Biomass-based graft copolymer EC-g-PVBC as well as preparation method and application thereof

Abstract

The invention relates to the technical field of high polymer materials, and particularly discloses a biomass-based graft copolymer EC-g-PVBC and a preparation method and application thereof, the biomass-based graft copolymer EC-g-PVBC has the following structure: # imgabs0 #, the range of m is 5-500, the range of n is 5-1000, and the R group is H or CH2CH3. The preparation method comprises the following steps: firstly, carrying out micromolecule acylation reaction to obtain an ethyl cellulose macroinitiator, then synthesizing a biomass-based grafted copolymer EC-g-PVBC through atom transfer radical polymerization reaction, and dissolving the copolymer in a low-boiling-point solvent to form a polymer solution; and a high-thickness micro-phase separation orderly-arranged microporous pattern film is obtained through a dropwise addition film forming method. The membrane has potential application value in the fields of water treatment, heavy metal ion removal, battery diaphragms, efficient catalysis, water electrolysis and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly to a biomass-based graft copolymer EC-g-PVBC, a preparation method thereof, and an application thereof. Background Art

[0002] The fuel cell separator is a key component in the battery, which is used to promote ion transport and maintain the battery structure. Its materials are usually prepared from homopolymers, block copolymers, graft copolymers, etc. with good ion transport performance and mechanical stability. The separator materials of early fuel cells had a short lifespan and poor durability in high-temperature environments. And because the molecules of the material itself have a strong polarity, there are some ion exchange groups that affect the conduction of the current, resulting in poor conductivity of the separator. In recent years, the emerging ion-conductive graft copolymer materials form ion-conductive nanochannels through self-assembly induction, which not only improve the conductivity of the materials, but also phase-separate at the nanoscale to form various self-assembled morphologies, such as spheres, hexagonal cylinders, alternating lamellae, etc. Among them, the anion exchange membrane (AEM) can prepare AEM materials with good conductivity and mechanical properties through common methods in the literature. The high selectivity, conductivity, alkali stability and environmental protection characteristics of this material make it a current research and development hotspot in the field of fuel cells.

[0003] However, the challenge in the research of graft copolymer-based AEM materials still lies in solving the problem of maintaining good mechanical properties while improving ion conduction ability. In such AEM materials, the ion transport mainly relies on the adsorption and release of ion exchange groups in the graft copolymer. Anions complete the transport by wriggling through the polymer chain segments in the graft copolymer to cross the voids and energy barriers between the segments. Generally, the preparation cost of graft copolymers is relatively high, and the ion transport efficiency is greatly affected by the membrane structure and water absorption. In 2023, the research group of Gong Chunli reported an anion exchange membrane material based on polymer ionic liquid-filled functionalized bacterial cellulose. Its good conductivity, mechanical properties, and environmental friendliness demonstrated the application prospects of biomass-based anion exchange membrane materials. In addition, the research group of Ulbricht reviewed the development prospects of advanced new membrane materials in membrane science. They pointed out that biomass-based graft copolymer fuel cell diaphragms have become a research hotspot, that is, by means of modification or graft copolymerization to simultaneously achieve the application of biomass-based environmentally friendly materials and improve the ion transport ability, so as to solve the defects of traditional fuel cell diaphragms, such as expensive raw materials, environmental unfriendliness, and low proton transport efficiency, which prevent their practical use. However, for the existing biomass-based graft copolymer membranes, such as the ethyl cellulose-grafted polystyrene sulfonic acid (EC-g-PSSA) ordered microporous thin film (ZL202111348816.X) reported by our research group in 2021, there are only a large number of sulfonic acid groups in the film available for proton transport; and the pore structure of this film is a multi-level ordered microporous thin film structure, with strong proton transport ability. However, this film is negatively charged and can only be used for the transport of cations, not for efficient anion transport. Summary of the Invention

[0004] The object of the present invention is to provide a biomass-based graft copolymer EC-g-PVBC, its preparation method and application. In this project, the biomass-based material ethyl cellulose (EC) is used as the main body of the graft copolymer. On this basis, small molecule acylation reaction and atom transfer radical polymerization (ATRP) reaction are adopted to realize the synthesis of the biomass-based graft copolymer material EC-g-PVBC; finally, a microporous pattern thin film with microphase separation and hexagonal ordered arrangement is prepared by the method of breath figure array self-assembly. The ion channels of the graft copolymer EC-g-PVBC thin film with ordered microstructure, adjustable size, and stable structure have a multi-level ordered microporous structure, enabling it to have stronger ion transport ability and stronger application prospects in the field of fuel cell diaphragm materials.

