CN117024840A

CN117024840A - Surface modified microporous membrane and preparation method and application thereof

Info

Publication number: CN117024840A
Application number: CN202310988911.9A
Authority: CN
Inventors: 马亚敏; 常磊; 张泽天; 刘卫霞; 张亚欢; 李蕴熙; 方亮; 刘贝贝; 贾雯迪; 邓颖姣; 陈富斌; 黄舜; 赖文文; 李道喜; 刘昊; 刚直
Original assignee: Foshan Lvdong Hydrogen Energy Technology Co ltd; Wuhan Lvdong Hydrogen Energy Technology Co ltd; Spic Hydrogen Energy Technology Development Co Ltd
Current assignee: Foshan Lvdong Hydrogen Energy Technology Co ltd; Wuhan Lvdong Hydrogen Energy Technology Co ltd; Spic Hydrogen Energy Technology Development Co Ltd
Priority date: 2023-08-07
Filing date: 2023-08-07
Publication date: 2023-11-10

Abstract

The invention belongs to the field of high polymer materials, and particularly relates to a surface modified microporous membrane, and a preparation method and application thereof. The embodiment of the invention discloses a preparation method of a surface modified microporous membrane, which comprises the following steps: (1) preparing a skeleton polymer material into a microporous membrane; (2) Compounding a functional material to the surface of the microporous membrane by a surface modification method; wherein the functional material comprises at least one of a functionalized metal oxide or a coordination polymer. The functional material is utilized to carry out surface modification on the microporous membrane, a laboratory miniaturized preparation technology and a mature existing industrial production technology can be adopted, the requirements of research and industrial production application are met, and the prepared surface modified microporous membrane has free radical quenching capability and certain oxidation resistance and is wide in application range.

Description

Surface modified microporous membrane and preparation method and application thereof

Technical Field

The invention belongs to the field of high polymer materials, and particularly relates to a surface modified microporous membrane, and a preparation method and application thereof.

Background

The microporous membrane is a film with the aperture of 5 nm-1 mm, and the modification of the microporous membrane can improve the existing performance or endow the microporous membrane with the performance. The application performance of the microporous membrane can be improved by modifying the microporous membrane material by using the functional material, and the application field is expanded. The functional material is a common microporous membrane modification method for carrying out surface modification on the microporous membrane prepared by the skeleton polymer material.

The microporous membrane surface modification method is various and mature in technology, and can effectively improve the existing performance of the microporous membrane or endow the microporous membrane with new functions. The microporous membrane is used as the enhancement layer for the composite ion exchange membrane, and the surface modification direction mainly improves the hydrophilicity and the surface energy of the surface of the microporous membrane, so that the wettability of the microporous membrane by the ion exchange resin dispersion liquid is improved, and the filling degree of the ion exchange resin in the pores of the microporous membrane after the composite ion exchange membrane is formed is improved.

Disclosure of Invention

The present invention has been made based on the findings and knowledge of the inventors regarding the following facts and problems:

in the prior art, microporous membranes are applied to composite ion exchange membranes as reinforcing layers for improving the durability of the ion exchange membranes, but the existing method is to add radical quenchers to ion exchange membrane resins or devices loaded at adjacent positions of the ion exchange membranes, thereby reducing the content of hydroxyl radicals in the ion exchange membranes and improving the chemical durability of the ion exchange membranes. The existing method leads to that the mass content and the volume content of the free radical quencher in the microporous membrane area are lower than those in other areas, and the specific surface area of the ion exchange resin in the area is large, and the hydroxyl free radical sites are more, so that the chemical durability is not improved.

The present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, the embodiment of the invention provides a preparation method of the surface modified microporous membrane, compared with an unmodified microporous membrane, the surface energy of the surface modified microporous membrane prepared by the method is lower, the hydrophilicity is better, and the loaded functional material can be used as a free radical quencher and an antioxidant, when the surface modified microporous membrane is compounded with ion exchange resin to prepare a composite ion exchange membrane, the better hydrophilicity of the surface modified microporous membrane is beneficial to the infiltration and filling of the resin, the functional material improves the chemical durability of the composite ion exchange membrane, and the comprehensive performance of the composite ion exchange membrane is effectively improved.

The preparation method of the surface modified microporous membrane comprises the following steps:

(1) Preparing a skeleton polymer material into a microporous membrane;

(2) Compounding a functional material to the surface of the microporous membrane by a surface modification method; wherein the functional material comprises at least one of a functionalized metal oxide or a coordination polymer.

The preparation method of the surface modified microporous membrane provided by the embodiment of the invention has the advantages and technical effects that 1, the method provided by the embodiment of the invention utilizes the functional material to carry out surface modification on the microporous membrane, and can adopt a laboratory miniaturized preparation technology and a mature existing industrial production technology to meet the requirements of research and industrial production application; 2. the surface modified microporous membrane prepared by the method provided by the embodiment of the invention has better hydrophilicity and higher surface energy, is more beneficial to the infiltration of ion exchange resin dispersion liquid and the filling of ion exchange resin, and is beneficial to the processing of the composite ion exchange membrane and the improvement of comprehensive performance; 3. the surface modified microporous membrane prepared by the method provided by the embodiment of the invention can be applied to the fields of filter materials, sealing materials, textile materials, battery diaphragms and the like, and has a wide application range.

In some embodiments, in the step (1), the skeletal polymeric material comprises at least one of a polyolefin and an aromatic polymer, preferably the skeletal polymeric material is a polyolefin, preferably at least one of a fluorinated polyolefin and a non-fluorinated polyolefin;

wherein the fluorinated polyolefin comprises at least one of a fluorinated olefin monomer homopolymer, a plurality of fluorinated olefin monomer copolymers, a fluorinated olefin monomer and non-fluorinated olefin monomer copolymer, a fluorinated olefin monomer and a perfluoroalkyl vinyl ether copolymer;

the structural formula of the fluorine-containing olefin monomer is as follows:wherein R is ₆ Selected from F or C1-C6 perfluoroalkyl, preferably F, CF ₃ 、C ₂ F ₅ Or C ₃ F ₇ More preferably F or CF ₃ ；R ₇ 、R ₈ And R is ₉ A perfluoroalkyl group selected from H, F, cl, br, I or C1 to C6, preferably H, F, cl, br, I, more preferably H, F or Cl; further preferably, the fluoroolefin monomer comprises at least one of hexafluoropropylene, tetrafluoroethylene, trifluoroethylene, 1-difluoroethylene, 1, 2-difluoroethylene, vinyl fluoride, chlorotrifluoroethylene, 1-chloro-1, 2-difluoroethylene, 1-chloro-2-fluoroethylene, 1-chloro-1-fluoroethylene, 1-dichloro-2, 2-difluoroethylene, 1, 2-dichloro-1, 2-difluoroethylene, 1-dichloro-2-fluoroethylene, 1, 2-dichloro-fluoroethylene or trichlorofluoroethylene; preferably at least one of hexafluoropropylene, tetrafluoroethylene, trifluoroethylene, 1-difluoroethylene, 1, 2-difluoroethylene, vinyl fluoride, chlorotrifluoroethylene, preferably hexafluoropropylene, tetrafluoroethylene, trifluoroethylene, 1-difluoroethylene, 1, 2-difluoroethylene, vinyl fluoride, 1-chloro-1, 2-difluoroethylene, 1-chloro-2-fluoroethylene, 1-chloro-1-fluoroethylene or chlorotrifluoroethylene, more preferably at least one of hexafluoropropylene, tetrafluoroethylene, trifluoroethylene, 1-difluoroethylene, vinyl fluoride or chlorotrifluoroethylene;

The non-fluoroolefin monomer comprises at least one of vinyl chloride, norbornene, or C1-C8 mono-olefin, preferably at least one of ethylene, propylene, vinyl chloride, norbornene, or 1-octene, more preferably at least one of ethylene or propylene;

the perfluoroalkyl vinyl ether comprises at least one of perfluoromethyl vinyl ether, perfluoroethyl vinyl ether or perfluoropropyl vinyl ether.

