阅读说明：本技术 一种聚酯类刷形聚合物、其一锅法合成方法及应用 (Polyester brush-shaped polymer, one-pot synthesis method and application thereof ) 是由 薛志刚 郭楷瑞 李少桥 王计嵘 周兴平 解孝林 于 2021-07-13 设计创作，主要内容包括：本发明属于锂离子电池聚合物电解质领域,更具体地,涉及一种聚酯类刷形聚合物、其一锅法合成方法及应用。在无水无氧条件下,将甲基丙烯酸羟乙酯单体和环内酯单体混合均匀,形成单体混合物；将单体混合物与自由基引发剂和链转移试剂4-氰基-4-(硫代苯甲酰)戊酸混合,获得原料混合液,将原料混合液,在惰性气氛下升温使得甲基丙烯酸羟乙酯单体发生可逆加成-断裂转移聚合,使得环内酯单体开环聚合反应,分离后得到所述聚酯类刷形共聚物。该方法结合了可控/“活性”自由基聚合中的可逆加成-断裂链转移聚合反应和有机酸催化羟基引发环状酯类单体的开环聚合反应,在一锅中实现了从小分子到刷形聚合物的合成。(The invention belongs to the field of lithium ion battery polymer electrolytes, and particularly relates to a polyester brush polymer, a one-pot synthesis method and application thereof. Uniformly mixing hydroxyethyl methacrylate monomers and cyclic lactone monomers under anhydrous and anaerobic conditions to form a monomer mixture; mixing the monomer mixture with a free radical initiator and a chain transfer reagent 4-cyano-4- (thiobenzoyl) valeric acid to obtain a raw material mixed solution, heating the raw material mixed solution in an inert atmosphere to enable hydroxyethyl methacrylate monomer to generate reversible addition-fragmentation transfer polymerization so as to enable cyclic lactone monomer to perform ring-opening polymerization reaction, and separating to obtain the polyester brush-shaped copolymer. The method combines the reversible addition-fragmentation chain transfer polymerization reaction in the controllable/'active' free radical polymerization and the ring-opening polymerization reaction of the cyclic ester monomer initiated by hydroxyl catalyzed by organic acid, and realizes the synthesis of the polymer from small molecules to brush shape in one pot.)

1. A preparation method of a polyester brush polymer is characterized by comprising the following steps:

(1) uniformly mixing hydroxyethyl methacrylate monomers and cyclic lactone monomers under anhydrous and anaerobic conditions to form a monomer mixture;

(2) mixing the monomer mixture obtained in the step (1) with a free radical initiator and a chain transfer reagent to obtain a raw material mixed solution, wherein the chain transfer reagent is 4-cyano-4- (thiobenzoyl) valeric acid;

(3) heating the raw material mixed solution obtained in the step (2) in an inert atmosphere to enable the hydroxyethyl methacrylate monomer to generate reversible addition-fragmentation transfer polymerization, so that the cyclic lactone monomer is subjected to ring-opening polymerization reaction; after the reaction is finished, cooling to room temperature to quench the reaction to obtain a crude product, and separating to obtain the polyester brush copolymer.

2. The method of claim 1, wherein the cyclic lactone monomer is one or more of epsilon-caprolactone, delta-valerolactone, DL-lactide, and trimethylene carbonate.

3. The method of claim 1, wherein the free radical initiator is one or more of azobisisobutyronitrile, azobisisoheptonitrile, dibenzoyl peroxide, and lauroyl peroxide.

4. The preparation method according to claim 1, wherein the charging molar ratio of the cyclic lactone monomer and the hydroxyethyl methacrylate monomer in the step (1) is 10-30: 1; the feeding molar ratio of the hydroxyethyl methacrylate in the step (1) to the chain transfer reagent 4-cyano-4- (thiobenzoyl) valeric acid in the step (2) is 40-80: 1.

5. The method of claim 1, wherein the feeding molar ratio of the free radical initiator to the chain transfer agent 4-cyano-4- (thiobenzoyl) pentanoic acid in the step (2) is 1:3 to 1: 5.

6. The preparation method according to claim 1, wherein in the step (3), the temperature is increased to 50-90 ℃ for reaction for 12-36 hours to allow the hydroxyethyl methacrylate monomer to undergo reversible addition-fragmentation transfer polymerization, and then the temperature is increased to 110-150 ℃ for reaction for 16-48 hours to allow the cyclic lactone monomer to undergo ring-opening polymerization.

7. A polyester brush polymer is characterized in that the main chain of the polymer is a polymethacrylate chain, and polyester side chains are grafted on the main chain of the polymer; the polymer has a structural formula shown as a formula (I):

wherein X represents a part except an ester group in a cyclic lactone monomer structure, n is an integer of 10-30, and m is an integer of 40-80.

