation of the raw materials is not carried out, and the rest are the same as in Example 6.

[0135] Comparative Example 7-1:

[0136] The difference between Comparative Example 7-1 and Example 7 is only that in Comparative Example 7-1, the raw materials are dissolved in a film-forming solution prepared with N,N-dimethylformamide and 5-methyl-5-nonanol with a volume ratio of 90:10. The boiling points of N,N-dimethylformamide and 5-methyl-5-nonanol differ by more than 4 degrees Celsius under normal pressure, and the rest are the same as in Example 7.

[0137] Comparative Example 7-2:

[0138] The difference between Comparative Example 7-2 and Example 7-1 is only that in Comparative Example 7-2, the raw materials are dissolved in a single N,N-dimethylformamide to prepare the film-forming solution, and the rest are the same as in Example 7-1.

[0139] Comparative Example 8-1:

[0140] The difference between Comparative Example 8-1 and Example 8 is only that in Comparative Example 8-1, the raw materials are dissolved in a film-forming solution prepared with N,N-dimethylformamide and α-phenylethanol with a volume ratio of 60:40. The boiling points of N,N-dimethylformamide and α-phenylethanol differ by more than 4 degrees Celsius under normal pressure, and the rest are the same as in Example 8.

[0141] Comparative Example 8-2:

[0142] The difference between Comparative Example 8-2 and Example 8-1 is only that in Comparative Example 8-2, the raw materials are dissolved in a single N,N-dimethylformamide to prepare the film-forming solution, and the rest are the same as in Example 8-1.

[0143] Comparative Example 9-1:

[0144] The difference between Comparative Example 9-1 and Example 9 is only that in Comparative Example 9-1, ion replacement before film formation of the raw materials is not carried out, and it is directly dissolved in N,N-dimethylacetamide and 2-methylcyclohexanol with a volume ratio of 40:60, and the rest are the same as in Example 9.

[0145] Comparative Example 9-2:

[0146] The difference between Comparative Example 9-2 and Comparative Example 9-1 is only that, in Comparative Example 9-2, the raw materials are dissolved in a film-forming solution prepared from N,N-dimethylacetamide and 3-nonanol with a volume ratio of 40:60, and their boiling points under atmospheric pressure differ by more than 4 °C, and the rest are the same as those in Comparative Example 9-1.

[0147] Comparative Example 9-3:

[0148] The difference between Comparative Example 9-3 and Comparative Example 9-2 is only that, in Comparative Example 9-3, the raw materials are dissolved in a single N,N-dimethylacetamide to prepare a film-forming solution, and the rest are the same as those in Comparative Example 9-2.

[0149] Comparative Example 10:

[0150] The difference between Comparative Example 10 and Example 10 is only that, in Comparative Example 10, ion replacement before film formation of the raw materials is not carried out, and the rest are the same as those in Example 10.

[0151] Comparative Example 11:

[0152] The difference between Comparative Example 11 and Example 11 is only that, in Comparative Example 11, ion replacement before film formation of the raw materials is not carried out, and the rest are the same as those in Example 11.

[0153] Comparative Example 12:

[0154] The difference between Comparative Example 12 and Example 12 is only that, in Comparative Example 12, ion replacement before film formation of the raw materials is not carried out, and the rest are the same as those in Example 12.

[0155] Comparative Example 13:

[0156] The difference between Comparative Example 13 and Example 13 is only that, in Comparative Example 13, ion replacement before film formation of the raw materials is not carried out, and the rest are the same as those in Example 13.

[0157] Comparative Example 14:

[0158] The difference between Comparative Example 14 and Example 14 is only that, in Comparative Example 14, ion replacement before film formation of the raw materials is not carried out, and the rest are the same as those in Example 14.

[0159] Comparative Example 15-1:

[0160] The difference between Comparative Example 15-1 and Example 15 is only that, in Comparative Example 15-1, the raw materials are dissolved in a film-forming solution prepared from dimethyl sulfoxide and 1-methylcyclohexanol with a volume ratio of 65:35, and the boiling points of dimethyl sulfoxide and 1-methylcyclohexanol under atmospheric pressure differ by more than 4 °C, and the rest are the same as those in Example 15.

[0161] Comparative Example 15-2:

[0162] The difference between Comparative Example 15-2 and Example 15 is only that in Comparative Example 15-2, the raw materials are dissolved in a single dimethyl sulfoxide to prepare the membrane-forming solution, and the rest are the same as in Example 15.

