CN115449107A

CN115449107A - Flexible alkaline polyelectrolyte membrane with three-dimensional network structure and preparation method thereof

Info

Publication number: CN115449107A
Application number: CN202211247263.3A
Authority: CN
Inventors: 徐铜文; 葛晓琳; 张华清
Original assignee: University of Science and Technology of China USTC
Current assignee: University of Science and Technology of China USTC
Priority date: 2022-10-12
Filing date: 2022-10-12
Publication date: 2022-12-09

Abstract

The invention provides a flexible three-dimensional network structure alkaline polyelectrolyte membrane, which is obtained by ion exchange after an anion functionalized polymer is formed into a membrane. The alkaline polyelectrolyte membrane with the flexible three-dimensional network structure simultaneously has the micropore characteristic of a rigid material and the excellent processability of a flexible material. The spirobifluorene unit with a non-coplanar twisted structure in the polymer serves as a rigid network node to force the molecular chain segments to extend towards different directions, so that a loose network structure is formed, and a large amount of free volume and micropores are formed. The three-dimensional network polymer prepared by the method has certain flexibility and elasticity, can be fully swelled in a solvent to form uniform colloid, is convenient for modification and functionalization reaction, and has excellent processability. The invention also provides a preparation method of the flexible three-dimensional network structure alkaline polyelectrolyte membrane.

Description

Flexible alkaline polyelectrolyte membrane with three-dimensional network structure and preparation method thereof

Technical Field

The invention belongs to the technical field of ion exchange membranes, and particularly relates to a flexible three-dimensional network structure alkaline polyelectrolyte membrane and a preparation method thereof.

Background

With the development of human society and the excessive exploitation and use of fossil energy, the problems of energy shortage, environmental pollution and the like become more serious. Therefore, the development and application of green clean energy and environmental treatment technologies are receiving much attention, such as flow batteries, fuel cells, hydrogen production by water electrolysis, electrodialysis, electrochemical synthesis of ammonia, and the like.

The basic polyelectrolyte membrane has great application requirements in the fields, and the ion conductivity, selectivity, chemical stability and other properties of the basic polyelectrolyte membrane directly influence the service efficiency and the service life of an application device. For a long time, the traditional ion transmission channel is constructed based on the formation of a thermodynamically driven hydrophilic and hydrophobic microphase separation structure, which is generally weak in function and difficult to control, thereby making it difficult to balance conductivity and selectivity. The polymer can form a microstructure with special molecular configuration and micropores by regulating the conformation of the molecular chain segment of the polymer so as to influence the movement and the stacking behavior of the polymer, thereby more efficiently constructing an ion transmission channel in a membrane and endowing the material with excellent ion conduction capability and selectivity. In addition, the material should be designed with sufficient consideration of chemical stability and processability to facilitate subsequent functionalization and material processing. For example, the self-polymerization microporous polymer molecular chain with the double-bond bridge structure has low internal rotation freedom degree, the tight accumulation among the molecular chains is inhibited, a larger free volume is formed to be used as a high-efficiency ion conduction channel, but the chemical stability of the self-polymerization microporous polymer molecular chain is insufficient due to heteroatoms contained in the double-bond bridge structure. Other hypercrosslinked or conjugated microporous polymers generally have the problems of poor solubility and processability, difficult functionalization and the like.

Disclosure of Invention

The alkaline polyelectrolyte membrane has the micropore characteristic of a rigid network structure and the easy processability of a flexible material, and has excellent ionic conductivity, selectivity and chemical stability.

The invention provides a flexible three-dimensional network structure alkaline polyelectrolyte membrane, which is obtained by performing ion exchange after forming a membrane of an anionic functional polymer;

the anion functionalized polymer has a structure shown in formula I or formula II:

n1 is an integer between 10000 and 8000, n2 is an integer between 10000 and 8000, x is an integer between 10000 and 8000, y is an integer between 10000 and 8000, x is less than or equal to n1/2, y is less than or equal to n2/2;

wherein Ar is selected from a structure shown in formula 1 and/or formula 2, and m is an integer of 0-3;

r is selected from one of the formulas 3 to 7, and R is an integer of 1 to 10;

q is selected from one of quaternary ammonium salt, quaternary phosphine salt, imidazole salt, piperidine salt cation and derivatives thereof.

The invention provides a preparation method of the flexible three-dimensional network structure alkaline polyelectrolyte membrane, which comprises the following steps:

a) Carrying out condensation polymerization on spirobifluorene, aryl monomers and ketone monomers under the action of a first solvent and a catalyst through a Friedel-crafts reaction to obtain a polymer with a network structure;

b) Swelling the network structure polymer in a second solvent, heating and stirring to form uniform colloid, and then adding the cation functionalized micromolecule and an acid-binding agent into the colloid for reaction to obtain a functionalized polymer;

c) And mixing the functional polymer and a third solvent, heating and stirring to form uniform colloid, coating the colloid to form a film, and then carrying out ion exchange on the obtained film layer in an anion exchange solution to obtain the anion-associated alkaline polyelectrolyte film.