8. The use of a polyester brush polymer according to claim 7 for the preparation of an electrolyte membrane for a lithium ion battery.

9. The use according to claim 8, wherein the electrolyte membrane is prepared by the following method: dissolving the polyester brush-shaped polymer and lithium salt in a solvent according to the mass ratio of the polymer to the lithium salt of 2: 1-7: 1 to obtain a mixed solution, and then preparing the polymer electrolyte membrane by adopting a solution casting method.

10. The use according to claim 9, wherein the solvent is one or more of tetrahydrofuran, acetonitrile, N-methylpyrrolidone, N-dimethylformamide and dimethylsulfoxide; the lithium salt is one or more of bis (trifluoromethyl) sulfonyl imide lithium, lithium perchlorate and lithium hexafluorophosphate.

Technical Field

The invention belongs to the field of lithium ion battery polymer electrolytes, and particularly relates to a polyester brush polymer, a one-pot synthesis method and application thereof.

Background

Lithium ion batteries are gaining popularity due to their advantages of being lightweight, rechargeable, and having high power and energy densities. The traditional commercial lithium ion battery mostly adopts liquid electrolyte systems such as organic carbonates, and the like, and has the defects that a liquid solvent is easy to leak, lithium dendrite generated after circulation causes battery short circuit and the like in the use process. Thus, people have looked to safer and more stable solid polymer electrolytes. All-solid-state polymer electrolytes (ASSPEs) are expected to overcome the defects of liquid electrolytes due to the advantages of good safety performance, excellent flexibility and mechanical properties, wide working temperature range and the like, and further meet the requirements of commercial application. The polyester polymer electrolyte-based all-solid-state lithium ion battery has a wide working range interval, and can provide guarantee for the cycle performance of the battery. However, the ionic conductivity of linear polyesters is generally low due to their semicrystalline nature.

The brush polymer is a graft polymer with a comb-like shape, a main chain is formed by a repeating structural unit, and a side chain of the brush polymer is tightly connected to a macromolecular main chain through a covalent bond. Due to the strong steric repulsion between the side chains, the main chain is forced to stretch by the side chain action, and the entire macromolecule exhibits a worm-like structure with a compact molecular size. The brush polymer has attracted extensive attention of researchers due to its compact graft structure, and is widely applied to the field of all-solid-state electrolyte and other material science. By constructing the brush-shaped polyester polymer, the regularity of a polyester chain segment can be destroyed and the semi-crystallinity of the polyester chain segment can be inhibited due to the special grafting structure of the brush-shaped polyester polymer, so that the ion conductivity of the polyester polymer electrolyte is improved.

Currently, polymer brushes are typically synthesized by three methods (chem. eur. j.2019,25,8177-8189), namely "grafting through" (polymerization of macromers), "grafting to" (attachment of pre-synthesized polymer chains to a substrate) and "grafting from" (direct initiation of monomer polymerization from an initiation point on the substrate). The backbone and side chain polymers of the polymer brush can be prepared by a pre-controlled polymerization process such as living/controlled radical polymerization, ring-opening polymerization, and anionic polymerization. However, how to conveniently and rapidly synthesize the polymer, precisely regulate and control the lengths of the main chain and the side chain of the polymer and realize good molecular weight distribution control is still a problem at present. For example, the royal navy topic of the university of Hebei has been combined into a polycaprolactone grafted polymer brush (J.Polym.Res.2016,23,31) based on ring-opening polymerization and click reaction, but the preparation process needs to distribute and synthesize a main chain containing an azido functional group and a polycaprolactone side chain containing an alkynyl group. As can be seen, the synthesis of traditional brush polymers usually requires a step-by-step process, and there is still a lack of research on the synthesis of brush polymers by a one-pot process.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a method for preparing a polyester brush-shaped polymer electrolyte by a one-pot method, and aims to solve the technical problems that the polyester brush-shaped polymer electrolyte in the prior art needs to be realized by a step-by-step feeding method, is complex in preparation method, is uncontrollable in reaction and the like.

In order to achieve the above object, the present invention provides a method for preparing a polyester brush polymer, comprising the steps of:

(1) uniformly mixing hydroxyethyl methacrylate monomers and cyclic lactone monomers under anhydrous and anaerobic conditions to form a monomer mixture;

(2) mixing the monomer mixture obtained in the step (1) with a free radical initiator and a chain transfer reagent to obtain a raw material mixed solution, wherein the chain transfer reagent is 4-cyano-4- (thiobenzoyl) valeric acid;

(3) heating the raw material mixed solution obtained in the step (2) in an inert atmosphere to enable the hydroxyethyl methacrylate monomer to generate reversible addition-fragmentation transfer polymerization, so that the cyclic lactone monomer is subjected to ring-opening polymerization reaction; after the reaction is finished, cooling to room temperature to quench the reaction to obtain a crude product, and separating to obtain the polyester brush copolymer.