[0005] In order to achieve the above object, one of the technical solutions of the present invention is: a biomass-based graft copolymer EC-g-PVBC, having the following structure:

[0006]

[0007] Among them, the value range of m is 5 to 500, the value range of n is 5 to 1000, and the R group is CH2CH3 or H.

[0008] In the structure of the biomass-based graft copolymer EC-g-PVBC of the present invention, the value range of m is preferably 20 to 400 or 40 to 200 or 80 to 140, and the value range of n is 10 to 900 or 20 to 300 or 30 to 200.

[0009] In a preferred technical solution, in the graft copolymer, m = 80, n = 900; or m = 80, n = 20; or m = 80, n = 50; or m = 110, n = 10; or m = 110, n = 30; or m = 110, n = 50; or m = 140, n = 30; or m = 140, n = 50; or m = 140, n = 200.

[0010] In another preferred technical solution, in the graft copolymer, m = 80, n = 900.

[0011] Furthermore, in the biomass-based graft copolymer EC-g-PVBC, the number of repeating units m of EC is 5 to 500, and the volume content f of PVBC PVBC is 0.002 to 0.900; preferably, in the biomass-based graft copolymer EC-g-PVBC, the number of repeating units m of EC is 80 to 140, and the volume content f of PVBC PVBC is 0.003 to 0.800.

[0012] The second technical solution of the present invention is: a preparation method of a biomass-based graft copolymer EC-g-PVBC, which specifically includes the following steps:

[0013] (1) Prepare an EC macroinitiator: Using hydroxy-containing ethyl cellulose (hereinafter abbreviated as: hydroxy-containing EC), an acid-binding agent, and an acylating agent as raw materials, after mixing evenly under an ice bath condition, carry out a small molecule acylation reaction at room temperature for 24 to 48 hours to obtain an EC macroinitiator;

[0014] (2) Prepare the biomass-based graft copolymer EC-g-PVBC: Using the above EC macroinitiator, copper chloride, 4-vinylbenzyl chloride (VBC), and a ligand as raw materials, after mixing the EC macroinitiator, VBC, and the ligand evenly in a reaction flask, add a copper chloride catalyst under a nitrogen atmosphere, and finally carry out an atom transfer radical polymerization reaction in an oil bath at 90 to 110 °C for 16 to 48 hours to obtain the biomass-based graft copolymer EC-g-PVBC;

[0015] Furthermore, in step (1), for the hydroxy-containing EC, the ethyl substitution degree is 2.2 - 2.5, and its structural formula is:

[0016]

[0017] Preferably, the acid-binding agent in step (1) is selected from one or a mixture of several of anhydrous 4-dimethylaminopyridine, anhydrous triethylamine, anhydrous N,N-diisopropylethylamine, and anhydrous pyridine. The best choice is anhydrous 4-dimethylaminopyridine;

[0018] The acylating agent in step (1) is selected from one or a mixture of several of 2-bromo-2-methylpropanoyl bromide, 2-bromo-2-methylpropanoyl chloride, 2-fluoro-2-methylpropanoyl bromide, and 2-chloro-2-methylpropanoyl bromide. The best choice is 2-bromo-2-methylpropanoyl bromide:

[0019] The ligand in step (2) is selected from one or a mixture of several of pentamethyldiethylenetriamine, N,N'-dimethylethylenediamine, tetraethylenepentamine, and pentamethyldipropylenetriamine. The best choice is pentamethyldiethylenetriamine;