Preferably, in the step A), the aryl monomer is one or more of biphenyl, p-terphenyl and m-terphenyl;

the ketone monomer is one or more of N-methyl-4-piperidone, 2-trifluoro acetophenone, indolone, 1-trifluoroacetone and derivatives thereof;

the first solvent is one or more of dichloromethane, trichloromethane and 1, 2-dichloroethane;

the catalyst is trifluoroacetic acid and/or trifluoromethanesulfonic acid.

Preferably, the mole ratio of the spirobifluorene to the aryl monomer is (0.1-1): 1; the molar ratio of the aryl monomer to the ketone monomer is 1: (1-1.5); the volume ratio of the first solvent to the catalyst is (0-2): 1, and the ratio of the total molar amount of the spirobifluorene, the aryl monomer and the ketone monomer to the volume of the first solvent is (0.3-1) mol:100mL.

Preferably, the polycondensation temperature is-5-30 ℃, and the polycondensation time is 0.5-48 hours.

Preferably, the second solvent is one or more of N, N-dimethylformamide, N-diethylformamide, dimethyl sulfoxide and N-methylpyrrolidone;

the cationic functional micromolecules are one or more of methyl iodide, trimethylamine, N-methylimidazole and N-methylpiperidine;

the acid-binding agent is one or more of anhydrous potassium carbonate, triethylamine, pyridine and diisopropylethylamine.

Preferably, the ratio of the mass of the network structure polymer to the volume of the second solvent is (2 to 5) g:100mL; the molar ratio of the network structure polymer to the cationic functionalized micromolecules is (0.5-2): 1; the molar ratio of the acid-binding agent to the cationic functionalized micromolecules is (1-4): 1.

preferably, the temperature of the reaction in the step B) is 25-120 ℃; the reaction time in the step B) is 1 to 3 days.

Preferably, the third solvent is one or more of N, N-dimethylformamide, N-diethylformamide, dimethyl sulfoxide and N-methylpyrrolidone;

the anion exchange solution comprises NaOH, KOH, naCl, KCl, naBr, KBr and NaSO ₄ And NaCO ₃ One or more of the above; the concentration of the anion exchange solution is 0.5-5 mol/L.

Preferably, the ion exchange is carried out under the condition of air isolation, the time of the ion exchange is 12 to 36 hours, and the anion exchange solution is replaced every 1 to 3 hours.

The invention provides a flexible three-dimensional network structure alkaline polyelectrolyte membrane, which is obtained by forming a membrane from an anionic functional polymer and then carrying out ion exchange; the anion functionalized polymer has a structure shown in a formula I or a formula II. The invention designs a basic polyelectrolyte membrane with a flexible three-dimensional network structure, and the material has the micropore characteristic of a rigid material and the excellent processability of a flexible material. The spirobifluorene unit with a non-coplanar twisted structure in the polymer serves as a rigid network node to force the molecular chain segments to extend towards different directions, so that a loose network structure is formed, and a large amount of free volume and micropores are formed. The free volume and the micropores can be used as high-efficiency channels for ion selective transmission, so that the prepared alkaline polyelectrolyte membrane has very excellent ion conduction capability and OH at 80 DEG C ^- The ionic conductivity can reach 150mS/cm, cl ^- SO ₄ ^2- The conductivity of the anion with equal volume can reach 100mS/cm, which is more than one time higher than that of the commercial alkaline membrane AMV on the market. On the other hand, the polymer with over-strong rigidity or network structure usually faces the problem that the polymer can not be dissolved so as to be difficult to carry out subsequent functionalization and processing to form a film, but the rest parts of the main chain of the polymer prepared by the invention are connected by the aromatic hydrocarbon and the flexible methylene which can rotate, so that the formed three-dimensional network polymer has certain flexibility and elasticity, can be fully swelled in a solvent to form uniform colloid, is convenient for carrying out modification and functionalization reactions, has excellent processability, and overcomes the obstruction of the polymer with similar structure to the subsequent reaction and processing due to poor solubility. The prepared alkaline polyelectrolyte membrane has excellent mechanical strength inThe tensile strength at room temperature is higher than 20MPa. In addition, the main chain with an all-carbon structure synthesized by the super-strong acid catalytic reaction avoids sensitive polar groups such as aryl ether bonds and the like, so that the prepared alkaline polyelectrolyte membrane has excellent chemical stability, and the ion exchange capacity and the conductivity retention rate of the membrane are maintained to be more than 90% after the membrane is soaked in a 1mol/L NaOH solution at the temperature of 80 ℃ for a long time.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic structural view of an anion functionalized polymer of the present invention;

FIG. 2 is a mechanical property test of the alkaline polyelectrolyte membrane obtained in example 1 of the present invention;

FIG. 3 is a temperature-rise conductivity test of the basic polyelectrolyte membrane obtained in example 1 of the invention;

FIG. 4 is a chemical stability test of the basic polyelectrolyte membrane obtained in example 1 of the invention.