[0163] Comparative Example 16-1:

[0164] The difference between Comparative Example 16-1 and Example 16 is only that in Comparative Example 16-1, the raw materials are dissolved in a membrane-forming solution prepared from dimethyl sulfoxide and 2-methylcyclohexanol with a volume ratio of 10:90. The boiling points of dimethyl sulfoxide and 2-methylcyclohexanol differ by more than 4 degrees Celsius under normal pressure, and the rest are the same as in Example 16.

[0165] Comparative Example 16-2:

[0166] The difference between Comparative Example 16-2 and Example 16 is only that in Comparative Example 16-2, the raw materials are dissolved in a single dimethyl sulfoxide to prepare the membrane-forming solution, and the rest are the same as in Example 16.

[0167] Comparative Example 17-1:

[0168] The difference between Comparative Example 17-1 and Example 17 is only that in Comparative Example 17-1, the raw materials are dissolved in a membrane-forming solution prepared from dimethyl sulfoxide and 1-methylcyclohexanol with a volume ratio of 80:20. The boiling points of dimethyl sulfoxide and 1-methylcyclohexanol differ by more than 4 degrees Celsius under normal pressure, and the rest are the same as in Example 17.

[0169] Comparative Example 17-2:

[0170] The difference between Comparative Example 17-2 and Example 17 is only that in Comparative Example 17-2, the raw materials are dissolved in a single dimethyl sulfoxide to prepare the membrane-forming solution, and the rest are the same as in Example 17.

[0171] Comparative Example 18-1:

[0172] The difference between Comparative Example 18-1 and Example 18 is only that in Comparative Example 18-1, the raw materials are dissolved in a membrane-forming solution prepared from N-methylpyrrolidone and 1,2-butanediol with a volume ratio of 50:50. The boiling points of N-methylpyrrolidone and 1,2-butanediol differ by more than 4 degrees Celsius under normal pressure, and the rest are the same as in Example 18.

[0173] Comparative Example 18-2:

[0174] The difference between Comparative Example 18-2 and Example 18 is only that in Comparative Example 18-2, the raw materials are dissolved in a single N-methylpyrrolidone to prepare the membrane-forming solution, and the rest are the same as in Example 18.

[0175] Comparative Example 19-1:

[0176] The difference between Comparative Example 19-1 and Example 19 is only that in Comparative Example 19-1, the raw materials were dissolved in a film-forming solution prepared with N-methylpyrrolidone and 2-ethylbutyric acid in a volume ratio of 30:70, and the boiling points of N-methylpyrrolidone and 2-ethylbutyric acid under normal pressure differ by more than 4 °C, and the rest are the same as those in Example 19.

[0177] Comparative Example 19-2:

[0178] The difference between Comparative Example 19-2 and Example 19 is only that in Comparative Example 19-2, the raw materials were dissolved in a single N-methylpyrrolidone to prepare a film-forming solution, and the rest are the same as those in Example 19.

[0179] Comparative Example 20-1:

[0180] The difference between Comparative Example 20-1 and Example 20 is only that in Comparative Example 20-1, the ion replacement before film formation of the raw materials was not carried out, and it was directly dissolved in a film-forming solution prepared with N-methylpyrrolidone and 5-methyl-5-nonanol in a volume ratio of 60:40, and the rest are the same as those in Example 20.

[0181] Comparative Example 20-2:

[0182] The difference between Comparative Example 20-2 and Comparative Example 20-1 is only that in Comparative Example 20-2, the raw materials were dissolved in a film-forming solution prepared with N-methylpyrrolidone and 2-methylcyclohexanol in a volume ratio of 60:40, and their boiling points under normal pressure differ by more than 4 °C, and the rest are the same as those in Comparative Example 20-1.

[0183] Comparative Example 20-3:

[0184] The difference between Comparative Example 20-3 and Comparative Example 20-2 is only that in Comparative Example 20-3, the raw materials were dissolved in a single N-methylpyrrolidone to prepare a film-forming solution, and the rest are the same as those in Comparative Example 20-2.

[0185] The present invention conducted conductivity tests on the ion exchange membranes prepared in Examples 1-20 and Comparative Examples, and the test results are shown in Table 1.1:

[0186] Table 1.1

[0187]

[0188]

[0189]

[0190]

[0191]

[0192] As known from Table 1.1:

[0193] The degree of orientation of Example 1 is about 2.7 times that of Comparative Example 1-1;

[0194] This shows that ion replacement before the raw materials are dissolved in the mixed solvent can improve the through-plane conductivity and the degree of orientation of the ion exchange membrane.