In some embodiments, the fluorinated polyolefin comprises at least one of polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-propylene copolymer, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene-ethylene copolymer, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, polyvinyl fluoride, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer;

the non-fluorinated polyolefin comprises at least one of polyethylene, polypropylene, ethylene-propylene copolymer or ethylene-1-octene copolymer.

In some embodiments, the functionalized metal oxide comprises at least one of a functionalized metal oxide of a lanthanide metal, iron, aluminum, manganese, zirconium; preferably, at least one of functionalized metal cerium oxide and functionalized metal manganese oxide is included; more preferably, at least one of phosphorylated ceria, sulfonated ceria, phosphorylated manganese dioxide and sulfonated manganese dioxide is included.

In some embodiments, the functionalized metal oxide is a nanoscale functionalized metal oxide, preferably having a particle size of less than 100nm, preferably less than 80nm.

In some embodiments, the metal ion of the coordination polymer ligand center comprises at least one of a lanthanide metal ion, a zirconium ion, an iron ion, an aluminum ion, a manganese ion, and a zinc ion, preferably the metal ion comprises at least one of a zirconium ion, a manganese ion, and a cerium ion, preferably Ce ³⁺ 、Ce ⁴⁺ 、Mn ²⁺ 、Mn ³⁺ 、Mn ⁴⁺ At least one of them.

In some embodiments, the coordination polymer comprises at least one of a coordination polymer of one-dimensional structure, a coordination network of two-dimensional structure, and a coordination network of three-dimensional structure;

wherein the organic ligand of the coordination polymer comprises at least one of sulfonic acid organic ligand and carboxylic acid organic ligand, preferably the organic ligand of the coordination polymer comprises at least one of ethylenediamine tetraacetic acid disodium salt, N- (4-benzoate) iminodiacetic acid, (5-ethoxycarbonyl-6-phenyl-1, 6-dihydropyrimidin-2-one-4-yl) methanesulfonic acid, R-2- (4- (4-carboxybenzyloxy) phenoxy) propionic acid, (5-ethoxycarbonyl-6-bromophenyl-1, 6-dihydropyrimidin-2-one-4-yl) methanesulfonic acid, 1-ferrocenedicarboxylic acid, (5-ethoxycarbonyl-6-methyl-1, 6-dihydropyrimidin-2-one-4-yl) methanesulfonic acid, 1, 10-phenanthroline-2, 9-dicarboxylic acid, (5-ethoxycarbonyl-6-hydrogen-1, 6-dihydropyrimidin-2-one-4-yl) methanesulfonic acid, 5-aminopentane-isophthalic acid and pivalic acid.

In some embodiments, the coordination polymer of one-dimensional structure, coordination network of two-dimensional structure, and coordination network of three-dimensional structure have a unit cell volume ofPreferential +.>More preferably +.>

In some embodiments, the coordination polymer comprises at least one of a two-dimensional porous MOF and a three-dimensional porous MOF,

wherein the two-dimensional porous MOF or the three-dimensional porous MOF has a particle size of 30 to 300nm and a BET specific surface area of 120 to 2200m ² Per gram, the micropore volume is 0.1-0.9 cm ³ /g；

Preferably, the organic ligands in the coordination polymer comprise carboxylic acid-based organic ligands;

further preferably, the carboxylic acid organic ligand comprises at least one of a dicarboxylic acid organic ligand, a tricarboxylic acid organic ligand, a tetracarboxylic acid organic ligand, or a sulfonic acid functionalized diacid organic ligand;

more preferably, the di-, tri-or tetracarboxylic organic ligands comprise at least one of 2,2' thiodicarboxylic acid, 1,3, 5-tribenzoyl benzene, 2' dithiodicarboxylic acid, 3, 6-benzobutane dicarboxylic acid, 1, 4-phthalic acid, 4'4 "-tricarboxylic triphenylamine, 2, 6-naphthalene dicarboxylic acid, 2,4, 6-tris (4-carboxyphenyl) -1,3, 5-triazine, 4' -biphthalic acid, benzene-1, 2,4, 5-tetracarboxylic acid, naphthalene-1, 4-dicarboxylic acid, naphthalene-2, 3,6, 7-tetracarboxylic acid, 4,5,9, 10-tetrahydropyrene-2, 7-dicarboxylic acid, [1,1' -biphenyl ] -3,3', 5' -tetracarboxylic acid, pyrene-2, 7-dicarboxylic acid, 4',5' -bis (4-carboxyphenyl) - [1,1':2', 1' -terphenyl ] -4,4" -dicarboxylic acid, [1,1' - [ 4', 4' - [ 4,4' - [1, 4' -biphenyl ] -4, 6, 7-tetracarboxylic acid, [1, 3', 4' -tetracarboxylic acid, ",4, 5' -biphenyl ] -3, 5' -tetracarboxylic acid,";

More preferably, the sulfonic acid functionalized dicarboxylic acid organic ligand comprises at least one of 2-sulfonic acid terephthalic acid, 3, 7-disulfonaphthyl-2, 6-dicarboxylic acid, 5-sulfonic isophthalic acid, 4, 8-disulfonaphthyl-2, 6-dicarboxylic acid, 2, 5-disulfonic terephthalic acid, 3 '-disulfo- [1,1' -biphenyl ] -4,4 '-dicarboxylic acid, 5, 7-disulfonaphthyl-1, 4-dicarboxylic acid, 4-sulfonic acid-4' 4 "-dicarboxylic acid triphenylamine, 6-sulfenane-1, 4-dicarboxylic acid, [1,1 '-biphenyl ] -4' -sulfonic acid-3, 5-dicarboxylic acid.

In some embodiments, in step (2), the method of surface modification comprises at least one of a surface coating method, a composite surface coating method, a surface deposition method, a surface in-situ growth coating method, and a hydrothermal method.

The embodiment of the invention also provides a surface modified microporous membrane, which is prepared by adopting the method.

The surface modified microporous membrane provided by the embodiment of the invention has the advantages and technical effects that 1, in the embodiment of the invention, the surface modified microporous membrane has free radical quenching capability and a certain oxidation resistance, and can be applied to the filtration and separation fields with special requirements; 2. in the embodiment of the invention, the surface modified microporous membrane has better hydrophilicity and higher surface energy, is more beneficial to the infiltration of ion exchange resin dispersion liquid and the filling of ion exchange resin, and is beneficial to the processing and the improvement of the comprehensive performance of the composite ion exchange membrane.

The embodiment of the invention also provides application of the surface modified microporous membrane in filter materials, sealing materials, textile materials and battery diaphragms.

The embodiment of the invention also provides a composite ion exchange membrane, which comprises the surface modified microporous membrane.

The composite ion exchange membrane provided by the embodiment of the invention has the advantages and technical effects that 1, in the embodiment of the invention, the content of the free radical quencher in the composite region of the microporous membrane and the ion exchange resin of the composite ion exchange membrane is controllable, so that the durability of the composite ion exchange membrane is enhanced; 2. in the embodiment of the invention, the microporous membrane improved by the hydrophilic functional material is beneficial to the infiltration of the ion exchange resin, improves the filling degree of the ion exchange resin in the microporous membrane, has better composite effect, ensures that the composite ion exchange membrane has better comprehensive performance and is convenient to apply in the related fields.

The embodiment of the invention also provides a preparation method of the composite ion exchange membrane, which comprises the following steps:

(a) Dispersing ion exchange resin in a forming solvent to obtain ion exchange resin dispersion;

(b) Coating the ion exchange membrane resin dispersion liquid prepared in the step (a) on the surface of the filling modified microporous membrane to obtain a prefabricated composite ion exchange membrane;

(c) And (3) drying the prefabricated composite ion exchange membrane prepared in the step (b) to obtain the composite ion exchange membrane.

The preparation method of the composite ion exchange membrane provided by the embodiment of the invention has the advantages and technical effects that 1, the method of the embodiment of the invention can improve the binding force between the ion exchange resin and the filling modified microporous membrane, and the prepared composite ion exchange membrane has more stable performance; 2. the method provided by the embodiment of the invention is simple and easy to operate, has high production efficiency, and is convenient for popularization and application in industrial production.