In a preferred embodiment, the cyclic lactone monomer is one or more of epsilon-caprolactone, delta-valerolactone, DL-lactide and trimethylene carbonate.

In a preferred embodiment, the radical initiator is one or more of azobisisobutyronitrile, azobisisoheptonitrile, dibenzoyl peroxide and lauroyl peroxide.

In a preferable scheme, the chain transfer agent in the step (2) is 4-cyano-4- (thiobenzoyl) valeric acid containing carboxyl, a disulfide structure of the chain transfer agent can be used as a reversible addition-fragmentation chain transfer polymerization growth site of the main chain polyhydroxyethyl methacrylate, and an intramolecular organic acid structure can catalyze hydroxyl to initiate ring-opening polymerization of the cyclic ester monomer. The bifunctional chain transfer agent 4-cyano-4- (thiobenzoyl) pentanoic acid has the following structural formula:

in the preparation method, the hydroxyethyl methacrylate in the step (1) has dual functions, and the hydroxyl on the molecule can initiate ring-opening polymerization of the cyclic ester monomer while reversible addition-fragmentation chain transfer polymerization is carried out. The structural formula of the bifunctional molecular hydroxyethyl methacrylate is as follows:

in a preferable scheme, the feeding molar ratio of the cyclic lactone monomer and the hydroxyethyl methacrylate monomer in the step (1) is 10-30: 1; the feeding molar ratio of the hydroxyethyl methacrylate in the step (1) to the chain transfer reagent 4-cyano-4- (thiobenzoyl) valeric acid in the step (2) is 40-80: 1.

In a preferable scheme, the feeding molar ratio of the free radical initiator to the chain transfer reagent 4-cyano-4- (thiobenzoyl) valeric acid in the step (2) is 1: 3-1: 5.

In a preferable scheme, in the step (3), the temperature is firstly increased to 50-90 ℃ for reaction for 12-36 hours, so that the hydroxyethyl methacrylate monomer is subjected to reversible addition-fragmentation transfer polymerization, and then the temperature is increased to 110-150 ℃ for reaction for 16-48 hours, so that the cyclic lactone monomer is subjected to ring-opening polymerization.

In a preferred scheme, after the crude product is obtained in the step (3), tetrahydrofuran is adopted to dissolve the crude product to obtain a block copolymer solution; then adding the obtained block copolymer solution into anhydrous ether for precipitation, filtering and separating precipitate, and drying to obtain the polyester block copolymer.

In a preferable embodiment, the inert atmosphere in the step (3) is an argon atmosphere or a nitrogen atmosphere.

The invention also provides a polyester brush polymer, the main chain of the polymer is a polymethacrylate chain, and polyester side chains are grafted on the main chain of the polymer; the polymer has a structural formula shown as a figure 1 and a formula (I):

wherein X represents a part except an ester group in a cyclic lactone monomer structure, n is an integer of 10-30, and m is an integer of 40-80. Namely, the polymerization degree of the polyester side chain segment on one side is 10-30; the polymerization degree of the polymethacrylate main chain is 40-80.

In a preferred embodiment, the cyclic lactone monomer is one or more of epsilon-caprolactone, delta-valerolactone, DL-lactide and trimethylene carbonate, and correspondingly, the polyester side chain segment is one or more of polycaprolactone, polypentanolactone, polylactide and polytrimethylene carbonate.

Taking the polyester chain segment as polycaprolactone as an example, the polyester brush polymer has a structure shown as a formula (II):

wherein n is an integer of 10 to 30, and m is an integer of 40 to 80.

As a further preferred aspect of the present invention, the polymer represented by formula (II) has a synthetic route represented by formula (III):

wherein n is an integer of 10 to 30, and m is an integer of 40 to 80. CL (4) represents a caprolactone monomer and AIBN (5) represents azobisisobutyronitrile.

According to another aspect of the invention, the invention provides application of the polyester brush polymer in preparing an electrolyte membrane of a lithium ion battery.

In a preferred embodiment, the thickness of the electrolyte membrane is 50 to 100 μm.

In a preferred embodiment, the electrolyte membrane is prepared by the following method: dissolving the polyester brush-shaped polymer and lithium salt in a solvent according to the mass ratio of the polymer to the lithium salt of 2: 1-7: 1 to obtain a mixed solution, and then preparing the polymer electrolyte membrane by adopting a solution casting method.

In a preferred scheme, the solvent is one or more of tetrahydrofuran, acetonitrile, N-methylpyrrolidone, N-dimethylformamide and dimethyl sulfoxide; the lithium salt is one or more of bis (trifluoromethyl) sulfonyl imide lithium, lithium perchlorate and lithium hexafluorophosphate.