[0020] Furthermore, step (1) is carried out in a solvent, and the solvent is selected from one or a mixture of several of anhydrous tetrahydrofuran, anhydrous chloroform, anhydrous toluene, and anhydrous dichloromethane. The best choice is anhydrous tetrahydrofuran;

[0021] Furthermore, step (2) is carried out in a solvent, and the solvent is selected from one or a mixture of several of anhydrous chlorobenzene, N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone. It is preferably a mixture of one or two of N,N-dimethylformamide and anhydrous chlorobenzene. The best choice is anhydrous chlorobenzene; The best solvent for synthesizing the graft copolymer EC-g-PVBC in the present invention is anhydrous chlorobenzene because the 4-vinylbenzyl chloride (VBC) monomer is miscible with chlorobenzene by the principle of like dissolves like, and the ligand and the EC macroinitiator can also dissolve well in chlorobenzene at room temperature, making the reaction conditions in this ATRP polymerization mild and easy to control, and the reaction rate is relatively fast. In addition, the EC macroinitiator still maintains a high activity in the ATRP reaction system, and the radical polymerization initiated by it can obtain an EC-g-PVBC graft copolymer with a very narrow molecular weight distribution.

[0022] The best molar ratio between the reactants in step (1) is: hydroxy-containing EC: acylating agent: acid-binding agent = 1:(3 - 500):(3 - 500).

[0023] The best molar ratio between the reactants in step (2) is: EC macroinitiator: ligand: copper(I) chloride: 4-vinylbenzyl chloride = 1:2:2:(40 - 2000).

[0024] In step (1), the reaction time of the system is controlled within 24 to 48 h, and the optimal reaction time is 24 h; in step (2), the reaction time of the system is controlled within 16 to 48 h, and the optimal reaction time is 24 h.

[0025] As a preferred method for preparing the biomass-based graft copolymer EC-g-PSSA of the present invention, the raw materials used in step (1) are hydroxyl-containing EC, 2-bromoisobutyryl bromide, and anhydrous 4-dimethylaminopyridine, and the raw materials used in step (2) are EC macroinitiator, pentamethyldiethylenetriamine, 4-vinylbenzyl chloride, and copper chloride.

[0026] Furthermore, the preparation method of the present invention specifically includes the following steps:

[0027] (1) Synthesis of EC macroinitiator: Weigh a certain amount of hydroxyl-containing ethyl cellulose (EC), solvent, and acid-binding agent and add them to a three-necked flask, and stir in an ice bath at 0-8 °C; after the solution is mixed evenly, measure a certain amount of solvent and acylating reagent, mix them and load them into a constant-pressure dropping funnel, and slowly drop them into the above system; after dropping, remove the ice bath pot and allow the system to react at room temperature for 24 to 48 h to obtain a crude product.

[0028] (2) Synthesis of EC-g-PVBC graft copolymer: Add the EC macroinitiator, ligand, solvent, and 4-vinylbenzyl chloride monomer to a Schlenk eggplant-shaped flask, freeze the mixed solution with liquid nitrogen, and add copper chloride (CuCl) under a nitrogen atmosphere; evacuate under liquid nitrogen freezing for 3 to 5 min, then thaw and stir for 3 to 5 min under nitrogen gas passing, repeat the process of evacuation and thawing 3 to 5 times, and finally react in an oil bath at 110 °C under vacuum for 16 to 24 h to obtain a crude product.

[0029] To ensure the purity of the obtained crude product, there are subsequent post-treatment operations for the crude products obtained in the above steps (1) and (2):

[0030] For the operation after the reaction in step (1), that is: slowly pour the reaction solution into an excessive amount of deionized water for washing, repeat the sedimentation and washing with deionized water multiple times, and then vacuum dry at 40 °C to obtain a crude product.

[0031] For the operation after the reaction in step (2), that is: quickly quench the reaction with liquid nitrogen after taking it out from the oil bath pot, dissolve the reaction solution with dichloromethane, pass it through a neutral alumina column to remove copper salts, wash the product with an ether or alcohol solvent, and then vacuum dry at 40 °C to obtain a crude product.