The embodiment of the invention also provides application of the composite ion exchange membrane in fuel cell ion exchange membranes, ion exchange membranes for hydrogen production by water electrolysis, flow battery membranes, chlor-alkali industrial membranes, electrodialysis membranes or osmosis membranes.

Drawings

FIG. 1 is an image of contact angles of MF-1 prepared in example 3, MF-2 prepared in example 4, MF-12 prepared in example 10, MF-17 prepared in example 15, MF-27 prepared in example 17, and e-PTFE-1;

FIG. 2 is a DSC temperature rise profile of MF-1 and e-PTFE-1 prepared in example 3;

FIG. 3 is a surface SEM image of MF-12 and e-PTFE-1 prepared in example 10;

FIG. 4 is a graph of the power density of PEM-2 produced in example 19 and D-PEM-2 produced in comparative example 1.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.

The preparation method of the surface modified microporous membrane provided by the embodiment of the invention comprises the following steps:

(1) Preparing a skeleton polymer material into a microporous membrane;

The preparation method of the surface modified microporous membrane provided by the embodiment of the invention utilizes the functional material to carry out surface modification on the microporous membrane, and can adopt a laboratory miniaturized preparation technology and a mature existing industrial production technology to meet the requirements of research and industrial production application; the prepared surface modified microporous membrane has better hydrophilicity and higher surface energy, is more beneficial to the infiltration of ion exchange resin dispersion liquid and the filling of ion exchange resin, and is beneficial to the processing of the composite ion exchange membrane and the improvement of comprehensive performance; the prepared surface modified microporous membrane can be applied to the fields of filter materials, sealing materials, textile materials, battery diaphragms and the like, and has wide application range.

In some embodiments, preferably, in the step (1), the skeletal polymeric material comprises at least one of a polyolefin and an aromatic polymer, preferably, the skeletal polymeric material is a polyolefin, preferably at least one of a fluorinated polyolefin and a non-fluorinated polyolefin;

Further preferably, the fluoroolefin includes at least one of Polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-propylene copolymer, ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene-ethylene copolymer, polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer (THV), polyvinyl fluoride (PVF), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE); preferably at least one of PTFE, FEP, ETFE, PVDF, PVF, PFA, PCTFE, ECTFE; more preferably at least one of PTFE, PEP, ETFE, PVDF, PVF, PFA, ECTFE;

The non-fluorinated polyolefin includes at least one of polyethylene, polypropylene, ethylene-propylene copolymer, or ethylene-1-octene copolymer (PEO).

In some embodiments, preferably, the aromatic polymer comprises at least one of a polyarylether polymer, a polysulfone polymer, a polybenzimidazole polymer, a polyaramid polymer, a polyimide polymer, a polynitrile polymer, and a polyarylether nitrile polymer; preferably comprises at least one of polyaryletherketone, polysulfone, polyethersulfone ketone, polybenzimidazole, polyaramid, polyimide and polyetheretherketone; more preferably at least one of polyaryletherketone, polysulfone, polyethersulfone ketone, polyaramid and polyimide.

In some embodiments, preferably, in the step (1), the preparation method of the microporous membrane includes at least one of a nuclear track etching, a micro-nano process, a stretching method, a dissolution method, a sintering method, a phase inversion method (including a solvent evaporation method, a water vapor inhalation method, a thermally induced phase separation method, a non-solvent phase separation method, etc.), a membrane splitting method, and an electrospinning method. Further preferably, the preparation method of the microporous membrane includes at least one of a stretching method, a dissolution method, and a phase inversion method.

In some embodiments, preferably, the functionalized metal oxide comprises at least one of a functionalized metal oxide of lanthanide metal, iron, aluminum, manganese, zirconium; preferably, at least one of functionalized metal cerium oxide and functionalized metal manganese oxide is included; more preferably, at least one of phosphorylated ceria, sulfonated ceria, phosphorylated manganese dioxide and sulfonated manganese dioxide is included.

In some embodiments, the metal species in the functionalized metal oxide are preferred, such metals having higher free radical quenching efficiency; the functionalized metal oxide containing manganese or cerium has highest free radical quenching efficiency, can realize higher free radical quenching capacity with smaller content, and still has extremely strong free radical quenching capacity after being converted into other compounds under the environmental effect.

In some embodiments, preferably, the functionalized metal oxide is a nanoscale functionalized metal oxide, preferably having a particle size of less than 100nm, preferably less than 80nm. Further preferably, the functionalized metal oxide has a particle size of less than 50nm.

In embodiments of the present invention, it is preferred that the functionalized metal oxide be nano-sized particles to facilitate uniform dispersion thereof in the microporous membrane.

In some embodiments, preferably, the metal ion of the coordination polymer ligand center comprises at least one of lanthanide metal ion, zirconium ion, iron ion, aluminum ion, manganese ion, and zinc ion, preferably, the metal ion comprises at least one of zirconium ion, manganese ion, and cerium ion, preferably, ce ³⁺ 、Ce ⁴⁺ 、Mn ²⁺ 、Mn ³⁺ 、Mn ⁴⁺ At least one of them. Further preferably, the metal ion of the coordination polymer ligand center comprises Ce ³⁺ 、Ce ⁴⁺ At least one of them.

In the embodiment of the invention, the free radical quenching effect of the coordination polymer mainly depends on metal ions of coordination centers, and preferable coordination center ions have better free radical quenching effect, wherein manganese ions and cerium ions have strongest free radical quenching effect, and cerium ions have better effect; since too high a content of coordination polymer results in a drastic decrease in uniformity and mechanical strength of the microporous membrane, the content of coordination polymer in the modified microporous membrane is limited, and cerium ion is selected as coordination center ion to provide the coordination polymer with high free radical quenching ability at a proper content.

In some embodiments, preferably, the coordination polymer includes at least one of a coordination polymer of one-dimensional structure, a coordination network of two-dimensional structure, and a coordination network of three-dimensional structure;

Wherein the organic ligand of the coordination polymer comprises at least one of sulfonic acid organic ligand and carboxylic acid organic ligand, preferably the organic ligand of the coordination polymer comprises at least one of the following:

in some embodiments, it is preferred that the unit cell volume of the one-dimensional structured coordination polymer, two-dimensional structured coordination network, and three-dimensional structured coordination network isPreferential +.>More preferably

In the embodiment of the invention, the unit cell volume of the coordination polymer is optimized, the dispersion of the coordination polymer in the resin is facilitated, and the prepared surface modified microporous membrane has better performance.

In the embodiments of the present invention, the coordination polymer is preferably treated to 1 to 1000nm, preferably 2 to 500nm, more preferably 2 to 100nm, still more preferably from 3 to 50nm by grinding and/or ball milling.

In some embodiments, preferably, the coordination polymer comprises at least one of a two-dimensional porous MOF and a three-dimensional porous MOF,

more preferably, the dibasic, tribasic or tetrabasic carboxylic acid organic ligand comprises at least one of the following:

more preferably, the sulfonic acid functionalized dicarboxylic acid organic ligand comprises at least one of the following:

in some embodiments, preferably, the method of surface modification comprises at least one of a surface coating method, a composite surface coating method, a surface deposition method, a surface in-situ growth coating method, and a hydrothermal method;

preferably, the surface coating method includes the steps of:

(01) Dispersing a functional material in a dispersing solvent to obtain a dispersion liquid;

(02) Transferring the dispersion liquid to the surface of the microporous membrane by at least one of dipping, coating or spraying to obtain a microporous membrane with a pretreated surface coating;

(03) And drying the microporous membrane with the surface coated with the pretreatment to obtain the surface modified microporous membrane.

Wherein, in the step (01), the dispersion solvent comprises at least one of fatty alcohol, alkane, ketone solvent, ester solvent and furan solvent, more preferably, the dispersion solvent comprises at least one of alkane and cycloalkane of C5-C8, fatty alcohol of C1-C7, acetone, butanone, ethyl acetate, propyl acetate, butyl acetate and tetrahydrofuran. The mass content of water in the dispersion solvent is not more than 70%.

In the embodiment of the invention, the polarity of the dispersion solution is preferably not more than methanol, the electric constant is less than or equal to 31.2, and the dipole moment is less than or equal to 6.2x10 ^-30 C.m, does not dissolve the high molecular material of the skeleton, and has lower toxicity and cost.