The invention discloses a polyester brush-shaped polymer-based electrolyte, and a one-pot preparation method and application thereof. By combining the characteristic that the organic carboxylic acid group in the 4-cyano-4- (thiobenzoyl) valeric acid can catalyze the ring-opening reaction of the hydroxy-initiated cyclic lactone, compared with an organic metal catalyst adopted in the traditional ring-opening polymerization reaction, the compound is greener and has better molecular weight distribution controllability. The chain structure of the brush-shaped polymer is adjusted by changing the types of the cyclic lactone monomers, the charging ratio, the temperature, the reaction time and other factors, and the obtained polymer has controllable molecular weight and narrow distribution. Compared with the prior art, the technical scheme of the invention can better solve the problems that the brush polymer is complicated to synthesize and the molecular weight and the distribution thereof are difficult to regulate and control. The prepared brush copolymer has controllable structure and good performance, and can be used for multiple purposes. The brush-shaped polyester polymer is applied to the field of all-solid-state electrolytes, and the regularity of polyester chain segments can be destroyed and the semi-crystallinity of the polyester chain segments can be inhibited by constructing the brush-shaped polyester polymer, so that the ion conduction capability of the polyester polymer electrolyte is improved.

In general, compared with the prior art, the above technical solution contemplated by the present invention can achieve the following beneficial effects:

(1) the invention provides a polyester brush polymer and a one-pot synthesis method thereof, which combines reversible addition-fragmentation chain transfer polymerization reaction in controllable/'active' free radical polymerization and ring-opening polymerization reaction of hydroxyl-initiated cyclic ester monomers catalyzed by organic acid, and realizes the synthesis of the brush polymer from small molecules in one pot.

(2) The polyester brush-shaped polymer designed by the invention has the characteristic of controllable structure, the chain structure of the brush-shaped polymer is adjusted by changing the types of the cyclic lactone monomers, the feeding ratio, the temperature, the reaction time and other factors, and the molecular weight of the obtained polymer is controllable and has narrow distribution. Compared with the prior art, the invention can synthesize the brush polymer more conveniently and simply.

(3) The method combines the characteristic that organic carboxylic acid groups in 4-cyano-4- (thiobenzoyl) valeric acid can catalyze the ring-opening reaction of the hydroxy-initiated cyclic lactone, and compared with an organic metal catalyst adopted in the traditional ring-opening polymerization reaction, the method is greener, and the molecular weight and the distribution controllability are high.

(4) The polyester brush polymer designed and synthesized by the invention obviously reduces the polyester polymer due to the comb structureCrystallinity and facilitates the migration and movement of lithium ions between side chains. The polymer electrolyte can be applied to the field of lithium ion batteries, can effectively improve the conductivity of polyester-based solid polymer electrolyte, and has the room-temperature conductivity as high as 4.1 multiplied by 10^-5S cm^-1。

Drawings

FIG. 1 is a schematic view showing the structure of a polyester brush polymer electrolyte according to the present invention.

FIG. 2 is a nuclear magnetic resonance spectrum of a polyester brush polymer synthesized in example 1 of the present invention.

FIG. 3 is a kinetic profile of a polyester-based brush polymer prepared in example 1 of the present invention.

Fig. 4 is a graph of temperature change conductivity of the polymer electrolyte prepared in example 1 of the present invention.

Fig. 5 is a graph showing lithium ion mobility of the polymer electrolyte prepared in example 1 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention discloses a polyester brush-shaped polymer-based electrolyte and one-pot preparation and application thereof. Compared with the prior art, the invention combines reversible addition-fragmentation chain transfer polymerization and organic acid catalyzed ring opening polymerization, can realize rapid synthesis from micromolecules to brush-shaped polymers in one pot, and realizes better molecular weight distribution controllability. Compared with the organic metal catalyst adopted in the traditional ring-opening polymerization reaction, the organic metal catalyst is more green and has stronger molecular weight distribution controllability by utilizing the characteristic that organic carboxylic acid groups in 4-cyano-4- (thiobenzoyl) valeric acid can catalyze the ring-opening reaction of the hydroxy-initiated cyclic lactone. The chain structure of the brush-shaped polymer is adjusted by changing the types of the cyclic lactone monomers, the charging ratio, the temperature, the reaction time and other factors, and the obtained polymer has controllable molecular weight and narrow distribution. The polyester brush polymer designed and synthesized by the invention obviously reduces the crystallinity of the polyester polymer due to the comb structure, and is beneficial to the migration and movement of lithium ions among side chains. Compared with the prior art, the technical scheme of the invention can better solve the problems that the synthesis of the polyester brush-shaped polymer is complicated, and the molecular weight and the distribution thereof are difficult to regulate and control. The conductive agent is applied to the field of lithium ion batteries, and can effectively improve the conductivity of polyester-based solid polymer electrolytes.