[0195] The degree of orientation of Comparative Example 1-1 is about 2.3 times that of Comparative Example 1-2;

[0196] This shows that when the boiling points of the mixed solvents differ by no more than 4 °C, the through-plane conductivity and the degree of orientation of the ion exchange membrane can be improved.

[0197] The degree of orientation of Comparative Example 1-2 is almost the same as that of Comparative Example 1-3, but the through-plane conductivity and the in-plane conductivity are both improved;

[0198] This shows that using a mixed solvent to prepare the membrane-forming solution can improve the overall conductivity of the ion exchange membrane.

[0199] The degree of orientation of Example 2 is increased to about 5.1 times that of Comparative Example 2; the degree of orientation of Example 3 is increased to about 3.1 times that of Comparative Example 3; the degree of orientation of Example 5 is increased to about 3.3 times that of Comparative Example 5; the degree of orientation of Example 6 is increased to about 3.2 times that of Comparative Example 6; the degree of orientation of Example 10 is increased to about 2.7 times that of Comparative Example 10; the degree of orientation of Example 11 is increased to about 3.5 times that of Comparative Example 11; the degree of orientation of Example 12 is increased to about 2.6 times that of Comparative Example 12; the degree of orientation of Example 13 is increased to about 2.5 times that of Comparative Example 13; the degree of orientation of Example 14 is increased to about 2.3 times that of Comparative Example 14;

[0200] This shows that ion replacement before preparing the membrane-forming solution can improve the through-plane conductivity and the degree of orientation of the ion exchange membrane.

[0201] The degree of orientation of Example 4 is about 2.9 times that of Comparative Example 4-1;

[0202] This shows that ion replacement before the raw materials are dissolved in the mixed solvent can improve the through-plane conductivity and the degree of orientation of the ion exchange membrane.

[0203] The degree of orientation of Comparative Example 4-1 is about 2.3 times that of Comparative Example 4-2;

[0204] This shows that when the boiling points of the mixed solvents differ by no more than 4 °C, the through-plane conductivity and the degree of orientation of the ion exchange membrane can be improved.

[0205] The degree of orientation of Comparative Example 4-2 is almost the same as that of Comparative Example 4-3, but the conductivities in the through-plane direction and in-plane direction are both increased;

[0206] This indicates that using a mixed solvent to prepare the membrane-forming solution can improve the overall conductivity of the ion exchange membrane.

[0207] The degree of orientation of Example 7 is about 3.4 times that of Comparative Example 7-1; the degree of orientation of Example 8 is about 2.7 times that of Comparative Example 8-1;

[0208] This indicates that when the boiling points of the mixed solvents differ by no more than 4 °C, the conductivity in the through-plane direction and the degree of orientation of the ion exchange membrane can be improved.

[0209] The degree of orientation of Comparative Example 7-1 is almost the same as that of Comparative Example 7-2, but the conductivities in the through-plane direction and in-plane direction are both increased; the degree of orientation of Comparative Example 8-1 is almost the same as that of Comparative Example 8-2, but the conductivities in the through-plane direction and in-plane direction are both increased;

[0210] This indicates that using a mixed solvent to prepare the membrane-forming solution can improve the overall conductivity of the ion exchange membrane.

[0211] The degree of orientation of Example 9 is about 4.0 times that of Comparative Example 9-1;

[0212] This indicates that performing ion replacement on the raw materials before dissolving them in the mixed solvent can improve the conductivity in the through-plane direction and the degree of orientation of the ion exchange membrane.

[0213] The degree of orientation of Comparative Example 9-1 is about 2.2 times that of Comparative Example 9-2;

[0214] This indicates that when the boiling points of the mixed solvents differ by no more than 4 °C, the conductivity in the through-plane direction and the degree of orientation of the ion exchange membrane can be improved.

[0215] The degree of orientation of Comparative Example 9-2 is almost the same as that of Comparative Example 9-3, but the conductivities in the through-plane direction and in-plane direction are both increased;

[0216] This indicates that using a mixed solvent to prepare the membrane-forming solution can improve the overall conductivity of the ion exchange membrane.