Preferably, the composite surface coating method comprises the following steps:

(11) Dispersing the functional material and the adhesive in a dispersing solvent to obtain dispersion liquid or gel;

(12) Transferring the dispersion or gel to the surface of the microporous membrane by at least one of dipping, coating or spraying to obtain a microporous membrane with a pretreated surface coating;

(13) And drying the microporous membrane with the pretreated surface coating to obtain the surface modified microporous membrane.

Wherein in the step (11), the dispersion solvent is capable of dispersing the binder as a solution, colloid, emulsion, suspension or gel; the mass content of water in the dispersion solvent is 10-70%;

the adhesive comprises at least one of a self-hydrophilic polymer material and the skeleton polymer material; preferably, the hydrophilic polymer material comprises at least one of polydopamine, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyethylene glycol, cellulose and chitosan; preferably at least one of polydopamine, polyvinyl alcohol, polyethylene glycol and chitosan. Wherein, when the binder uses hydrophilic polymer material, the microporous membrane is coated in the form of solution, colloid, emulsion or gel; when the binder uses the above-mentioned skeletal polymeric material, the microporous membrane is coated in the form of an emulsion.

In the step (13), when the mixture of the functional material and the binder is a gel or an emulsion, freeze-drying is preferably used as the drying method. A large number of pore structures can be formed in the freeze drying process, which is beneficial to subsequent application.

Preferably, the surface deposition method comprises the steps of:

(21) Dispersing a functional material in a dispersing solvent to obtain a dispersion liquid;

(22) Filtering the dispersion liquid under normal pressure/reduced pressure/positive pressure, and depositing a functional material on the surface of the microporous membrane;

(23) And drying the deposited microporous membrane to obtain the surface modified microporous membrane.

In the step (22), when the particle size of the functional material is smaller than the pore size of the microporous membrane, the functional material particles are loaded in the pores of the microporous membrane and/or the surface of the fibrous structure of the microporous membrane; when the particle size of the functional material is larger than the pore diameter of the microporous membrane, the functional material particles are loaded on the surface of the microporous membrane.

Preferably, the surface in-situ growth coating method comprises the following steps:

(31) Coating metal ion salt solution and organic ligand solution on the surface of the microporous membrane simultaneously or sequentially, so that the two solutions are partially or fully immersed into the microporous membrane to obtain a prefabricated microporous membrane;

(32) And drying the prefabricated microporous membrane to obtain the surface modified microporous membrane.

In the step (31), the metal ions and the organic ligands of the metal ion salt solution are identical to those of the above coordination polymer.

In the step (32), the drying temperature is 20 to 180 ℃.

Preferably, the hydrothermal method comprises the steps of:

(41) Placing the microporous membrane and the coordination polymer reaction solution into a corrosion-resistant reaction kettle, and growing and coating the coordination polymer on the surface of the microporous membrane in situ by a hydrothermal method to obtain a prefabricated microporous membrane;

(42) Washing the prefabricated microporous membrane to remove impurities, and drying to obtain the surface modified microporous membrane.

In the step (41), the temperature of the hydrothermal reaction is 90-200 ℃ and the reaction time is 1-48 h.

The surface modified microporous membrane provided by the embodiment of the invention has free radical quenching capability and certain oxidation resistance, and can be applied to the field of filtration and separation with special requirements; the composite ion exchange membrane has better hydrophilicity and higher surface energy, is more beneficial to the infiltration of ion exchange resin dispersion liquid and the filling of ion exchange resin, and is beneficial to the processing of the composite ion exchange membrane and the improvement of comprehensive performance.

In some embodiments, preferably, the surface modified microporous film includes 0.1 to 100 parts of a functional material and 100 parts of a backbone polymer material in parts by mass.

In some embodiments, it is preferred that the surface modified microporous membrane has an average pore size of 0.01 μm to 1 μm, preferably 0.03 μm to 0.7 μm, more preferably 0.05 μm to 0.5 μm; the porosity is 30% to 95%, preferably 40% to 90%, more preferably 45% to 90%, and even more preferably 50% to 90%.

In some embodiments, preferably, the surface modified microporous membrane is a hollow fiber membrane, a tubular membrane, or a commodity valve structure, preferably a flat sheet membrane structure. Further preferably, the thickness of the surface-modified micropores is 1 μm to 1mm, preferably 2 μm to 300 μm, more preferably 3 μm to 200 μm, still more preferably 3 μm to 150 μm.

In some embodiments, preferably, the functional material is distributed in the microporous membrane face and/or microporous membrane pores and/or microporous membrane structural surface. Preferably, the functional materials distributed on the microporous membrane surface can be distributed in discrete points, or can form a continuous functional material membrane layer. The thickness of the functional material film layer may be 1mm or more, and may be selected from 0.01 μm to 100. Mu.m, preferably 0.01 μm to 10. Mu.m, more preferably 0.01 μm to 5. Mu.m, and still more preferably 0.01 μm to 3. Mu.m. The functional material film layer can be distributed on one side or two sides of the microporous film.

The embodiment of the invention also provides a composite ion exchange membrane, which is characterized by comprising the surface modified microporous membrane.

In the composite ion exchange membrane provided by the embodiment of the invention, the content of the free radical quencher in the composite region of the microporous membrane and the ion exchange resin is controllable, so that the durability of the composite ion exchange membrane is enhanced; the microporous membrane improved by the hydrophilic functional material is beneficial to the infiltration of the ion exchange resin, improves the filling degree of the ion exchange resin in the microporous membrane, has better composite effect, ensures that the composite ion exchange membrane has better comprehensive performance and is convenient to apply in the related fields.

In some embodiments, preferably, the composite ion exchange membrane has a thickness of 3 to 500 μm, preferably 4 to 320 μm, more preferably 5 to 250 μm; the ion exchange capacity of the composite ion exchange membrane is 0.1 to 5.2mmol/g, preferably 0.15 to 4.0mmol/g, more preferably 0.2 to 2.5mmol/g.

In some embodiments, the surface modified microporous membrane of the composite ion exchange membrane preferably has a mass content of 0.1 to 90%, preferably 1 to 70%, more preferably 3 to 50%.

The preparation method of the composite ion exchange membrane can improve the binding force between the ion exchange resin and the filling modified microporous membrane, and the prepared composite ion exchange membrane has more stable performance; simple and easy to operate, high in production efficiency and convenient to popularize and apply in industrial production.

In some embodiments, in step (c), the drying temperature is 20 to 180 ℃.

In some embodiments, preferably, in the step (a), the molding solvent includes at least one of water, a high polarity organic solvent, tetrahydrofuran, and a fatty alcohol; wherein the high-polarity organic solvent comprises at least one of ethylene glycol, propylene glycol, glycerol, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoric triamide and N-methylpyrrolidone; the fatty alcohol includes at least one of methanol, ethanol, isopropanol, n-propanol, tert-butanol and n-butanol.

In some embodiments, preferably, in the step (a), the ion exchange resin comprises at least one of a perfluorosulfonic acid resin, a perfluorosulfonimide resin, a polyacid side chain type perfluororesin, a sulfonated polytrifluorostyrene, a sulfonated polysulfone, a sulfonated polyethersulfone, a sulfonated polyetheretherketone, a sulfonated polyaryletherketone, a sulfonated polyarylethernitrile, a sulfonated polyphosphazene, a sulfonated polyphenylene ether, a sulfonated polyphenylnitrile, a sulfonated polyimide, and a sulfonated polybenzimidazole; preferably comprises at least one of perfluorinated sulfonic acid resin, perfluorinated sulfonimide resin, polyacid side chain type perfluorinated resin, sulfonated polytrifluorostyrene, sulfonated polyether ether ketone, sulfonated polyaryletherketone and sulfonated polyarylethernitrile; more preferably at least one of perfluorosulfonic acid resin, perfluorosulfonimide resin, polyacid side chain type perfluororesin, and sulfonated polytrifluorostyrene.