The structure of all polymers according to the invention is confirmed by NMR spectra and kinetic curves; the electrochemical performance of all the electrolyte membranes is verified by an electrochemical impedance spectrum and an ion migration spectrogram.

The following are examples:

example 1

A polyester brush polymer-based polymer electrolyte 1a having a chemical structure of the formula:

the preparation method of the polyester brush-shaped polymer-based electrolyte comprises the following steps:

(1) under the anhydrous and oxygen-free conditions, 624mg of hydroxyethyl methacrylate and 10.9g of epsilon-caprolactone are uniformly mixed to form a monomer mixture;

(2) 6.57mg of azobisisobutyronitrile and 33.48mg of 4-cyano-4- (thiobenzoyl) pentanoic acid were added to the monomer mixture and mixed well;

(3) heating the raw material mixed solution to 60 ℃ in argon atmosphere, reacting for 24 hours to perform reversible addition-fragmentation chain transfer polymerization, and then heating to 130 ℃ to perform ring-opening polymerization for 48 hours. After the reaction is finished, cooling to room temperature, quenching the reaction to obtain a crude product, and dissolving the crude product by adopting tetrahydrofuran to obtain a brush-shaped polymer solution;

(4) adding the brush copolymer solution into anhydrous ether for precipitation, filtering to separate precipitate, and drying to obtain a polyester brush polymer 1 a;

a polyester brush-shaped polymer-based polymer electrolyte is used for preparing an electrolyte membrane of a lithium ion battery, and the preparation method of the electrolyte membrane comprises the following steps:

and dissolving the brush-shaped polymer 1a and the lithium perchlorate in tetrahydrofuran according to the mass ratio of 3:1 to obtain a mixed solution, coating the mixed solution on a porous polyacrylonitrile membrane, and drying to obtain a polymer electrolyte membrane with the thickness of 70 microns to obtain a polymer electrolyte membrane with the thickness of 50 microns.

FIG. 2 shows the NMR spectra of the polyester brush polymer synthesized in this example. FIG. 3 is a kinetic graph of the synthesis of this example. First, reversible addition-fragmentation chain transfer polymerization of hydroxyethyl methacrylate was carried out at 60 ℃ (fig. 3 (a) and fig. 3 (B)). It can be seen that the polymerization of hydroxyethyl methacrylate proceeds rapidly by solvation of epsilon-caprolactone and reaches 99% conversion in 12 hours. ln ([ M)]₀/[M]_t) There is a linear relationship with polymerization time indicating that reversible addition-fragmentation chain transfer polymerization of hydroxyethyl methacrylate is in a controlled state. The molecular weight increased linearly with increasing monomer conversion (FIG. 3, Contents (B)), and a narrower molecular weight distribution was always maintained. It should be noted that the polymerization temperature is not higher than the temperature at which the organic acid catalyzes the hydroxyl group to initiate the ring-opening polymerization of epsilon-caprolactone, which is only used as the solvent for the polymerization of hydroxyethyl methacrylate in the system. As the temperature was increased to 130 deg.C, the polyhydroxyethyl methacrylate initiated the ring-opening polymerization of epsilon-caprolactone catalyzed by the carboxylic acid group in 4-cyano-4- (thiobenzoyl) pentanoic acid (FIG. 4, Contents (C) and FIG. 4, Contents (D)) to 84% conversion in 72 hours. Similarly, the number average molecular weight increases linearly with increasing monomer conversion and, matching the theoretical molecular weight, the molecular weight distribution of the polymer is narrower. The dynamic curve representation proves that the polyester brush-shaped polymer with controllable structure can be synthesized by adopting a one-pot method and regulating and controlling the polymerization reaction temperature and time. From fig. 2 and 3, it can be demonstratedThis example prepares a polyester-based brush polymer 1 a.

Fig. 4 is a graph of the temperature-change conductivity of the polymer electrolyte prepared in this example. FIG. 5 is a graph showing the lithium ion mobility of the polymer electrolyte prepared in this example, from FIG. 4, it can be determined that the lithium ion conductivity of the electrolyte membrane was 4.17X 10 at room temperature^-5S cm^-1. Measuring the transference number (t) of lithium ions of the electrolyte membrane by adopting an alternating current impedance method and a direct current polarization method_Li+). The cell was polarized at 10mV (. DELTA.V) and the initial state (I) was determined₀) And steady state (I)_S) And before polarization (R) is measured₀) And after polarization (R)_S) To obtain the interface resistance, as shown in FIG. 5, by calculating the formula t_Li+＝I_S(ΔV–I₀R₀)/I0(ΔV–I_SR_S) It can be known that the lithium ion transference number of the polymer electrolyte is 0.74.