[0032] Among them, the ether solvent used above is cold petroleum ether, ethyl ether or a mixed solution of the two; preferably, cold petroleum ether solvent is used to wash and settle the reaction product; the alcohol solvent used above is methanol, ethanol, or propanol, and preferably, methanol solvent is used for further washing and settling;

[0033] The present invention also provides a biomass-based graft copolymer EC-g-PVBC prepared by any one of the above methods.

[0034] The biomass-based graft copolymer EC-g-PVBC synthesized in the present invention is polymerized by two-step reactions, namely small molecule acylation reaction and atom transfer radical polymerization reaction, and finally the biomass-based graft copolymer EC-g-PVBC is prepared by polymerization.

[0035] The third technical solution of the present invention is: a microporous pattern film with microphase separation and ordered arrangement of a biomass-based graft copolymer EC-g-PVBC, and the film is prepared from the biomass-based graft copolymer EC-g-PVBC. Preferably, after the biomass-based graft copolymer EC-g-PVBC is prepared into a film and then quaternized, a fuel cell separator with microphase separation and ordered arrangement of the biomass-based graft copolymer EC-g-PVBC is obtained.

[0036] Furthermore, the macropores on the surface of the microporous pattern film are arranged in a hexagonal order, and the secondary small holes are arranged disorderly in the framework of the film.

[0037] Furthermore, the pore diameter of the macropores in the microporous pattern film is from several hundred nanometers to several micrometers, and the pore diameter of the secondary small holes is from several nanometers to several hundred nanometers.

[0038] For the structure of the microporous pattern film with microphase separation and ordered arrangement of the biomass-based graft copolymer EC-g-PVBC of the present invention, where the macropores on the surface are arranged in a hexagonal order and the secondary small holes are arranged disorderly on the framework, the pore diameters and spacings of the above macropores and small holes can be adjusted by changing the numerical value of different repeating units of EC within the range of PVBC volume content f PVBC to obtain a hexagonal ordered microporous film with an ideal pore diameter.

[0039] The fourth technical solution of the present invention is: a preparation method of a microporous pattern film with microphase separation and ordered arrangement of a biomass-based graft copolymer EC-g-PVBC. The specific operation steps are as follows: A solution with a certain concentration is prepared by mixing the biomass-based graft copolymer EC-g-PVBC and a solvent, and the solution is slowly dropped onto a support to form a film by self-assembly of a breath figure array, and then naturally dried in an environment with a certain humidity to obtain a porous film.

[0040] Furthermore, the support is selected from one of polyethylene terephthalate, tin foil, glass sheet, silicon wafer, and aluminum foil;

[0041] Further, the solvent is selected from one or a mixture of chloroform, dichloromethane, trichloromethane, tetrahydrofuran, carbon disulfide, etc., and a biomass-based graft copolymer EC-g-PVBC with a solution concentration of 2 mg / mL to 12 mg / mL is prepared.

[0042] Further, the environmental humidity is 20% to 90%, and the natural air-drying time of the solution dropped on the support is 1 to 24 h; the best choice is to naturally air-dry the solvent for 16 to 24 h in an environment with a humidity of 50% to 90%.

[0043] The fifth aspect of the technical solution of the present invention is that the microporous pattern film with microphase separation and ordered arrangement of any of the above biomass-based graft copolymers EC-g-PVBC or the microporous pattern film with microphase separation and ordered arrangement of the biomass-based graft copolymer EC-g-PVBC prepared by any of the above methods has potential applications in the fields of water treatment, ion separation, water electrolysis, high-efficiency catalysis, fuel cell membranes, etc.; preferably in the application of fuel cell membranes; more preferably in the application of fuel cell membranes after quaternization of benzyl chloride with triethylamine, and mild conditions are selected for the quaternization process to be conducive to maintaining the morphology of the membrane.