Preferably, the perfluorosulfonic acid resin includes at least one of an acid type perfluorosulfonic acid resin, an alkali metal type perfluorosulfonic acid resin, and other cationic perfluorosulfonic acid resins; the structural general formula of the perfluorinated sulfonic acid resin is as follows:

wherein a=0 to 6, b=2 to 5, m "is hydrogen, lithium, sodium, potassium, rubidium, cesium or other cations, x mainly determines the ion exchange Equivalent (EW) of the perfluorosulfonic acid resin, and y mainly determines the molecular weight of the perfluorosulfonic acid resin;

The perfluorinated sulfonyl imide resin comprises at least one of acid type perfluorinated sulfonyl imide resin, alkali metal type perfluorinated sulfonyl imide resin and other cationic perfluorinated sulfonyl imide resin, and the structural general formula of the perfluorinated sulfonyl imide resin is as follows:

where a=0 to 6, b=2 to 5, c=0 to 5, m "is hydrogen, lithium, sodium, potassium, rubidium, cesium or other cations, x 'primarily determines the EW of the perfluorosulfonimide resin, and y' primarily determines the molecular weight of the perfluorosulfonimide resin.

The polyacid side-chain type perfluorinated resin comprises at least one of acid type polyacid side-chain type perfluorinated resin, alkali metal type polyacid side-chain type perfluorinated resin and other cationic type polyacid side-chain type perfluorinated resin, and the structural general formula of the polyacid side-chain type perfluorinated resin is as follows:

wherein a=0 to 6, b=2 to 5, c=0 to 5, m "is hydrogen, lithium, sodium, potassium, rubidium, cesium or other cations, x" mainly determines EW of the polyacid side chain type perfluorinated resin, and y "mainly determines molecular weight of the polyacid side chain type perfluorinated resin.

The sulfonated poly (trifluorostyrene) has a structural general formula:

wherein M' is hydrogen, lithium, sodium, potassium, rubidium, cesium or other cations, X ₁ Selected from H, F or CF ₃ X ' ", y '" and z ' "primarily determine the molecular weight and EW of the sulfonated polytrifluorostyrene.

The other cations include at least one of ammonium ion, alkaline earth metal ion, iron ion, vanadium ion, titanium ion, cobalt ion, chromium ion, nickel ion, copper ion, aluminum ion, silver ion, zinc ion, manganese ion, and tin ion.

The technical scheme of the present invention is described in detail below with reference to specific embodiments and drawings.

Cerium salt and organic ligand used in the embodiment of the invention are from chemical reagent suppliers such as Allatin, microphone reagent, piobtained pharmaceutical industry, music research reagent and the like; the perfluorosulfonic acid resin is derived from Kemu, 3M and Sorvy. Polyacid side chain type perfluorinated resins are derived from 3M; the high molecular materials of the framework are all commercial products; other solvents are common chemical agents. The nano-scale functionalized metal oxide is treated by a ball mill, and the particle size distribution of the particles is 10-40 nm.

The preparation method of the nanoscale functionalized metal oxide comprises the following steps:

the nano-scale sulfonated cerium oxide and the nano-scale sulfonated manganese dioxide are prepared by mixing nano-scale metal oxide with sulfonating agents such as fuming sulfuric acid, acetylsulfuric acid or chlorosulfonic acid and grafting sulfonic acid groups on the surface of a nano-material under anhydrous conditions; or dispersing the nanoscale metal oxide in sulfuric acid aqueous solution, and grafting sulfonic acid groups on the surface of the nanomaterial by ultrasonic assistance.

Specifically, 0.5g of nano cerium oxide is added into 15mL of 0.5M sulfuric acid solution, the ultrasonic action is carried out for 1h, and the solution is dried for 24h at 100 ℃ to obtain the final nano sulfonated cerium oxide powder. The same method can be used for preparing nano-grade sulfonated manganese dioxide powder.

The preparation of nano-scale phosphorylated cerium oxide and nano-scale phosphorylated manganese dioxide is to mix nano-scale metal oxide with orthophosphoric acid or phosphoric acid polymer to graft phosphoric acid group on the surface of nano-material, and urea and dicyandiamide can be added as catalysts.

Specifically, nano cerium oxide (0.6 g), dicyandiamide (1 g) and urea (1.5 g) were added to DMF (15 mL), and stirred at 135 ℃ to obtain a mixture; DMF (5 mL) and H were then slowly added ₃ PO ₄ 85% (2 g) of the mixture; after reacting for 1h, filtering to obtain nanoscale phosphorylated cerium oxide; repeatedly using water and ethanol for washing, and drying to obtain the clean nano-scale phosphorylated cerium oxide solid powder. The same method can be used for preparing nano-scale phosphorylated manganese dioxide powder.

The preparation method of the perfluorinated sulfonyl imide resin comprises the following steps: the perfluorinated sulfonyl imide resin is prepared by the free radical copolymerization of perfluorinated sulfonyl imide vinyl ether monomer and tetrafluoroethylene monomer.

Specifically, perfluorinated sulfonimide monomer and tetrafluoroethylene monomer (TFE) in Na ₂ HPO ₄ /NaH ₂ PO ₄ The buffer solution is prepared from (NH) ₄ ) ₂ S ₂ O ₈ /NaHSO ₃ As initiator, continuous copolymerization was carried out. First Na is added to ₂ HPO ₄ ·7H ₂ O and NaH ₂ PO ₄ Fully dissolving in de-aerated deionized water (a proper amount of surfactant can be added) to prepare a solution 1; subsequently, the sulfonimide monomer 1 was added to the solution 1, and the solution was cooled to 8℃with continuous nitrogen, and then the initiator was added to prepare a solution 2. Will be highThe autoclave was evacuated and after 3 purges with nitrogen in 5 minutes the initiator was added to solution 2; adding the solution 2 into a metering pump reservoir, and degassing with helium for more than 20 min; solution 2 was drawn into a fully evacuated autoclave and a suitable amount of de-aerated deionized water was added to make the solution half the volume of the reactor. When the reactor temperature reached 10 ℃, TFE was added to a pressure of 150psi and the continuous addition pump was started to maintain the pressure between 145 and 150psi throughout the process by adding TFE; and finally, acidifying the filtrate with 70% hydrochloric acid to obtain a precipitated polymer, washing the polymer with water until the polymer is neutral, and drying the polymer in full vacuum at 50 ℃ for more than 12 hours to obtain the perfluorinated sulfonyl imide resin.

Example 1

The metal salt and the organic ligand are fully mixed in a solvent, the coordination polymer with a one-dimensional, two-dimensional or three-dimensional structure is prepared by a hydrothermal method or room temperature volatilization, and the coordination polymer is processed into solid particles by a grinding and ball milling method. The metal salt, organic ligand and chemical structural formula used for preparing the coordination polymer are shown in table 1, the unit cell size, topological structure and solid particle size distribution are shown in table 2, wherein the unit cell volume is measured by adopting a single crystal X-ray diffraction method.

TABLE 1

TABLE 2

Example 2

Metal salt and organic ligand are fully mixed in a solvent, MOF with a two-dimensional porous structure or a three-dimensional porous structure is prepared by a hydrothermal method, and the MOF is processed into solid particles by a grinding and ball milling method. The metal salts, organic ligands, topology, BET specific surface area, micropore volume and solid particle size distribution used for MOF preparation are shown in table 3, wherein,

particle size distribution of MOF: determination using SEM observation;

BET specific surface area of MOF: measuring by using ASIQ-MI001-5 physical adsorption instrument of Kang Da company in the United states;

micropore volume of MOF: calculated by the t-plot method.

TABLE 3 Table 3

Example 3

CPs-1 of example 1 was dispersed in ethanol to form a suspension having a concentration of 2mg/mL, and coated on both sides of a polytetrafluoroethylene microporous membrane (e-PTFE-1, porosity: 74%) by doctor blade, and dried at 100℃for 5 minutes to obtain a surface-modified microporous membrane MF-1. The functional material in MF-1 is mainly loaded in pores formed by PTFE fiber structure and on the surface of the fiber structure, and a small amount of functional material is discretely distributed on the membrane surface.