[0217] The degree of orientation of Example 15 is about 4.6 times that of Comparative Example 15-1; the degree of orientation of Example 16 is about 3.9 times that of Comparative Example 16-1; the degree of orientation of Example 17 is about 3.0 times that of Comparative Example 17-2; the degree of orientation of Example 18 is about 2.9 times that of Comparative Example 18-2; the degree of orientation of Example 19 is about 2.9 times that of Comparative Example 19-2;

[0218] This indicates that when the boiling points of the mixed solvents differ by no more than 4 °C, the conductivity in the through-plane direction and the degree of orientation of the ion exchange membrane can be improved.

[0219] The degree of orientation of Comparative Example 15-1 is almost the same as that of Comparative Example 15-2, but the conductivity in the through-plane direction and in-plane direction both increase; the degree of orientation of Comparative Example 16-1 is almost the same as that of Comparative Example 16-2, but the conductivity in the through-plane direction and in-plane direction both increase; the degree of orientation of Comparative Example 17-1 is almost the same as that of Comparative Example 17-2, but the conductivity in the through-plane direction and in-plane direction both increase; the degree of orientation of Comparative Example 18-1 is almost the same as that of Comparative Example 18-2, but the conductivity in the through-plane direction and in-plane direction both increase; the degree of orientation of Comparative Example 19-1 is almost the same as that of Comparative Example 19-2, but the conductivity in the through-plane direction and in-plane direction both increase;

[0220] This indicates that using a mixed solvent to prepare the membrane-forming solution can improve the overall conductivity of the ion exchange membrane.

[0221] The degree of orientation of Example 20 is about 2.8 times that of Comparative Example 20-1;

[0222] This indicates that performing ion replacement on the raw materials before dissolving them in the mixed solvent can improve the conductivity in the through-plane direction and the degree of orientation of the ion exchange membrane.

[0223] The degree of orientation of Comparative Example 20-1 is about 1.6 times that of Comparative Example 20-2;

[0224] This indicates that when the boiling points of the mixed solvents differ by no more than 4 °C, the conductivity in the through-plane direction and the degree of orientation of the ion exchange membrane can be improved.

[0225] The degree of orientation of Comparative Example 20-2 is almost the same as that of Comparative Example 20-3, but the conductivity in the through-plane direction and in-plane direction both increase;

[0226] This indicates that using a mixed solvent to prepare the membrane-forming solution can improve the overall conductivity of the ion exchange membrane.

[0227] To deeply elaborate on the reasons for the above-mentioned performance differences, including the influence of ion replacement before membrane formation and the influence of using a mixed solvent with a boiling point difference of no more than 4 °C under normal pressure conditions (including two aspects: (1) the influence from using a single solvent to using a mixed solvent; (2) the influence from using a mixed solvent with a boiling point difference greater than 4 °C under normal pressure conditions to using a mixed solvent with a boiling point difference of no more than 4 °C under normal pressure conditions), further characterization was carried out on the membrane-forming solution and the prepared ion exchange membrane. In the present invention, in each example and each comparative example using the same membrane-forming raw materials and the same magnetic field strength, the structural performance data of the membrane-forming solution and the prepared membranes are shown in Table 1.2:

[0228] Among them, the magnetization intensity of the film-forming solution was measured using a vibrating sample magnetometer at 1 Tesla and 25 °C; the aggregation size and orientation regularity of the hydrophilic phase of the film were measured using small-angle X-ray scattering at 50% relative humidity and 25 °C. The aggregation size of the hydrophilic phase of the film was calculated from the peak position of small-angle X-ray scattering, and the ratio of the peak height to the full width at half maximum of small-angle X-ray scattering characterized the orientation regularity of the hydrophilic phase of the film.

[0229] Table 1.2

[0230]

[0231]

[0232]

[0233]

[0234]

[0235] As can be seen from Table 1.2, in the examples and comparative examples using the same film-forming raw materials and magnetic field intensity, ion replacement before film formation can significantly increase the magnetization intensity of the film-forming solution.

[0236] A mixed solvent with a boiling point difference of no more than 4 °C under atmospheric pressure can significantly increase the aggregation size of the hydrophilic phase of the film and the orientation regularity of the hydrophilic phase.