Detailed Description

The invention provides a flexible three-dimensional network structure alkaline polyelectrolyte membrane, which is obtained by forming a membrane from an anionic functional polymer and then carrying out ion exchange;

n1 is an integer between 10000 and 8000, n2 is an integer between 10000 and 8000, x is an integer between 10000 and 8000, y is an integer between 10000 and 8000, x is less than or equal to n1/2, y is less than or equal to n2/2; wherein Ar is selected from a structure shown in formula 1 and/or formula 2, m is an integer of 0-3, such as 0,1,2,3;

r is selected from one of formulas 3 to 7, R is an integer of 1 to 10, such as 1,2,3,4,5,6,7,8,9, 10;

formula 7;

q is selected from quaternary ammonium salt, quaternary phosphine salt, imidazole salt, piperidine salt cation and derivatives thereof, more preferably, Q can be any one of formulas 8-10,

as shown in a structural schematic diagram 1 of the anion functionalized polymer, spirobifluorene with a rigid twisted structure is used as a network node, so that two molecular chain segments containing flexible methylene groups extend towards two non-coplanar directions, a unique flexible three-dimensional network structure is formed, a loose and porous structure is further formed, efficient transmission of ions is promoted, and meanwhile, the flexible groups contained in the chain segments endow the material with good processability and mechanical properties.

The invention also provides a preparation method of the flexible three-dimensional network structure alkaline polyelectrolyte membrane, which is characterized by comprising the following steps:

a) Under the action of a first solvent and a catalyst, carrying out condensation polymerization on spirobifluorene, an aryl monomer and a ketone monomer through a Friedel-crafts reaction to obtain a network structure polymer;

The spirobifluorene, aryl monomers and ketone monomers are subjected to condensation polymerization through Friedel-crafts reaction under the action of a first solvent and a catalyst to obtain the network structure polymer.

In the invention, the aryl monomer is one or more of biphenyl, p-terphenyl and m-terphenyl; the ketone monomer is one or more of N-methyl-4-piperidone, 2-trifluoro acetophenone, indolone and 1, 1-trifluoroacetone, and derivatives of the ketone monomer; the-Cl, -Br or-I group carried by the ketone monomer can react with the cation functionalized micromolecule; the first solvent is one or more of dichloromethane, trichloromethane and 1, 2-dichloroethane; the catalyst is a super acid catalyst, preferably trifluoroacetic acid and/or trifluoromethanesulfonic acid.

In the present invention, the molar ratio of spirobifluorene to the aryl monomer is preferably (0.1 to 1): 1, more preferably (0.2 to 0.8): 1, such as 0.1:1,0.2:1,0.3:1,0.4:1,0.5:1,0.6:1,0.7:1,0.8:1,0.9:1,1:1, preferably a range value having any of the above numerical values as an upper limit or a lower limit; the increase of the spirobifluorene content can increase the rigidity and reduce the flexibility of the material, and the excessive spirobifluorene content can cause that the colloid required by the subsequent reaction can not be formed.

The molar ratio of the aryl monomer to the ketone monomer is preferably 1: (1 to 1.5), more preferably 1: (1.1 to 1.4), such as 1,1.1, 1,1.2, 1,1.3, 1; the volume ratio of the first solvent to the catalyst is preferably (0 to 2): 1, more preferably (0.5 to 1.5): 1, such as 0.1:1,0.5:1,1:1,1.5:1,2:1, preferably a range value having any of the above numerical values as an upper limit or a lower limit; the ratio of the total molar amount of the spirobifluorene, the aryl monomer and the ketone monomer to the volume of the first solvent is (0.3-1) mol:100mL, more preferably (0.4 to 0.6) mol:100mL, such as 0.3mol:100mL,0.4mol:100mL,0.5mol:100mL,0.6mol:100mL,0.7mol:100mL,0.8mol:100mL,0.9mol:100mL,1mol:100mL, preferably a range value having any of the above values as the upper limit or the lower limit.

In the present invention, the temperature of the polycondensation reaction is preferably-5 to 30 ℃, more preferably 0 to 25 ℃, such as-5 ℃,0 ℃,5 ℃,10 ℃,15 ℃,20 ℃,25 ℃,30 ℃, preferably a range value with any of the above values as an upper limit or a lower limit; the time of the polycondensation reaction is preferably 0.5 to 48 hours, more preferably 1 to 36 hours, such as 0.5 hour, 1 hour, 5 hours, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, 48 hours, and preferably a value in the range of any of the above values as the upper limit or the lower limit.

After the network structure polymer is obtained, the network structure polymer is added into a second solvent, and after the polymer is fully swelled, the mixture is heated and vigorously stirred until a uniform colloid is formed. And then adding the cation functionalized micromolecules and an acid-binding agent into the formed colloid mixture for functionalization reaction, and purifying and drying reactants to obtain the anion functionalized polymer.

In the invention, the second solvent is one or more of N, N-dimethylformamide, N-diethylformamide, dimethyl sulfoxide and N-methylpyrrolidone; the second solvent can ensure that the system before and after the functionalization reaction is in a uniform and transparent colloid state.

The cation functionalized micromolecule is preferably any one of precursor molecules capable of generating cations of quaternary ammonium salts, quaternary phosphine salts, imidazole salts and piperidine salts and derivatives thereof, and is more preferably one or more of methyl iodide, trimethylamine, N-methylimidazole and N-methylpiperidine. The acid-binding agent is one or more of anhydrous potassium carbonate, triethylamine, pyridine and diisopropylethylamine.