[0044] In the biomass-based graft copolymer of the present invention, one graft segment is a biomass-based ethyl cellulose (EC) ring structure, which has good stability and mechanical properties, improves the ion exchange capacity and selectivity of the graft copolymer, and has the advantages of low price and environmental protection; the other graft chain segment is poly(4-vinylbenzyl chloride) (PVBC), which has properties such as high chemical stability and thermal stability, and rich functionalization possibilities; the Huggins parameter value of the interaction between the two graft chain segments in the biomass-based graft copolymer EC-g-PVBC is relatively large, and it contains a structurally stable and microphase-separated cyclic EC chain segment, as well as a PVBC chain segment that can introduce different functional groups through chemical modification or grafting reactions, and can realize the preparation of a porous pattern film with stable structure, high ion exchange capacity, and easy regulation, providing potential copolymer materials for the preparation of fuel cell membrane materials, ion separation materials, water electrolysis membrane materials, high-efficiency catalytic materials, etc.

[0045] "EC-g-PVBC", "EC-g-PVBC graft copolymer", "biomass-based EC-g-PVBC graft copolymer", and "biomass-based graft copolymer EC-g-PVBC" involved in the present invention have the same meaning.

[0046] The raw materials or reagents involved in the present invention can all be obtained commercially.

[0047] On the basis of conforming to the common knowledge in the art, the above preferred conditions can be combined with each other to obtain the preferred embodiments of the present invention. Brief Description of the Drawings

[0048] Figure 1 is the prepared EC 80 -Br macroinitiator's 1 H NMR spectrum;

[0049] Figure 2 is the synthesized EC 80 -g-PVBC 900 graft copolymer's 1 H NMR spectrum;

[0050] Figure 3 is the raw material EC 140 、synthesized EC 140 -Br macroinitiator and EC 140 -g-PVBC 200 graft copolymer's FTIR spectrum;

[0051] Figure 4 is the EC 80 -g-PVBC 900 SEM image of the upper surface of the microporous pattern film with microphase-separated ordered arrangement;

[0052] Figure 5 is the EC 140 -g-PVBC 200 SEM cross-sectional image of the microporous pattern film with microphase-separated ordered arrangement. Specific embodiments

[0053] The following examples are used to illustrate the present invention, but are not used to limit the scope claimed in the claims of the present invention. Operations involved in the following examples are all conventional operations in the art without special instructions.

[0054] Example 1

[0055] Preparation method of biomass-based graft copolymer EC 80 -g-PVBC 900 Specifically includes the following steps:

[0056] (1) Synthesis of EC 80 -Br macroinitiator:

[0057] Add 6.72 g of hydroxy-containing ethyl cellulose powder (hydroxy-containing EC 80)(Viscosity: 18 - 22 mPa·s) and 0.14 g of 4-dimethylaminopyridine (DMAP), and then use a graduated cylinder to measure 50 mL of anhydrous tetrahydrofuran (THF) and pour it into a three-necked flask; place the above flask in an ice bath at 0 °C and use an electric stirrer to stir to fully dissolve EC and DMAP in the solvent THF to form a transparent solution; then use a syringe to suck 0.27 g of 2-bromoisobutyryl bromide, add 10 mL of THF for mixing and dilution, then add it to a 25 mL constant pressure funnel, turn the stopper of the constant pressure funnel to adjust the flow rate of the mixed liquid and add it dropwise to the reaction system and continuously add ice cubes to control the temperature of the ice bath; after the mixed liquid is added dropwise, remove the constant pressure dropping funnel and plug it with a cork, remove the ice bath and let the system continue to react at room temperature for 24 h. The molar ratio of each raw material and reagent is that the hydroxyl-containing EC 80 powder: DMAP: 2-bromoisobutyryl bromide = 1:3:3.

[0058] After the above acylation reaction is completed, slowly pour the reaction solution into an excessive amount of deionized water for washing, repeat the sedimentation and washing with deionized water for multiple times and then vacuum dry at 40 °C to obtain EC 80 -Br macroinitiator;

[0059] Its 1 1H NMR spectrum is shown in Figure 1 , and the FTIR spectrum is shown in Figure 3 .