[0237] The role of ion replacement before film formation in the present invention is as follows:

[0238] Compared with the ions originally carried by the polymer or filler, the replaced ions can enhance the magnetization intensity of the film-forming solution, and the magnetic response ability is greatly improved, so that an ion exchange membrane with a higher degree of through-plane orientation can be prepared under the condition of using the same film-forming raw materials and the same magnetic field intensity. If ion replacement is not carried out before film formation using an ion replacement agent, the magnetization intensity of the film-forming solution is low, and the orientation degree of the ion exchange membrane prepared under the condition of using the same film-forming raw materials and the same magnetic field intensity is low, and the advantage that the ionic conductivity is concentrated in the through-plane direction is not obvious.

[0239] The role of using a mixed solvent with a boiling point difference of no more than 4 °C under atmospheric pressure lies in two aspects:

[0240] On the one hand, compared with a single solvent, there are certain polarity differences between the two solvent components of the mixed solvent. One solvent component is more affinity with the hydrophilic phase with ion transport ability in the film-forming raw material, and the other solvent component is more affinity with the hydrophobic phase without ion transport ability in the film-forming raw material. Therefore, the mixed solvent can promote the hydrophilic-hydrophobic phase separation of the raw materials in the film-forming solution, making the aggregation size of the hydrophilic phase with ion transport ability larger, and the size of the oriented transport channels formed on the permeation surface under magnetic field conditions is also larger, which is more conducive to the smooth transport of ions.

[0241] On the other hand, the condition that the boiling points of the mixed solvent differ by no more than 4 degrees Celsius under normal pressure makes the mixed solvent have a similar evaporation rate during the evaporation process, ensuring that the two solvent components evaporate completely at basically the same time. If a mixed solvent with a large difference in boiling points is used, after the mixed solvent helps to generate hydrophilic-hydrophobic phase separation, one solvent component will evaporate completely first during the film-forming process, leaving a relatively high content of the other solvent component. At this time, it becomes a single solvent, which will destroy the hydrophilic-hydrophobic phase separation generated by the mixed solvent in the initial stage of film formation, resulting in the difficulty of maintaining the large-sized and regular oriented transport channels formed by the mixed solvent until the final film formation, and there will be size shrinkage and reduced regularity. Therefore, the condition that the boiling points of the mixed solvent differ by no more than 4 degrees Celsius under normal pressure can better maintain the hydrophilic-hydrophobic phase separation generated by the mixed solvent during the entire film-forming process and the large size and regularity of the obtained oriented transport channels.

[0242] These two effects can improve the ion transport performance advantage of the finally prepared ion exchange membrane in the permeation surface direction.

[0243] In summary, compared with the general film-forming method, the present invention adopts the treatment technology of ion replacement before film formation, a mixed solvent with a boiling point difference of no more than 4 degrees Celsius under normal pressure to prepare the film-forming solution, or a combination of the two. Under the same film-forming raw materials and the same magnetic field strength, it can enhance the magnetic response ability of the film-forming solution, and improve the aggregation size and orientation regularity of the hydrophilic phase during the entire film-forming process. This method breaks through the limitation of only synthesizing polymers or fillers with electric field or magnetic field responsiveness and forming films under electric field or magnetic field conditions, comprehensively considers and optimizes important factors such as ions and solvents in the entire film-forming system and process, greatly improves the orientation degree of the ion exchange membrane, and obtains more significant ion transport performance benefits in the permeation surface direction.

[0244] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an ion exchange membrane having a permeable surface oriented structure, characterized in that: The following steps are involved: S001: Using polymer A having a magnetically responsive structure alone or using one of the following compositions, ion replacement is performed in an ion replacement agent aqueous solution before film formation, and after washing away excess ions, the mixture is dissolved in a single solvent to prepare a film-forming solution; wherein the ion replacement agent is one of sodium molybdate, sodium tungstate, potassium tetrafluoroborate, potassium hexafluorophosphate, potassium hexafluoroantimonate, lithium bis(trifluoromethanesulfonyl imide), gadolinium nitrate, terbium chloride, dysprosium chloride, holmium nitrate, erbium nitrate, and thulium bromide; and the single solvent is one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, and m-cresol; The composition comprises composition ① and / or composition ②, wherein: The composition ① is a combination of any two of the polymer B, the polymer A having a magnetic responsive structure, and the filler a having a magnetic responsive structure; The composition ② is a combination of polymer B, polymer A having a magnetic responsive structure and filler a having a magnetic responsive structure; S002: pour the film-making solution into a culture dish, and evaporate the solvent for 12-48 hours to form a film under the conditions of a vertical magnetic field strength of 0.001-5 Tesla and a temperature of 40-120°C; S003: The formed membrane is subjected to alkalization or acidification treatment to obtain an ion exchange membrane having a permeable surface oriented structure.