In the present invention, the ratio of the mass of the network-structured polymer to the volume of the second solvent is preferably (2 to 5) g:100mL, more preferably (3 to 4) g:100mL, such as 2g:100mL,3g:100mL,4g:100mL,5g:100mL, preferably a range value having any of the above numerical values as the upper limit or the lower limit; the mole ratio of the network structure polymer to the cationic functionalized micromolecule is preferably (0.5-2): 1, more preferably (1 to 1.5): 1, such as 0.5:1,0.6:1,0.7:1,0.8:1,0.9:1,1:1,1.1:1,1.2:1,1.3:1,1.4:1,1.5:1,1.6:1,1.7:1,1.8:1,1.9:1,2:1, preferably a range value having any of the above numerical values as an upper limit or a lower limit; the mole ratio of the acid-binding agent to the cation functionalized micromolecules is preferably (1-4): 1, more preferably (2 to 3): 1.

in the present invention, the heating is preferably carried out at 60 to 120 ℃ and the vigorous stirring is carried out to form a uniform colloid, more preferably 70 to 110 ℃, such as 60 ℃,70 ℃,80 ℃,90 ℃,100 ℃,110 ℃,120 ℃, and preferably a range value with any of the above values as the upper limit or the lower limit; the temperature of the functionalization reaction is preferably 25-120 ℃, more preferably 50-100 ℃, such as 25 ℃,30 ℃,40 ℃,50 ℃,60 ℃,70 ℃,80 ℃,90 ℃,100 ℃,110 ℃ and 120 ℃, and is preferably a range value taking any value as an upper limit or a lower limit; the time for the functionalization reaction is preferably 1 to 3 days, more preferably 1 to 2 days. The regulation and control of the ion exchange capacity of the anion functionalized polymer can be realized by changing the reaction time and the reaction temperature.

After the anion functionalized polymer is obtained, the obtained anion functionalized polymer is added into a third solvent, and is heated and stirred vigorously until a uniform colloid is formed. Coating the obtained colloid on a substrate, drying and curing to obtain an alkaline polyelectrolyte membrane, soaking the obtained electrolyte membrane in an ion exchange solution containing different anions for ion exchange, and then washing with deionized water to obtain the alkaline polyelectrolyte membrane accompanied with different anions.

In the invention, the third solvent is one or more of N, N-dimethylformamide, N-diethylformamide, dimethyl sulfoxide and N-methylpyrrolidone; the anion exchange solution is preferably a strong electrolyte solution containing the desired anion, more preferably comprising NaOH, KOH, naCl, KCl, naBr, KBr, naSO ₄ And NaCO ₃ In one ofOr a plurality of the components; the concentration of the anion exchange solution is preferably 0.5 to 5mol/L, more preferably 1 to 4mol/L, such as 0.5mol/L,1mol/L,1.5mol/L,2mol/L,2.5mol/L,3mol/L,3.5mol/L,4mol/L,4.5mol/L,5mol/L, and is preferably a range value having any of the above values as an upper limit or a lower limit.

In the present invention, the ratio of the mass of the anion-functional polymer to the volume of the third solvent is preferably (1 to 10) g:100mL, more preferably (2 to 8) g:100mL, such as 1g:100mL,2g:100mL,3g:100mL,4g:100mL,5g:100mL,6g:100mL,7g:100mL,8g:100mL,9g:100mL,10g:100mL, preferably a range value having any of the above values as the upper limit or the lower limit. The thickness of the polyelectrolyte membrane can be regulated and controlled by changing the concentration and the coating amount of the membrane liquid. In the present invention, the thickness of the basic polyelectrolyte membrane is preferably 4 to 400 μm.

In the present invention, the heating is preferably carried out at 60 to 120 ℃ and the vigorous stirring is carried out to form a uniform colloid, more preferably 70 to 110 ℃, such as 60 ℃,70 ℃,80 ℃,90 ℃,100 ℃,110 ℃,120 ℃, and preferably a range value with any of the above values as the upper limit or the lower limit; the temperature for drying and curing is preferably 25 to 80 ℃, more preferably 30 to 70 ℃, such as 25 ℃,30 ℃,40 ℃,50 ℃,60 ℃,70 ℃ and 80 ℃, and preferably ranges from any of the above values as upper limit or lower limit.

In the present invention, the ion exchange is performed with OH ^- Ion exchange, taking care to isolate air to avoid CO in air ₂ The influence of (c). The time for the ion exchange is preferably 12 to 36 hours, more preferably 18 to 24 hours, and the anion exchange solution is preferably replaced every 1 to 3 hours.

Often, polymers that are too rigid or have a network structure are generally poorly soluble, and therefore face difficulties in functionalization and subsequent processing. In the invention, because the designed molecular structure contains a rigid structure and a flexible chain segment, the material has certain flexibility and elasticity, and can form uniform colloid in a proper solvent through heating and violent stirring. The reactions in step B) and step C) are carried out in colloid, and attention needs to be paid to carrying out subsequent reactions after the formed colloid is completely uniform and transparent, so that the effect same as that of solution reaction can be achieved, and otherwise, the reaction yield can be influenced.