Example 2

A polyester brush polymer-based polymer electrolyte 1b having a chemical structure of the following formula:

the preparation method of the polyester brush-shaped polymer-based electrolyte comprises the following steps:

(1) under the anhydrous and oxygen-free conditions, 936mg of hydroxyethyl methacrylate and 16.35g of epsilon-caprolactone are uniformly mixed to form a monomer mixture;

(2) adding 9.71mg of dibenzoyl peroxide and 33.48mg of 4-cyano-4- (thiobenzoyl) pentanoic acid to the monomer mixture and mixing well;

(3) heating the raw material mixed solution to 70 ℃ in argon atmosphere, reacting for 20 hours to perform reversible addition-fragmentation chain transfer polymerization, and then heating to 150 ℃ to perform ring-opening polymerization for 16 hours. After the reaction is finished, cooling to room temperature, quenching the reaction to obtain a crude product, and dissolving the crude product by adopting tetrahydrofuran to obtain a brush-shaped polymer solution;

(4) adding the brush copolymer solution into anhydrous ether for precipitation, filtering to separate precipitate, and drying to obtain a polyester brush polymer 1 b;

a polyester brush-shaped polymer-based polymer electrolyte is used for preparing an electrolyte membrane of a lithium ion battery, and the preparation method of the electrolyte membrane comprises the following steps:

dissolving the brush polymer 1b and lithium bis (trifluoromethyl) sulfonyl imide in N-methyl pyrrolidone according to the mass ratio of 4:1 to obtain a mixed solution, coating the mixed solution on a porous polyacrylonitrile membrane, and drying to obtain a polymer electrolyte membrane with the thickness of 100 micrometers.

The polymer had a number average molecular weight of 123800 and a molecular weight distribution of 1.12. The lithium ion conductivity of the electrolyte membrane was 3.7X 10 at room temperature^-5S cm^-1。

Example 3

A polyester brush polymer-based polymer electrolyte 1c having a chemical structure of the formula:

the preparation method of the polyester brush-shaped polymer-based electrolyte comprises the following steps:

(1) under the anhydrous and oxygen-free conditions, 1.25g of hydroxyethyl methacrylate and 19.12g of delta-valerolactone are uniformly mixed to form a monomer mixture;

(2) 9.95mg of azobisisoheptonitrile and 33.48mg of 4-cyano-4- (thiobenzoyl) pentanoic acid were added to the monomer mixture and mixed well;

(3) heating the raw material mixed solution to 50 ℃ in argon atmosphere, reacting for 36 hours to perform reversible addition-fragmentation chain transfer polymerization, and then heating to 140 ℃ to perform ring-opening polymerization for 20 hours. After the reaction is finished, cooling to room temperature, quenching the reaction to obtain a crude product, and dissolving the crude product by adopting tetrahydrofuran to obtain a brush-shaped polymer solution;

(4) adding the brush copolymer solution into anhydrous ether for precipitation, filtering to separate precipitate, and drying to obtain a polyester brush polymer 1 c;

a polyester brush-shaped polymer-based polymer electrolyte is used for preparing an electrolyte membrane of a lithium ion battery, and the preparation method of the electrolyte membrane comprises the following steps:

and dissolving the brush-shaped polymer 1c and lithium hexafluorophosphate in acetonitrile according to the mass ratio of 5:1 to obtain a mixed solution, coating the mixed solution on a porous polyacrylonitrile membrane, and drying to obtain a polymer electrolyte membrane with the thickness of 80 microns.

The polymer had a number average molecular weight of 168100 and a molecular weight distribution of 1.12. The lithium ion conductivity of the electrolyte membrane was 2.6X 10 at room temperature^-5S cm^-1。

Example 4

A polyester brush polymer-based polymer electrolyte 1d having a chemical structure of the following formula:

the preparation method of the polyester brush-shaped polymer-based electrolyte comprises the following steps:

(1) under the anhydrous and oxygen-free conditions, 624mg of hydroxyethyl methacrylate and 5.45g of epsilon-caprolactone are uniformly mixed to form a monomer mixture;

(2) adding 15.97mg of lauroyl peroxide and 33.48mg of 4-cyano-4- (thiobenzoyl) pentanoic acid to the monomer mixture and mixing well;

(3) heating the raw material mixed solution to 60 ℃ in argon atmosphere, reacting for 24 hours to perform reversible addition-fragmentation chain transfer polymerization, and then heating to 130 ℃ to perform ring-opening polymerization for 36 hours. After the reaction is finished, cooling to room temperature, quenching the reaction to obtain a crude product, and dissolving the crude product by adopting tetrahydrofuran to obtain a brush-shaped polymer solution;

(4) adding the brush copolymer solution into anhydrous ether for precipitation, filtering to separate precipitate, and drying to obtain a polyester brush polymer 1 d;

a polyester brush-shaped polymer-based polymer electrolyte is used for preparing an electrolyte membrane of a lithium ion battery, and the preparation method of the electrolyte membrane comprises the following steps:

and dissolving the brush-shaped polymer 1d and lithium perchlorate in tetrahydrofuran according to the mass ratio of 2:1 to obtain a mixed solution, coating the mixed solution on a porous polyacrylonitrile membrane, and drying to obtain a polymer electrolyte membrane with the thickness of 80 microns.