Example 4

CPs-3 of example 1 was dispersed in cyclohexane to form an emulsion having a concentration of 20mg/mL, and coated on both sides of e-PTFE-1 by doctor blade, and dried at 100deg.C for 5min to obtain a surface-modified microporous membrane MF-2. The distribution of the functional material is the same as MF-1.

Example 5

CPs-5 of example 1 was dispersed in water to isopropanol (water to alcohol mass ratio of 2:3) to form a 50mg/mL solution. E-PTFE-1 is immersed in the solution and dried for 5min at 100 ℃ to obtain the surface modified microporous membrane MF-3. The distribution of the functional material is the same as MF-1.

Example 6

Unlike example 5, when the microporous membrane skeleton polymer material is polyaryletherketone, polysulfone, polyethersulfone ketone, polyaramid, polyimide, the surface modified microporous membranes MF-4, MF-5, MF-6, MF-7 and MF-8 are produced. Except polyimide, other microporous membranes are prepared by a heat value phase separation and/or dissolution method, and do not contain fiber structures, wherein functional materials are mainly loaded in pores and pore surfaces of skeleton high polymer materials in MF-4, MF-5, MF-6 and MF-7, and a small amount of functional materials are discretely distributed on the membrane surface. MF-8 is consistent with the functional material loading of MF-1.

Example 7

Unlike example 3, the supported functional material was a mixture of equal mass of MOF-1, MOF-2 and nano-sized sulfonated manganese dioxide to produce a surface modified microporous membrane MF-9.

Example 8

Unlike example 5, the supported functional materials were CPs-5, phosphorylated manganese dioxide, sulfonated ceria and phosphorylated ceria of equal mass to produce a surface modified microporous membrane MF-10.

Example 9

The CPs-2 of example 1 were supported on ETFE microporous membrane (porosity 71%) by surface in-situ growth coating method. Molar ratio of 1:3 (CeNO ₃ ) ₃ ·6H ₂ Adding O and pivalic acid into methanol solvent, adding triethylamine, stirring thoroughly to dissolve, and filtering. The filtrate is coated on two sides of the ETFE microporous membrane, and slowly volatilizes at room temperature to grow and coat CPs-2 on the surface of the microporous membrane, so as to obtain the surface modified microporous membrane MF-11. The distribution of the functional material is the same as MF-1.

Example 10

CPs-4 of example 1 was supported on a polytetrafluoroethylene microporous membrane (e-PTFE-2, 85% porosity) by a surface in-situ growth coating method. CeCl with a molar ratio of 1:3 ₃ ·7H ₂ O and [ 5-ethoxycarbonyl-6- (4-bromophenyl) -1, 6-dihydropyrimidinone]Methanesulfonic acid (HL 1) is put into a beaker, then mixed solvent of water and ethanol (the mass ratio of water to ethanol is 1:1) is added, stirring is carried out, dissolution is carried out, and the solution is filtered to obtain filtrate. And (3) dipping the e-PTFE-2 into the filtrate, taking out, slowly volatilizing at room temperature, and growing and coating CPs-4 on the surface of the microporous membrane to obtain the surface modified microporous membrane MF-12. The distribution of the functional material is the same as MF-1.

Example 11

Unlike example 10, the CPs-4 surface modified microporous membrane was a polyethersulfone microporous membrane (55% porosity), resulting in a surface modified microporous membrane MF-13. The distribution of the functional material is the same as that of MF-4.

Example 12

And (3) coating and supporting the surface of the CPs-5 on the surface of the e-PTFE-1 by in-situ growth through a hydrothermal method. The tridentate aromatic carboxylic acid ligand N- (4-benzoic acid group) iminodiacetic acid (H) with the molar ratio of 1:1 ₂ L2) and (CeNO) ₃ ) ₃ ·6H ₂ O was added to a mixed solution of acetonitrile and water in a volume ratio of 1:1, stirred at room temperature for 20min, and ph=2 of the system was adjusted with 1M HCl solution. e-PTFE-1 is immersed in the solution, reacted for 3 days at 120 ℃ in a hydrothermal kettle, and cooled to room temperature at a rate of 5 ℃ per hour reduction, thus obtaining the surface modified microporous membrane MF-14. The distribution of the functional material is the same as MF-1.

Example 13

The microporous membrane is surface modified by a mixture of polymer and functional material. CPs-6, MOF-3, polydopamine and polyvinyl alcohol with equal mass are dissolved and dispersed in a mixed solvent of water and n-propanol (the mass ratio of water to alcohol is 1:2) to obtain a solution with the concentration of 50 mg/mL. Coating the solution on two sides of the e-PTFE-1, and drying at 60 ℃ for 15min to obtain the surface modified microporous membrane MF-15. The functional material is loaded in pores formed by the PTFE fiber structure and the surface of the fiber structure through a polymer adhesive, and a small amount of functional material is discretely distributed on the membrane surface.

Example 14

Equal mass CPs-7, MOF-4, polyethylene glycol and chitosan are dissolved and dispersed in a mixed solvent of water and tertiary butanol (the mass ratio of water to alcohol is 3:7) to obtain a gel-like mixture with the concentration of 500 mg/mL. The mixture is coated on two sides of the e-PTFE-1, and the surface modified microporous membrane MF-16 is obtained after freeze drying. The functional material and the adhesive are partially loaded in pores formed by the PTFE fiber structure and the surface of the fiber structure, and a composite functional layer with the thickness of 0.5-3 mu m is formed on the film surface.

Example 15

Equal mass of MOF-5, MOF-6, MOF-7, sulfonated ceria and polytetrafluoroethylene were mixed with other substances as an adhesive in the form of an emulsion, and the solid content of the polytetrafluoroethylene emulsion was 50%. The mixture was dispersed in a mixed solvent of water and isooctanol (water to alcohol mass ratio 5:5) to give an emulsion having a concentration of 50 mg/mL. The mixture is coated on two sides of the e-PTFE-1, and the surface modified microporous membrane MF-17 is obtained after freeze drying. The functional material and the adhesive are partially loaded in pores formed by the PTFE fiber structure and on the surface of the fiber structure, and a composite functional layer with the thickness of 0.1-0.5 mu m is formed on the film surface.

Example 16

Unlike example 15, the backbone polymer materials of the microporous membranes were polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene/PEO polymer alloy, PEP, PVF, PFA and ECTFE, resulting in surface modified microporous membranes MF-18, MF-19, MF-20, MF-21, MF-22, MF-23, MF-24 and MF-25. In the embodiment, the porosity of the polypropylene microporous membrane is 50%, the porosity of the PEP microporous membrane is 80%, and the functional material loading conditions of all the surface microporous membranes are the same as those of MF-17.

Example 17

The MOF-8 of example 1 was treated with a ball mill to make the particle size of the solid particles 20 to 50nm, and then a surface-modified microporous membrane was produced by a surface deposition method. Equal mass CPs-7, MOF-8 and sulfonated cerium oxide are dispersed in a mixed solvent of water and ethanol (the mass ratio of water to ethanol is 1:1) to obtain a mixture dispersion liquid. PVDF microporous membrane and e-PTFE-1 are used as filter membranes, and the dispersion liquid is subjected to vacuum filtration. And drying the filtered filter membrane by blowing to obtain the surface modified microporous membranes MF-26 and MF-27. The functional material particle size is smaller than the pore size of most pores of the microporous membrane, and the loading condition of the functional materials MF-26 and MF-27 is the same as that of MF-1.

Example 18

MOF-8 of example 1 was dispersed in water to obtain a dispersion. PVDF microporous membrane (porosity is 92%), ETFE microporous membrane and e-PTFE-1 are used as filter membranes, and the dispersion liquid is subjected to vacuum filtration. And drying the filtered filter membrane by blowing to obtain the surface modified microporous membranes MF-28, MF-29 and MF-30. Because the particle size of the functional material particles is larger, the functional material is partially loaded in the pores formed by the fiber structure and on the surface of the fiber structure, and the functional material layer with the thickness of 0.3-1.5 mu m is formed on the film surface.