The invention provides a flexible three-dimensional network structure alkaline polyelectrolyte membrane, which is obtained by ion exchange after an anion functionalized polymer is formed into a membrane; the anion functionalized polymer has a structure shown in a formula I or a formula II. The invention designs an alkaline polyelectrolyte membrane with a flexible three-dimensional network structure, and the material has the micropore characteristic of a rigid material and the excellent processability of a flexible material. The spirobifluorene unit with a non-coplanar twisted structure in the polymer serves as a rigid network node to force the molecular chain segments to extend towards different directions, so that a loose network structure is formed, and a large amount of free volume and micropores are formed. The free volume and the micropores can be used as high-efficiency channels for ion selective transmission, so that the prepared alkaline polyelectrolyte membrane has very excellent ion conduction capability and OH at 80 DEG C ^- The ionic conductivity can reach 150mS/cm, cl ^- SO ₄ ^2- The conductivity of the anion with equal volume can reach 100mS/cm, which is more than one time higher than that of the commercial alkaline membrane AMV on the market. On the other hand, the polymer with over-strong rigidity or network structure usually faces the problem that the polymer can not be dissolved so as to be difficult to carry out subsequent functionalization and processing to form a film, but the rest parts of the main chain of the polymer prepared by the invention are connected by the aromatic hydrocarbon and the flexible methylene which can rotate, so that the formed three-dimensional network polymer has certain flexibility and elasticity, can be fully swelled in a solvent to form uniform colloid, is convenient for carrying out modification and functionalization reactions, has excellent processability, and overcomes the obstruction of the polymer with similar structure to the subsequent reaction and processing due to poor solubility. The prepared alkaline polyelectrolyte membrane has excellent mechanical strength, and the tensile strength at room temperature is higher than 20MPa. In addition, the full-carbon main chain synthesized by the super-strong acid catalytic reaction avoids sensitive polar groups such as aryl ether bond and the like, so that the prepared alkaline polyelectrolyte membrane has excellent chemical stability and can be used for a long time in a NaOH solution of 1mol/L at 80 DEG CAfter the intermediate soaking, the ion exchange capacity and the conductivity retention rate are maintained to be more than 90 percent.

In order to further illustrate the present invention, the following examples are provided to describe the flexible three-dimensional network structure alkaline polyelectrolyte membrane and the preparation method thereof in detail, but should not be construed as limiting the scope of the present invention.

Tensile Strength test

The anion-exchange membranes in the examples were tested for tensile strength at room temperature using a dynamic mechanical analyzer (model: Q800, manufacturer: TA Instrunebts).

Ion conductivity test

The ionic conductivity of the membrane in a full-wet state is tested by adopting a four-electrode alternating-current impedance method on the alkaline polyelectrolyte membrane obtained in the embodiment, and the specific test requirements and parameters are as follows: taking a membrane material with the length of 4cm, the width of 1cm and the thickness of 40um, repeatedly washing the membrane material with deionized water for 24 hours after exchanging the required accompanying ions, using an Autolab PGSTAT 30 electrochemical testing system to perform an alternating current impedance test within the frequency of 100Hz-1MHz, and recording the ionic conductance of the membrane in pure water.

Chemical stability test

The alkaline polyelectrolyte membrane prepared in the embodiment is soaked in 1mol/L sodium hydroxide solution at the temperature of 80 ℃, samples are taken out at intervals, and after the redundant sodium hydroxide solution is repeatedly washed by deionized water, the ion exchange capacity and the conductivity residual rate of the membrane are tested.

Example 1

The embodiment provides a three-dimensional network structure alkaline polyelectrolyte membrane, which has the following preparation structure:

(1) And (3) synthesizing a polymer. 2.8476g (9 mmol) of spirobifluorene, 6.4764g (42 mmol) of biphenyl and 8.1482g (72 mmol) of N-methyl-4-piperidone were weighed into a 100mL round-bottomed flask, 30mL of methylene chloride was added, 10mL of trifluoroacetic acid and 50mL of trifluoromethanesulfonic acid were slowly added dropwise at 0 ℃ respectively, and the reaction temperature was maintained at 0 ℃ for 3 hours. And precipitating the product in NaOH solution, fully washing the product with deionized water, filtering the solution to obtain a white solid, and drying the white solid in an oven at the temperature of 60 ℃ for 24 hours to obtain the polymer with the three-dimensional network structure.

(2) And (4) functionalizing the polymer. 5.0g (20 mmol) of the above-mentioned initial polymer was weighed in a mixed solvent of 200mL of LN-methylpyrrolidone and dimethylsulfoxide, and after it was sufficiently swollen, it was vigorously stirred at 80 ℃ until the system formed a pale yellow homogeneous colloid. Subsequently, 5.528g (40 mmol) of potassium carbonate and 5.6776g (40 mmol) of methyl iodide were added, and the reaction was carried out at 30 ℃ for 72 hours. And pouring the reaction product into acetone for precipitation to obtain yellow precipitate, washing with acetone for several times, then washing with water and drying to obtain the anion functionalized polymer.