[0060] (2) Synthesis of EC 80 -g-PVBC 900 graft copolymer:

[0061] Add 0.5 g of EC 80 -Br macroinitiator to a washed and dried Schlenk flask, use a clean dropper to suck 6 mL of dehydrated chlorobenzene, and stir magnetically to fully dissolve the EC-Br macroinitiator in chlorobenzene. Then use a pipette to suck 12 μL of the ligand pentamethyldiethylenetriamine (PMDETA) and add it to the Schlenk flask and stir evenly. Then add 3 mL of VBC to the above Schlenk flask and stir evenly. Then, place the Schlenk flask in liquid nitrogen for freezing until the mixed solution freezes. After the mixed solution freezes, evacuate for a few minutes, and finally introduce nitrogen and add 5.7 mg of copper chloride (CuCl) catalyst under a nitrogen atmosphere, and then seal the upper mouth of the bottle with a rubber stopper. The molar ratio of each reagent added is that of EC 80-Br macromolecular initiator: VBC: ligand: CuCl = 1:1000:2:2. After thawing, stir the solution thoroughly, then evacuate for 3 min under liquid nitrogen freezing, thaw and stir for about 3 min under nitrogen purging, and repeat this operation 3 times; finally, freeze the mixed solution with liquid nitrogen and evacuate, tighten the high-vacuum stopcock knob of the Schlenk flask, and place it in an oil bath at 110 °C with magnetic stirring for reaction for 24 h.

[0062] After the reaction is completed, take out the Schlenk flask from the oil bath and quickly quench the reaction system with liquid nitrogen. Remove the rubber stopper at the bottle mouth, dissolve the obtained crude product with dichloromethane, and pass it through a neutral alumina column to remove copper salts. Slowly drip the filtrate after removing copper salts with a dropper into cold petroleum ether with magnetic stirring for precipitation, and repeat this operation three times to remove unreacted monomers and oligomers. After the precipitation is completed, place the solution in a centrifuge for high-speed centrifugation to separate the solid and liquid. Dissolve the separated solid with a small amount of dichloromethane, suck it with a dropper and slowly drip it into methanol with magnetic stirring for precipitation, repeat this operation three times, and finally centrifuge and separate to obtain the solid, which is vacuum dried at 40 °C to obtain 0.6 g of pure white powder, namely EC 80 -g-PVBC 900 Graft copolymer, its 1 The 1H NMR spectrum is shown in Figure 2 .

[0063] Example 2

[0064] EC 140 -g-PVBC 200 The preparation method of the graft copolymer is the same as that in Example 1, and the difference is only that:

[0065] In step 1), hydroxy-containing ethyl cellulose powder (hydroxy-containing EC 140 ) with a viscosity of 90 - 110 mPa·s, 4-dimethylaminopyridine (DMAP), and 2-bromoisobutyryl bromide are used as raw materials, and the amounts used are 12.0 g, 0.14 g, and 0.27 g respectively. The molar ratio of each raw material to the reagent is hydroxy-containing EC 140 powder: DMAP: 2-bromoisobutyryl bromide = 1:3:3. Finally, 10.5 g of EC 140 -Br macromolecular initiator is obtained;

[0066] In step 2), the molar ratio of EC 140 -Br macromolecular initiator: VBC: ligand: catalyst = 1:40:2:2. The amounts of each substance used are: EC 140 -Br macromolecular initiator 0.5 g, ligand 12 μL, CuCl 5.6 mg, VBC 0.4 g, and the reaction solvent anhydrous chlorobenzene 6.0 mL. Finally, EC with 200 PVBC chain segments is obtained140 -g-PVBC 200 0.5 g of graft copolymer;

[0067] The product EC is obtained 140 -g-PVBC 200 The FTIR spectrum of Figure 3 .