The polymer had a number average molecular weight of 41100 and a molecular weight distribution of 1.13. The lithium ion conductivity of the electrolyte membrane was 3.1X 10 at room temperature^-5S cm^-1。

Example 5

A polyester brush polymer-based polymer electrolyte 1e having a chemical structure of the formula:

the preparation method of the polyester brush-shaped polymer-based electrolyte comprises the following steps:

(1) under the anhydrous and oxygen-free conditions, 624mg of hydroxyethyl methacrylate and 16.35g of epsilon-caprolactone are uniformly mixed to form a monomer mixture;

(2) 6.57mg of azobisisobutyronitrile and 33.48mg of 4-cyano-4- (thiobenzoyl) pentanoic acid were added to the monomer mixture and mixed well;

(3) heating the raw material mixed solution to 60 ℃ in argon atmosphere, reacting for 24 hours to perform reversible addition-fragmentation chain transfer polymerization, and then heating to 120 ℃ to perform ring-opening polymerization for 40 hours. After the reaction is finished, cooling to room temperature, quenching the reaction to obtain a crude product, and dissolving the crude product by adopting tetrahydrofuran to obtain a brush-shaped polymer solution;

(4) adding the brush copolymer solution into anhydrous ether for precipitation, filtering to separate precipitate, and drying to obtain polyester brush polymer 1 e;

a polyester brush-shaped polymer-based polymer electrolyte is used for preparing an electrolyte membrane of a lithium ion battery, and the preparation method of the electrolyte membrane comprises the following steps:

and dissolving the brush-shaped polymer 1e and lithium hexafluorophosphate in dimethyl sulfoxide according to the mass ratio of 2:1 to obtain a mixed solution, coating the mixed solution on a porous polyacrylonitrile membrane, and drying to obtain a polymer electrolyte membrane with the thickness of 60 micrometers.

The number average molecular weight of the polymer was 124000 and the molecular weight distribution was 1.12. The lithium ion conductivity of the electrolyte membrane was 3.5X 10 at room temperature^-5S cm^-1。

Example 6

A polyester brush polymer-based polymer electrolyte 1f having a chemical structure of the formula:

the preparation method of the polyester brush-shaped polymer-based electrolyte comprises the following steps:

(1) under the anhydrous and oxygen-free conditions, 624mg of hydroxyethyl methacrylate, 5.45g of epsilon-caprolactone and 6.88g of DL-lactide are uniformly mixed to form a monomer mixture;

(2) 6.57mg of azobisisobutyronitrile and 33.48mg of 4-cyano-4- (thiobenzoyl) pentanoic acid were added to the monomer mixture and mixed well;

(3) heating the raw material mixed solution to 50 ℃ in argon atmosphere, reacting for 36 hours to perform reversible addition-fragmentation chain transfer polymerization, and then heating to 130 ℃ to perform ring-opening polymerization for 48 hours. After the reaction is finished, cooling to room temperature, quenching the reaction to obtain a crude product, and dissolving the crude product by adopting tetrahydrofuran to obtain a brush-shaped polymer solution;

(4) adding the brush copolymer solution into anhydrous ether for precipitation, filtering to separate precipitate, and drying to obtain a polyester brush polymer 1 f;

a polyester brush-shaped polymer-based polymer electrolyte is used for preparing an electrolyte membrane of a lithium ion battery, and the preparation method of the electrolyte membrane comprises the following steps:

dissolving the brush polymer 1f and lithium bis (trifluoromethyl) sulfonyl imide in N, N-dimethylformamide according to the mass ratio of 7:1 to obtain a mixed solution, coating the mixed solution on a porous polyacrylonitrile membrane, and drying to obtain a polymer electrolyte membrane with the thickness of 90 microns.