(3) And (3) preparing the alkaline polyelectrolyte membrane. 1g of the above anion functionalized polymer is weighed, added into 20mL of dimethyl sulfoxide, and stirred vigorously at 80 ℃ until the system forms a uniform and transparent colloid. And after impurities are removed by centrifugation, the obtained uniform and transparent colloidal solution is coated on a glass plate, and is dried at 60 ℃ to form a film, and the film is peeled from the glass plate. Soaking the membrane in 1M NaCl solution, and performing ion exchange at 30 deg.C for 24 hr to obtain Cl accompanied with anion ^- The basic polyelectrolyte membrane of (1).

The unique flexible three-dimensional network structure formed by the rigid spirobifluorene distorted nodes and the flexible chain segments ensures that the prepared network structure polymer has the micropore characteristic of a rigid material and the processability of a flexible material. As shown in FIG. 2, the alkaline polyelectrolyte membrane prepared by anion functionalization and processing into membrane has excellent mechanical property and tensile strength of 22MPa.

As shown in fig. 3, since the formed micropores can serve as channels for efficient ion transport, therefore, the prepared alkaline polyelectrolyte membrane has excellent ion conductivity and Cl at 30 DEG C ^- The ionic conductivity can reach 59mS/cm and can reach 106mS/cm at the temperature of 80 ℃. In addition, the main chain structure of the alkaline polyelectrolyte membrane prepared by the method is an all-carbon structure, and the alkaline polyelectrolyte membrane has excellent chemical stability.

As shown in FIG. 4, the conductivity retention rate of the prepared alkaline polyelectrolyte membrane is maintained to be more than 92% after the membrane is soaked in 1mol/L NaOH solution at 80 ℃ for 1000 h.

Example 2

This example is different from example 1 only in that 2.8476g (9 mmol) of spirobifluorene and 6.4764g (42 mmol) of biphenyl used in step (1) of example 1 were replaced with 1.8984g (6 mmol) of spirobifluorene and 7.4016g (48 mmol) of biphenyl during the preparation of a basic polyelectrolyte membrane, and the remaining preparation method was the same as in example 1.

Cl of the obtained alkaline polyelectrolyte membrane at 30 DEG C ^- The ionic conductivity can reach 54mS/cm, 104mS/cm at 80 ℃, the conductivity retention rate can be maintained at more than 93 percent after the material is soaked in 1mol/L NaOH solution at 80 ℃ for 1000 hours, and the tensile strength can reach 25MPa.

Example 3

The difference from example 1 is only that 2.8476g (9 mmol) of spirobifluorene and 6.4764g (42 mmol) of biphenyl employed in step (1) of example 1 were replaced with 0.9492g (3 mmol) of spirobifluorene and 8.3268g (54 mmol) of biphenyl during the preparation of the basic polyelectrolyte membrane, and the rest of the preparation method was the same as in example 1.

Cl of the resulting alkaline polyelectrolyte membrane at 30 deg.C ^- The ionic conductivity can reach 51mS/cm, the ionic conductivity can reach 102mS/cm at the temperature of 80 ℃, the conductivity retention rate is maintained to be more than 96 percent after the material is soaked in 1mol/L NaOH solution at the temperature of 80 ℃ for 1000 hours, and the tensile strength can reach 30MPa.

Example 4

The only difference from example 1 is that 2.8476g (9 mmol) of spirobifluorene and 6.4764g (42 mmol) of biphenyl used in step (1) of example 1 were replaced with 3.7968g (12 mmol) of spirobifluorene and 5.5512g (36 mmol) of biphenyl during the preparation of basic polyelectrolyte membrane, and the other preparation methods were the same as example 1.

Cl of the obtained alkaline polyelectrolyte membrane at 30 DEG C ^- The ionic conductivity can reach 62mS/cm, the ionic conductivity can reach 111mS/cm at 80 ℃, the conductivity retention rate can be maintained above 90 percent after the ionic conductivity can be soaked in 1mol/L NaOH solution at 80 ℃ for 1000 hours, and the tensile strength can reach 20MPa.

Example 5

(1) And (3) synthesizing a polymer. 2.8476g (9 mmol) of spirobifluorene, 6.4764g (42 mmol) of biphenyl and 13.5468g (72 mmol) of 4- (trifluoroacetyl) toluene were weighed into a 100mL round bottom flask, 40mL of dichloromethane was added, slowly added dropwise at 0 ℃ and 40mL of trifluoromethanesulfonic acid, and the reaction temperature was maintained at 0 ℃ for 3 hours. And precipitating the product in NaOH solution, fully washing the product with deionized water, filtering the solution to obtain a white solid, and drying the white solid in an oven at the temperature of 60 ℃ for 24 hours to obtain the polymer with the three-dimensional network structure.