[0068] Example 3

[0069] This example provides a method for preparing a microporous pattern film of a graft copolymer EC-g-PVBC with a microphase-separated hexagonal ordered arrangement. The specific operation steps are as follows:

[0070] (1) Prepare an EC 80 -g-PVBC 900 copolymer solution: Take 2 mg of the graft copolymer EC prepared in Example 1 80 -g-PVBC 900 and dissolve it in 1 mL of chloroform. Stir well at room temperature to make it evenly mixed, and then a graft copolymer / CHCl3 solution with a concentration of 2 mg / mL is obtained. Take a 2 cm * 2 cm silicon wafer, first ultrasonically clean it in acetone for 0.5 h, and then ultrasonically clean it in ethanol for 0.5 h. Take out the silicon wafer with clean tweezers and purge it with nitrogen until the surface of the silicon wafer is dry for use. Use a clean dropper to suck 1 mL of the 2 mg / mL EC 80 -g-PVBC 900 copolymer / CHCl3 solution and drop it onto the clean silicon wafer. Wait for the breath figure array to self-assemble into a film, and naturally air-dry the solution for 24 h under 60% humidity conditions. Finally, a porous film with a thickness of 1 μm can be obtained.

[0071] The scanning electron microscopy image of the upper surface of this film is shown in Figure 4 , and the macropores in this film are arranged in a hexagonal ordered pattern with a size of 3 μm.

[0072] Example 4

[0073] This example provides a method for preparing a microporous pattern film with a microphase-separated ordered arrangement of a biomass-based graft copolymer EC 140 -g-PVBC 200 . The preparation method is the same as that in Example 3, with the only difference being that the graft polymer raw material used is the EC 140 -g-PVBC 200 prepared in Example 2, and the concentration of the prepared solution is 4 mg / mL. The cross-sectional scanning electron microscopy image of this film is shown in Figure 5 .

[0074] Sample preparation for cross-sectional scanning electron microscopy of the film: Quench the film in liquid nitrogen, take it out after a few seconds, cut it with a glass knife, and then sputter it with gold to obtain a cross-sectional electron microscopy sample of the film for electron microscopy detection.

[0075] Although the present invention has been described in detail above with general descriptions, specific embodiments and experiments, modifications or improvements can be made to it based on the present invention, which will be obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of the present invention claimed.

Claims

1. A microporous pattern film with an ordered arrangement of microphase separation of a biomass-based graft copolymer EC-g-PVBC, characterized in that, The thin film is prepared by self-assembly of the biomass-based graft copolymer EC-g-PVBC through a breath figure array. Specifically, a solution of the biomass-based graft copolymer EC-g-PVBC with a concentration of 2 mg / mL to 12 mg / mL is prepared using one or a mixture of chloroform, dichloromethane, trichloromethane, tetrahydrofuran, and carbon disulfide as solvents. Then, it is slowly dropped onto a support and naturally air-dried for 1 to 24 h in an environment with a humidity of 20% to 90% to obtain the thin film. The macropores on the surface of the microporous pattern thin film are arranged in a hexagonal order, and the secondary micropores are arranged disorderly in the framework of the thin film. The pore diameter of the macropores is from several hundred nanometers to several micrometers, and the pore diameter of the secondary micropores is from several nanometers to several hundred nanometers. The structure of the biomass-based graft copolymer EC-g-PVBC is as follows: Among them, m is 5 to 500, n is 5 to 1000, R is H or CH2CH3, the degree of ethyl substitution is 2.2 to 2.5, and the volume content f of PVBC in the biomass-based graft copolymer EC-g-PVBC PVBC is 0.002 to 0.

900.

2. A microporous pattern thin film with microphase separation and ordered arrangement of the biomass-based graft copolymer EC-g-PVBC according to claim 1, wherein The support is selected from one of polyethylene terephthalate, tin foil, glass sheet, silicon wafer, and aluminum foil; and / or: Preferably, the solvent is naturally air-dried for 16 to 24 h in an environment with a humidity of 50% to 90%.

3. The microporous pattern film with ordered microphase separation of the biomass-based graft copolymer EC-g-PVBC according to claim 1, characterized in that, The m is 20 to 400 or 40 to 200 or 80 to 140, and the n is 10 to 900 or 20 to 300 or 30 to 200.

4. A microporous pattern film with ordered microphase separation of a biomass-based graft copolymer EC-g-PVBC as described in claim 1, characterized in that, where m is 80 - 140, and the volume content f of PVBC in the biomass-based graft copolymer EC-g-PVBC PVBC is 0.003 - 0.

800.