2. The method for preparing an ion exchange membrane having a permeable surface oriented structure according to claim 1, characterized in that: In step S001, the membrane-making solution can also be prepared by the following steps: A polymer A having a magnetically responsive structure is used alone or one of the following compositions is used to perform ion replacement in an ion replacement agent aqueous solution before film formation, and after washing away excess ions, it is dissolved in a mixed solvent with a boiling point difference of no more than 4 degrees Celsius under normal pressure to prepare a film-forming solution; wherein the ion replacement agent is one of sodium molybdate, sodium tungstate, potassium tetrafluoroborate, potassium hexafluorophosphate, potassium hexafluoroantimonate, lithium bis(trifluoromethanesulfonyl imide), gadolinium nitrate, terbium chloride, dysprosium chloride, holmium nitrate, erbium nitrate, and thulium bromide; The composition comprises composition ① and / or composition ②, wherein: The composition ① is a combination of any two of the polymer B, the polymer A having a magnetic responsive structure, and the filler a having a magnetic responsive structure; The composition ② is a combination of polymer B, polymer A having a magnetic responsive structure and filler a having a magnetic responsive structure.

3. The method for preparing an ion exchange membrane having a permeable surface oriented structure according to claim 1, characterized in that: The polymer main chain in the polymer A is one of polyimide, polyamide, polyetheretherketone, polysulfone, polyethersulfone, polytetrafluoroethylene, polydimethylsiloxane, polystyrene, polybenzimidazole, polyphenylene ether, polyethylene, polyvinyl chloride, polyvinylpyridine or polyvinylcyclohexane; the magnetic responsive structure of the polymer A is one of ferrocenium cation group, cobaltocene cation group, nickelocene cation group and ferrocyanide coordination group.

4. The method for preparing an ion exchange membrane having a permeable surface oriented structure according to claim 1, characterized in that: The filler a is one of modified iron oxide particles, modified erbium oxide particles, modified carbon nanotubes, modified halloysite, modified rectorite, modified montmorillonite, modified silicon dioxide, modified titanium dioxide, modified graphene, modified graphene oxide, modified boron nitride or modified nitrogen carbide; the magnetic responsive structure of the filler a is iron oxide, erbium oxide or a Prussian blue analogue.

5. The method for preparing an ion exchange membrane having a permeable surface oriented structure according to claim 1, characterized in that: The polymer B is one of polyimide, polysulfone, polyethersulfone, polystyrene, polyphenylene sulfide, polyvinylpyridine, polypropylene, polyacrylonitrile, polyphosphazene, polyvinylidene fluoride or polymethyl methacrylate.

6. The method for preparing an ion exchange membrane having a permeable surface oriented structure according to claim 1, characterized in that: When the polymer A and polymer B are used to prepare the membrane-making solution, the mass ratio is (1-99): (1-99); when the polymer A and filler a are used to prepare the membrane-making solution, the mass ratio is (50-99): (1-50); when the polymer B and filler a are used to prepare the membrane-making solution, the mass ratio is (50-99): (1-50); when the polymer A, polymer B and filler a are used to prepare the membrane-making solution, the mass ratio is (1-98): (1-98): (1-50).

7. The method for preparing an ion exchange membrane having a permeable surface oriented structure according to claim 2, characterized in that: The mixed solvent with a boiling point difference of no more than 4 degrees Celsius under normal pressure conditions is a group selected from N,N-dimethylformamide and 1-methylcyclohexanol, N,N-dimethylacetamide and 2-methylcyclohexanol, dimethyl sulfoxide and 3-nonanol, dimethyl sulfoxide and 1,2-butanediol, dimethyl sulfoxide and 2-ethylbutyric acid, N-methylpyrrolidone and 5-methyl-5-nonanol, N-methylpyrrolidone and α-phenylethanol, m-cresol and 5-methyl-5-nonanol, m-cresol and α-phenylethanol, and the volume ratio of the two solvent components in the mixed solvent is (10-90): (10-90).

8. The method for preparing an ion exchange membrane having a permeable surface oriented structure according to claim 4, characterized in that: The modification is surface quaternization, or a three-step combination of surface Prussian blue analog coating electrodeposition-catechol coating deposition-sulfonation.

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