(2) And (4) functionalizing the polymer. 5.0g of the above-mentioned initial polymer was weighed into 150mL of chlorobenzene, vigorously stirred at 130 ℃ to form a uniform colloid, and 1 equivalent of N-bromosuccinimide and azobisisobutyronitrile were added thereto and reacted for 4 hours. And pouring the reaction product into 1000mL of ethanol for precipitation to obtain a white precipitate, washing the white precipitate with ethanol for multiple times, and performing suction filtration and drying to obtain the brominated polymer. Then 1.62g (3 mmol) of the above-mentioned brominated polymer, 0.5852 (6 mmol) of N-methylpiperidine and 2.4877g (18 mmol) of potassium carbonate are weighed into 200mL of N-methylpyrrolidone, likewise homogeneously gelled, reacted at 100 ℃ for 3 days, the reaction product is precipitated into diethyl ether to give a yellow precipitate, which is washed several times with diethyl ether and instead washed with water and dried to give the anion-functionalized polymer.

(3) And (3) preparing the alkaline polyelectrolyte membrane. 1g of the anionic functional polymer is weighed and added into 20mL of dimethyl sulfoxide, and the mixture is stirred vigorously at 80 ℃ until a uniform and transparent colloid is formed in the system. And after impurities are removed by centrifugation, the obtained uniform and transparent colloidal solution is coated on a glass plate, and is dried at 60 ℃ to form a film, and the film is peeled from the glass plate. The membrane was immersed in 1M NaCl solution and ion exchanged at 30 ℃ for 24 hours to obtain Cl as a concomitant anion ^- The alkaline polyelectrolyte membrane of (1).

Cl of the resulting alkaline polyelectrolyte membrane at 30 deg.C ^- The ionic conductivity can reach 48mSPer cm, can reach 101mS/cm at 80 ℃, and the conductivity retention rate is maintained to be more than 95 percent after the glass fiber is soaked in 1mol/L NaOH solution at 80 ℃ for 1000 hours, and the tensile strength can reach 20MPa.

Example 6

The difference from example 5 is only that 2.8476g (9 mmol) of spirobifluorene and 6.4764g (42 mmol) of biphenyl employed in step (1) of example 5 were replaced with 1.8984g (6 mmol) of spirobifluorene and 7.4016g (48 mmol) of biphenyl during the preparation of the basic polyelectrolyte membrane, and the rest of the preparation method was the same as in example 5.

Cl of the obtained alkaline polyelectrolyte membrane at 30 DEG C ^- The ionic conductivity can reach 59mS/cm, the ionic conductivity can reach 115mS/cm at 80 ℃, the conductivity retention rate can be maintained to be more than 91 percent after the ionic conductivity is soaked in 1mol/L NaOH solution at 80 ℃ for 1000 hours, and the tensile strength can reach 21MPa.

Example 7

The difference from example 5 is only that 2.8476g (9 mmol) of spirobifluorene and 6.4764g (42 mmol) of biphenyl employed in step (1) of example 5 were replaced with 0.9492g (3 mmol) of spirobifluorene and 8.3268g (54 mmol) of biphenyl during the preparation of the basic polyelectrolyte membrane, and the rest of the preparation method was the same as in example 1.

Cl of the obtained alkaline polyelectrolyte membrane at 30 DEG C ^- The ionic conductivity can reach 45mS/cm, the ionic conductivity can reach 98mS/cm at 80 ℃, the conductivity retention rate can be maintained to be more than 97 percent after the ionic conductivity is soaked in 1mol/L NaOH solution at 80 ℃ for 1000 hours, and the tensile strength can reach 29MPa.

Example 8

(1) And (3) synthesizing a polymer. 2.8476g (9 mmol) of spirobifluorene, 9.637g (42 mmol) of terphenyl and 8.1482g (72 mmol) of N-methyl-4-piperidone were weighed into a 100mL round-bottomed flask, 30mL of dichloromethane was added, 10mL of trifluoroacetic acid and 50mL of trifluoromethanesulfonic acid were slowly added dropwise at 0 ℃ respectively, and the reaction temperature was maintained at 0 ℃ for 3 hours. And precipitating the product in NaOH solution, fully washing the product with deionized water, filtering the solution to obtain a white solid, and drying the white solid in an oven at the temperature of 60 ℃ for 24 hours to obtain the polymer with the three-dimensional network structure.

(2) And (4) functionalizing the polymer. 5.935g (20 mmol) of the initial polymer is weighed into a mixed solvent of 200 mLN-methyl pyrrolidone and dimethyl sulfoxide, and stirred vigorously at 80 ℃ until the system forms a light yellow uniform colloid after the initial polymer is fully swelled. Subsequently, 5.528g (40 mmol) of potassium carbonate and 5.6776g (40 mmol) of methyl iodide were added and reacted at 30 ℃ for 72 hours. And pouring the reaction product into acetone for precipitation to obtain yellow precipitate, washing with acetone for several times, then washing with water and drying to obtain the anion functionalized polymer.

(3) And (3) preparing the alkaline polyelectrolyte membrane. 1g of the anionic functional polymer is weighed and added into 20mL of dimethyl sulfoxide, and the mixture is stirred vigorously at 80 ℃ until a uniform and transparent colloid is formed in the system. And after impurities are removed by centrifugation, the obtained uniform and transparent colloidal solution is coated on a glass plate, and is dried at 60 ℃ to form a film, and the film is peeled from the glass plate. Soaking the membrane in 1M NaOH solution, and performing ion exchange at 30 deg.C for 24 hr to obtain anion with OH ^- The alkaline polyelectrolyte membrane of (1).