Example 19

The D520 resin dispersion (KUK, mass content of perfluorosulfonic acid resin: 5%, EW: 980g/mol, solvent: water, mixed solvent of ethanol and n-propanol) was knife-coated on both sides of the surface-modified microporous membranes MF-1, MF-11, MF-17, MF-19, MF-22 and MF-26, dried at 80℃for 15min, and heat-treated at 150℃for 15min to prepare composite ion exchange membranes PEM-1, PEM-2, PEM-3, PEM-4, PEM-5 and PEM-6. The chemical structure of the perfluorosulfonic acid resin in the D520 resin dispersion liquid is as follows:

Example 20

A perfluorosulfonimide resin (PFSN) was dissolved and dispersed in a mixed solvent of DMAc and isopropyl alcohol (mass ratio of DMAc to isopropyl alcohol: 2:8) to obtain a resin dispersion having a solid content of 20%. The resin dispersion was slit coated on both sides of MF-12 and MF-13 and dried to produce composite ion exchange membranes PEM-7 and PEM-8. The perfluorinated sulfimide resin is self-made and is obtained by copolymerizing tetrafluoroethylene and sulfimide monomers, the EW value is 1200g/mol, and the structural formula is as follows:

example 21

The ion exchange resin was dissolved and dispersed in a mixed solvent of water and n-propanol (water-alcohol mass ratio: 1:2) to obtain a resin dispersion having a solid content of 15%. The resin dispersion was slit coated on both sides of MF-17 and dried to produce composite ion exchange membranes PEM-9, PEM-10, PEM-11 and PEM-12. The ion exchange resins used in this example were BAM3G, D, 3M800 and PFIA.

BAM3G is from Barad, sulfonated poly (trifluorostyrene) resin, EW value is 407G/mol, and structural formula is:

wherein X is ₁ Is F or CF ₃ The ratio of the 2 substituents is not defined.

D72 is from Sorve, perfluorinated sulfonic acid resin, EW value is 720g/mol, and the structural formula is:

3M800 is from 3M company, perfluorosulfonic acid resin, EW value is 800g/mol, structural formula is:

PFIA is from 3M company, polyacid side chain type perfluorinated resin, EW value is 625g/mol, and structural formula is:

comparative example 1

Unlike example 19, the reinforcement materials were microporous films ePTFE-1 and ETFE microporous films that did not contain a functional material. Composite ion exchange membranes D-PEM-1 and D-PEM-2 were produced.

Comparative example 2

Unlike example 20, the reinforcement materials were microporous films e-PTFE-2 and polyethersulfone microporous films without functional materials. Composite ion exchange membranes D-PEM-3 and D-PEM-4 were produced.

Comparative example 3

Unlike example 21, the reinforcement material was microporous membrane e-PTFE-1 without functional material, and the ion exchange resins were PFIA and BAM3G. Composite ion exchange membranes D-PEM-5 and D-PEM-6 were produced.

Test examples

The test method of the correlation performance is as follows:

the method for testing the aperture of the microporous membrane adopts a bubble pressure method (gas-liquid displacement driving technology), the testing instrument adopts a Porometer3G aperture analyzer, and a wet-first-dry-then-dry mode is adopted, namely, the microporous membrane is filled with liquid capable of being infiltrated with the microporous membraneAnd wetting, then applying pressure difference to two sides of the membrane, overcoming the surface tension of the impregnating solution in the pore canal of the membrane, and driving the impregnating solution to pass through the pore canal so as to obtain the pore diameter distribution of the microporous membrane. The air source is compressed air and nitrogen, and the test area is 3.14cm ² . 3 to 5 groups of samples were taken each time for parallel experiments.

The microporous membrane porosity test equipment is a high-precision Tianping and true density analyzer with the concentration of 0.01 g; as test samples, 3 square films of the same specification and size were cut without wrinkles, defects and breakage. The mass of 3 samples was weighed using an analytical balance. Bulk density was calculated as apparent density of the sample according to the following formula (1):

wherein:

ρ -bulk density of sample in grams per cubic centimeter (g/cm) ³ )；

m-mass measurement of the sample in grams (g);

d-thickness measurement of the sample in micrometers (μm);

s-sample area, fixed as the sampling knife area, of 25cm ² ；

The porosity was calculated according to the following formula (2):

wherein:

p—porosity of sample, dimensionless physical quantity (%);

apparent density of ρ -sample, measured in grams per cubic centimeter (g/cm) ³ )；

ρ ₀ The true density of the test specimens in grams per cubic centimeter (g/cm) ³ ) And the sample is obtained by testing by a true density analyzer.

The contact angle test adopts a sitting drop method, the liquid drop is water, and the solid sample is a microporous membrane. The smaller the contact angle, the better the hydrophilicity, the smaller the contact angle of the droplet with the microporous membrane at 16 seconds of measurement.

The measuring equipment of the thickness of the microporous membrane is a contact flat-head thickness gauge, three microporous membranes cut by a cutter are used as test samples, matrix tests are carried out along the equidistant sampling points in the MD (longitudinal) and TD (transverse) directions of the samples during thickness measurement, and the average value of each point is calculated to be the average thickness of the membrane.

Resistance to free radicals: the ion exchange membrane was immersed in Fenton (Fenton) reagent at 80℃for 8 hours, comparing the mass loss before and after treatment with different immersion times. Preparation of Fenton reagent: to 50mL of H with mass fraction of 3% ₂ O ₂ 0.1mL of Fe with the mass concentration of 0.01mol/L is added dropwise into the solution ²⁺ The solution is prepared into the Fenton reagent which is prepared and used at present. The smaller the percentage of mass loss, the better the radical resistance.

Oxidation resistance: and evaluating the oxidation resistance of the ion exchange membrane when the ion exchange membrane is applied to a flow battery diaphragm by adopting a pentavalent vanadium ion oxidation method. The specific test method comprises the following steps: soaking ion exchange membrane in 1.7mol/L pentavalent vanadium ion solution and 3mol/L H ₂ SO ₄ In the aqueous solution, soaking is carried out for 100 hours, the soaking state of the diaphragm and the change of the residual mass are observed, and the larger the ratio of the residual mass to the initial mass before soaking is, the better the oxidation resistance is, and the representation is expressed by the percentage of the residual mass to the initial mass.

The method for testing the conductivity, EW, IEC and tensile strength is described in section 3 of proton exchange membrane fuel cell with reference to GB/T20042.3-2022: proton exchange membrane test methods. Wherein the conductivity is measured at 80℃and 30% relative humidity.

The test method of the power density curve of the fuel cell is referred to GB/T20042.5-2022 proton exchange membrane fuel cell part 5: membrane electrode test method, test conditions are 80 ℃ and relative humidity is 95%.

The test method of the performance of the flow battery is referred to NB/T42081-2016, all-vanadium flow battery single cell performance test method.

(1) Contact angle tests were performed on MF-1, MF-2, MF-12, MF-17, MF-27, and e-PTFE-1, and the results are shown in FIG. 1:

as can be seen from fig. 1, the surface modified microporous membrane prepared using different functional materials and different methods has better hydrophilicity than e-PTFE-1, facilitating its application as a reinforcing layer in a composite ion exchange membrane.

(2) The total mass and porosity of the skeleton polymer material, the loaded functional material, the functional material and the adhesive of the surface modified microporous membrane are shown in Table 4.

TABLE 4 Table 4

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As can be seen from the data in table 4, the surface modified microporous membrane is obtained by loading the functional material on the surface of the microporous membrane in different ways, and all the surface microporous membranes are loaded with the functional material, can maintain proper porosity, and has the basic characteristics of the microporous membrane.

(3) Table 5 shows the thickness, average pore size and pore size distribution of the surface-modified microporous membrane

TABLE 5

As can be seen from the data in table 5, the functional material is supported on the surface and inside of the microporous membrane after surface modification, so that the thickness of the microporous membrane is slightly increased, the average pore diameter is reduced, and the pore size distribution range is narrowed, as compared with the unmodified original microporous membrane.