5. A microporous pattern film with ordered microphase separation of a biomass-based graft copolymer EC-g-PVBC as described in claim 1, characterized in that, The m = 80, n = 900; or m = 80, n = 20; or m = 80, n = 50; or m = 110, n = 10; or m = 110, n = 30; or m = 110, n = 50; or m = 140, n = 30; or m = 140, n = 50; or m = 140, n = 200.

6. A microporous pattern film with an ordered arrangement of microphase separation of a biomass-based graft copolymer EC-g-PVBC, according to any one of claims 1-5, characterized in that, The preparation method of the biomass-based graft copolymer EC-g-PVBC specifically includes the following steps: (1) Preparation of the EC macroinitiator: Using hydroxyethyl cellulose, an acid-binding agent, and an acylating agent as raw materials, after mixing evenly under ice bath conditions, a small molecule acylation reaction is carried out at room temperature for 24 to 48 h to obtain the EC macroinitiator. (2) Preparation of the biomass-based graft copolymer EC-g-PVBC: Using the above EC macroinitiator, copper chloride, 4-vinylbenzyl chloride, and a ligand as raw materials, after mixing the EC macroinitiator, 4-vinylbenzyl chloride, and the ligand evenly in a reaction flask, a copper chloride catalyst is added under a nitrogen atmosphere, and an atom transfer radical polymerization reaction is carried out in an oil bath at 90 to 110 °C for 16 to 48 h to obtain the biomass-based graft copolymer EC-g-PVBC.

7. A microporous pattern film with an ordered arrangement of microphase separation of a biomass-based graft copolymer EC-g-PVBC according to claim 6, characterized in that, In step (1), the acid-binding agent is selected from one or a mixture of anhydrous 4-dimethylaminopyridine, anhydrous triethylamine, anhydrous N,N-diisopropylethylamine, and anhydrous pyridine; and / or: The acylating agent is selected from one or a mixture of 2-bromo-2-methylpropionyl bromide, 2-bromo-2-methylpropionyl chloride, 2-fluoro-2-methylpropionyl bromide, and 2-chloro-2-methylpropionyl bromide; and / or: In step (2), the ligand is selected from one or a mixture of pentamethyldiethylenetriamine, N,N′-dimethylethylenediamine, tetraethylenepentamine, and pentamethyldipropylenetriamine; and / or: Step (1) is carried out in a solvent selected from one or a mixture of several of anhydrous tetrahydrofuran, anhydrous chloroform, anhydrous toluene, and anhydrous dichloromethane; and / or: Step (2) is carried out in a solvent selected from one or a mixture of several of anhydrous chlorobenzene, N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.

8. A microporous pattern film with an ordered arrangement of microphase separation of a biomass-based graft copolymer EC-g-PVBC according to claim 6, characterized in that, The acid-binding agent in step (1) is 4-dimethylaminopyridine; and / or: The acylating agent is 2-bromo-2-methylpropanoyl bromide; and / or: The ligand in step (2) is pentamethyldiethylenetriamine; and / or: Step (1) is carried out in a solvent, and the solvent is anhydrous tetrahydrofuran; and / or: Step (2) is carried out in a solvent, and the solvent is N,N-dimethylformamide and / or anhydrous chlorobenzene.

9. A microporous pattern film with an ordered arrangement of microphase separation of a biomass-based graft copolymer EC-g-PVBC according to claim 6, characterized in that, In step (1), the molar ratio of hydroxyethyl cellulose containing a hydroxyl group: acylating agent: acid-binding agent in the reactants = 1:(3 - 500):(3 - 500); and / or: In step (2), the molar ratio of EC macroinitiator: ligand: copper(I) chloride: 4-vinylbenzyl chloride in the reactants = 1:2:2:(40 - 2000).

10. Application of the microporous pattern film with microphase separation and ordered arrangement of the biomass-based graft copolymer EC-g-PVBC according to any one of claims 1 to 9 in the fields of water treatment, heavy metal ion removal, water electrolysis, efficient catalysis, and fuel cell membranes; preferably in fuel cell membranes; more preferably in fuel cell membranes after quaternization of benzyl chloride with triethylamine.

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