OH of the obtained alkaline polyelectrolyte membrane at 30 DEG C ^- The ionic conductivity can reach 75mS/cm, the ionic conductivity can reach 150mS/cm at 80 ℃, the conductivity retention rate can be maintained above 95% after the ionic conductivity is soaked in 1mol/L NaOH solution at 80 ℃ for 1000 hours, and the tensile strength can reach 25MPa.

Example 9

The only difference from example 8 is that 2.8476g (9 mmol) of spirobifluorene and 9.637g (42 mmol) of terphenyl used in step (1) of example 8 were changed to 0.9492g (3 mmol) of spirobifluorene and 12.391g (54 mmol) of terphenyl during the preparation of basic polyelectrolyte membrane, and the other preparation methods were the same as example 1.

OH of the obtained alkaline polyelectrolyte membrane at 30 DEG C ^- The ionic conductivity can reach 68mS/cm, the ionic conductivity can reach 141mS/cm at the temperature of 80 ℃, and the conductivity retention rate is maintained at 93 percent after the ionic conductivity is soaked in 1mol/L NaOH solution at the temperature of 80 ℃ for 1000 hoursAnd the tensile strength can reach 27MPa.

Example 10

The difference from example 8 is only that 2.8476g (9 mmol) of spirobifluorene and 9.637g (42 mmol) of terphenyl used in step (1) of example 8 were changed to 1.8984g (6 mmol) of spirobifluorene and 11.014g (48 mmol) of terphenyl during the preparation of basic polyelectrolyte membrane, and the rest of the preparation method was the same as example 1.

OH of the obtained alkaline polyelectrolyte membrane at 30 DEG C ^- The ionic conductivity can reach 65mS/cm, the ionic conductivity can reach 135mS/cm at 80 ℃, the conductivity retention rate can be maintained above 96 percent after the material is soaked in 1mol/L NaOH solution at 80 ℃ for 1000 hours, and the tensile strength can reach 32MPa.

Example 11

The difference from example 8 is only that 9.637g (42 mmol) of terphenyl used in step (1) of example 8 was changed to 9.637g (42 mmol) of m-terphenyl during the preparation of the basic polyelectrolyte membrane, and the remaining preparation method was the same as in example 1.

OH of the obtained alkaline polyelectrolyte membrane at 30 DEG C ^- The ionic conductivity can reach 72mS/cm, the ionic conductivity can reach 148mS/cm at the temperature of 80 ℃, the conductivity retention rate is maintained to be more than 96 percent after the material is soaked in 1mol/L NaOH solution at the temperature of 80 ℃ for 1000 hours, and the tensile strength can reach 35MPa.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A flexible alkaline polyelectrolyte membrane with a three-dimensional network structure is obtained by ion exchange after an anion functionalized polymer is formed into a membrane;

r is selected from one of the formulas 3 to 7, and R is an integer of 1 to 10;

2. The method for preparing the basic polyelectrolyte membrane with the flexible three-dimensional network structure according to claim 1, comprising the following steps:

3. The preparation method according to claim 2, wherein in the step a), the aryl monomer is one or more of biphenyl, p-terphenyl and m-terphenyl;

the catalyst is trifluoroacetic acid and/or trifluoromethanesulfonic acid.

4. The method according to claim 4, wherein the molar ratio of spirobifluorene to the aryl monomer is (0.1-1): 1; the molar ratio of the aryl monomer to the ketone monomer is 1: (1-1.5); the volume ratio of the first solvent to the catalyst is (0-2): 1, and the ratio of the total molar amount of the spirobifluorene, the aryl monomer and the ketone monomer to the volume of the first solvent is (0.3-1) mol:100mL.

5. The method according to claim 4, wherein the temperature of the polycondensation is-5 to 30 ℃ and the time of the polycondensation is 0.5 to 48 hours.

6. The preparation method according to claim 2, wherein the second solvent is one or more of N, N-dimethylformamide, N-diethylformamide, dimethyl sulfoxide and N-methylpyrrolidone;

7. The production method according to claim 6, wherein the ratio of the mass of the network-structured polymer to the volume of the second solvent is (2 to 5) g:100mL; the molar ratio of the network structure polymer to the cationic functional micromolecules is (0.5-2): 1; the molar ratio of the acid-binding agent to the cationic functionalized micromolecules is (1-4): 1.

8. the method according to claim 7, wherein the temperature of the reaction in step B) is 25 to 120 ℃; the reaction time in the step B) is 1 to 3 days.

9. The preparation method according to claim 2, wherein the third solvent is one or more of N, N-dimethylformamide, N-diethylformamide, dimethyl sulfoxide and N-methylpyrrolidone;

10. The method according to claim 9, wherein the ion exchange is performed under air exclusion for 12 to 36 hours, and the anion exchange solution is replaced every 1 to 3 hours.