As a result of testing the crystallization behavior of the MF-1 and e-PTFE-1, as shown in FIG. 2, the MF-1 had a hydrophilic CPs-1 loaded, so that the evaporation peak of water appeared near 100deg.C, and after 300 deg.C, the decomposition peak of CPs-1 overlapped with the crystallization melting peak of PTFE, resulting in a fluctuating, sharp DSC temperature rise curve. The e-PTFE-1 only contains a skeleton polymer material PTFE, and does not contain other substances, the DSC curve of the skeleton polymer material PTFE before 280 ℃ is quite gentle, and 2 crystallization melting peaks of the e-PTFE-1 appear after 300 ℃. DSC curves also demonstrate that the functional material is successfully loaded in the microporous membrane, and that the functional material has good thermal stability to meet the requirements for preparing the composite ion exchange membrane.

SEM scanning of MF-12 and e-PTFE-1 obtained in example 10 shows that in FIG. 3, dark-colored lump-like substances, which are a composite of a binder and a functional material, appear to adhere to the surface of a microporous membrane in the SEM image of MF-12.

(4) Table 6 is the thickness, IEC, radical resistance and oxidation resistance of the composite ion exchange membrane.

TABLE 6

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As can be seen from the data in table 6, the surface modified microporous membranes prepared by different skeleton polymer materials and modification methods can be composited with ion exchange resins to prepare composite ion exchange membranes. Compared with an unmodified microporous membrane, the surface modified microporous membrane of the same skeleton polymer material adopts the same ion exchange resin and the same process to prepare the composite ion exchange membrane, and the composite ion exchange membrane prepared by the surface modified microporous membrane has better free radical resistance and oxidation resistance and lower quality loss in the corresponding stability test.

(5) Table 7 shows the mechanical and electrochemical properties of the composite ion-exchange membrane

TABLE 7

	Ion exchange membrane	Tensile Strength (MPa)	Elongation at break (%)	Conductivity (S cm)
					Example 19	PEM-2	57.3	173	0.187
Example 21	PEM-12	51.3	135	0.230
					Comparative example 1	D-PEM-2	49.1	166	0.152
Comparative example 5	D-PEM-5	43.7	119	0.201

As can be seen from the data in Table 7, the composite ion exchange membrane with the surface modified microporous membrane as the reinforcing layer has better mechanical and electrochemical properties than the D-PEM-2. This is because the better hydrophilicity of the surface modified microporous membrane is favorable for the more sufficient filling of the ion exchange resin, the better compounding effect is achieved, and the mechanical property and the electrochemical property of the compound ion exchange membrane can be effectively improved. The same effect is also achieved with PEM-12 and D-PEM-5.

FIG. 4 is a graph of power density for PEM-2 and D-PEM-2, and it can be seen that PEM-2 has better cell performance.

Applying PEM-12 and D-PEM-5 to an all-vanadium redox flow battery, the energy efficiency of PEM-12 is 87.3% and the coulombic efficiency is 99.5%; the energy efficiency of D-PEM-5 was 81.9% and the coulombic efficiency was 97.4%. PEM-12, with the reinforcing layer being a surface modified microporous membrane, exhibits better cell performance as a flow battery separator.

For purposes of this disclosure, the terms "one embodiment," "some embodiments," "example," "a particular example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While the above embodiments have been shown and described, it should be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives, and variations of the above embodiments may be made by those of ordinary skill in the art without departing from the scope of the invention.

Claims

1. A method for preparing a surface modified microporous membrane, comprising the steps of:

(1) Preparing a skeleton polymer material into a microporous membrane;

2. The method of producing a surface-modified microporous film according to claim 1, wherein in the step (1), the skeletal polymeric material comprises at least one of polyolefin and aromatic polymer, preferably the skeletal polymeric material is polyolefin, preferably at least one of fluorinated polyolefin and non-fluorinated polyolefin;

The structural formula of the fluorine-containing olefin monomer is as follows:wherein R is ₆ Selected from F or C1-C6 perfluoroalkyl, preferably F, CF ₃ 、C ₂ F ₅ Or C ₃ F ₇ More preferably F or CF ₃ ；R ₇ 、R ₈ And R is ₉ A perfluoroalkyl group selected from H, F, cl, br, I or C1 to C6, preferably H, F, cl, br, I, more preferably H, F or Cl; further preferably, the fluoroolefin monomer comprises at least one of hexafluoropropylene, tetrafluoroethylene, trifluoroethylene, 1-difluoroethylene, 1, 2-difluoroethylene, vinyl fluoride, chlorotrifluoroethylene, 1-chloro-1, 2-difluoroethylene, 1-chloro-2-fluoroethylene, 1-chloro-1-fluoroethylene, 1-dichloro-2, 2-difluoroethylene, 1, 2-dichloro-1, 2-difluoroethylene, 1-dichloro-2-fluoroethylene, 1, 2-dichloro-fluoroethylene or trichlorofluoroethylene; preferably comprises hexafluoropropylene, tetrafluoroethylene, and tricycloVinyl fluoride, 1-difluoroethylene, 1, 2-difluoroethylene, vinyl fluoride, chlorotrifluoroethylene, preferably at least one of hexafluoropropylene, tetrafluoroethylene, trifluoroethylene, 1-difluoroethylene, 1, 2-difluoroethylene, vinyl fluoride, 1-chloro-1, 2-difluoroethylene, 1-chloro-2-fluoroethylene, 1-chloro-1-fluoroethylene or chlorotrifluoroethylene, more preferably at least one of hexafluoropropylene, tetrafluoroethylene, trifluoroethylene, 1-difluoroethylene, vinyl fluoride or chlorotrifluoroethylene;

3. The method of producing a surface-modified microporous film according to claim 2, wherein the fluorine-containing polyolefin comprises at least one of polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-propylene copolymer, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene-ethylene copolymer, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, polyvinyl fluoride, chlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer;

4. The method of making a surface modified microporous film of claim 1, wherein the functionalized metal oxide comprises at least one of a functionalized metal oxide of a lanthanide metal, iron, aluminum, manganese, zirconium; preferably, at least one of functionalized metal cerium oxide and functionalized metal manganese oxide is included; more preferably, at least one of phosphorylated ceria, sulfonated ceria, phosphorylated manganese dioxide and sulfonated manganese dioxide is included.

5. The method of preparing a surface modified microporous film according to claim 1 or 4, wherein the functionalized metal oxide is a nano-sized functionalized metal oxide, preferably having a particle size of less than 100nm, preferably less than 80nm.

6. The method of preparing a surface modified microporous film according to claim 1, wherein the metal ion of the coordination polymer ligand center comprises at least one of lanthanide metal ion, zirconium ion, iron ion, aluminum ion, manganese ion and zinc ion, preferably the metal ion comprises at least one of zirconium ion, manganese ion and cerium ion, preferably Ce ³⁺ 、Ce ⁴⁺ 、Mn ²⁺ 、Mn ³⁺ 、Mn ⁴⁺ At least one of them.

7. The method of producing a surface-modified microporous film according to claim 1 or 6, wherein the coordination polymer comprises at least one of a coordination polymer of one-dimensional structure, a coordination network of two-dimensional structure, and a coordination network of three-dimensional structure;

8. The method of producing a surface-modified microporous film according to claim 7, wherein the unit cell volume of the one-dimensional structured coordination polymer, the two-dimensional structured coordination network, and the three-dimensional structured coordination network isPreferential +.>More preferably +.>

9. The method of preparing a surface modified microporous membrane of claim 1 or 6, wherein the coordination polymer comprises at least one of a two-dimensional porous MOF and a three-dimensional porous MOF,

10. The method of claim 7, wherein in the step (2), the surface modification method comprises at least one of a surface coating method, a composite surface coating method, a surface deposition method, a surface in-situ growth coating method, and a hydrothermal method.

11. A surface modified microporous membrane produced by the method of any one of claims 1 to 10.

12. Use of the surface modified microporous film of claim 11 in filtration materials, sealing materials, textile materials, battery separators.

13. A composite ion exchange membrane comprising the surface modified microporous membrane of claim 11.

14. The method for preparing a composite ion exchange membrane according to claim 13, comprising the steps of:

15. Use of the composite ion exchange membrane of claim 13 in a fuel cell ion exchange membrane, an ion exchange membrane for hydrogen production from electrolyzed water, a flow battery membrane, a chlor-alkali industrial membrane, an electrodialysis membrane, or a permeation membrane.