The polymer had a number average molecular weight of 94200 and a molecular weight distribution of 1.12. The lithium ion conductivity of the electrolyte membrane was 2.7X 10 at room temperature^-5S cm^-1。

Example 7

1g of a polyester brush polymer-based polymer electrolyte having a chemical structure of the formula:

the preparation method of the polyester brush-shaped polymer-based electrolyte comprises the following steps:

(1) under the anhydrous and oxygen-free conditions, 624mg of hydroxyethyl methacrylate, 5.45g of epsilon-caprolactone and 4.88g of trimethylene carbonate are uniformly mixed to form a monomer mixture;

(2) 9.95mg of azobisisoheptonitrile and 33.48mg of 4-cyano-4- (thiobenzoyl) pentanoic acid were added to the monomer mixture and mixed well;

(3) heating the raw material mixed solution to 80 ℃ in argon atmosphere, reacting for 14 hours to perform reversible addition-fragmentation chain transfer polymerization, and then heating to 150 ℃ to perform ring-opening polymerization for 16 hours. After the reaction is finished, cooling to room temperature, quenching the reaction to obtain a crude product, and dissolving the crude product by adopting tetrahydrofuran to obtain a brush-shaped polymer solution;

(4) adding the brush copolymer solution into anhydrous ether for precipitation, filtering to separate precipitate, and drying to obtain 1g of polyester brush polymer;

a polyester brush-shaped polymer-based polymer electrolyte is used for preparing an electrolyte membrane of a lithium ion battery, and the preparation method of the electrolyte membrane comprises the following steps:

dissolving 1g of the brush polymer and lithium bis (trifluoromethyl) sulfonyl imide in acetonitrile according to the mass ratio of 2:1 to obtain a mixed solution, coating the mixed solution on a porous polyacrylonitrile membrane, and drying to obtain a polymer electrolyte membrane with the thickness of 100 micrometers.

The polymer had a number average molecular weight of 78200 and a molecular weight distribution of 1.11. The electricityThe lithium ion conductivity of the electrolyte membrane was 2.9X 10 at room temperature^-5S cm^-1。

Example 8

A polyester brush polymer-based polymer electrolyte 1h, having a chemical structure of the formula:

the preparation method of the polyester brush-shaped polymer-based electrolyte comprises the following steps:

(1) under the anhydrous and oxygen-free conditions, 624mg of hydroxyethyl methacrylate, 5.45g of epsilon-caprolactone and 4.78g of delta-valerolactone are uniformly mixed to form a monomer mixture;

(2) adding 15.97mg of lauroyl peroxide and 33.48mg of 4-cyano-4- (thiobenzoyl) pentanoic acid to the monomer mixture and mixing well;

(3) heating the raw material mixed solution to 90 ℃ in argon atmosphere, reacting for 12 hours to perform reversible addition-fragmentation chain transfer polymerization, and then heating to 110 ℃ to perform ring-opening polymerization for 48 hours. After the reaction is finished, cooling to room temperature, quenching the reaction to obtain a crude product, and dissolving the crude product by adopting tetrahydrofuran to obtain a brush-shaped polymer solution;

(4) adding the brush copolymer solution into anhydrous ether for precipitation, filtering to separate precipitate, and drying to obtain a polyester brush polymer for 1 h;

a polyester brush-shaped polymer-based polymer electrolyte is used for preparing an electrolyte membrane of a lithium ion battery, and the preparation method of the electrolyte membrane comprises the following steps:

and dissolving the brush-shaped polymer for 1h and the lithium perchlorate in N-methyl pyrrolidone according to the mass ratio of 2:1 to obtain a mixed solution, coating the mixed solution on a porous polyacrylonitrile membrane, and drying to obtain a polymer electrolyte membrane with the thickness of 85 micrometers.

The polymer had a number average molecular weight of 75200 and a molecular weight distribution of 1.12. The lithium ion conductivity of the electrolyte membrane was 3.9X 10 at room temperature^-5S cm^-1。

The synthesis of the polyester brush polymer combines the reversible addition-fragmentation transfer active polymerization reaction in the controllable/'active' free radical polymerization and the ring-opening polymerization reaction of the cyclic ester monomer initiated by hydroxyl catalyzed by organic acid, and realizes the synthesis of the brush polymer from small molecules in one pot. The chain structure of the brush-shaped polymer is adjusted by changing the types of the cyclic lactone monomers, the charging ratio, the temperature, the reaction time and other factors, and the obtained polymer has controllable molecular weight and narrow distribution. The polyester brush polymer obviously reduces the crystallinity of the polyester polymer due to the comb structure, and is beneficial to the migration and movement of lithium ions among side chains. Compared with the prior art, the technical scheme of the invention can better solve the problems that the synthesis of the polyester brush-shaped polymer is complicated, and the molecular weight and the distribution thereof are difficult to regulate and control. The conductive agent is applied to the field of lithium ion batteries, and can effectively improve the conductivity of polyester-based solid polymer electrolytes.

The invention combines a bifunctional chain transfer reagent and a bifunctional monomer hydroxyethyl methacrylate, and utilizes the characteristic that organic carboxylic acid groups in 4-cyano-4- (thiobenzoyl) valeric acid can catalyze hydroxy to initiate ring-opening reaction of cyclic lactone. Compared with the traditional ring-opening polymerization reaction, the adopted organic metal catalyst is greener, and the molecular weight distribution controllability is stronger.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.