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CN-121975075-A - Fluorine-free polyphenylene pyridine anion exchange membrane and preparation method thereof

CN121975075ACN 121975075 ACN121975075 ACN 121975075ACN-121975075-A

Abstract

The invention belongs to the technical field of anion exchange membranes, and particularly discloses a fluoride-free polyalkylene pyridine anion exchange membrane and a preparation method thereof, wherein the anion exchange membrane is prepared from a polymer formed by three structural units of one of pyridine side chain structural units shown in optional formulas 1A, 1B and 1C and one of aromatic structural units shown in optional formulas 2A, 3B and 3C, and the fluoride-free polyalkylene pyridine anion exchange polymer comprises a hydrophobic main chain structure and a hydrophilic pyridine side chain structure, and quaternization is performed on tertiary amine or nitrogen-containing heterocyclic structure of a main chain precursor, so that the formed anion exchange membrane not only shows better alkali stability, but also shows higher conductivity and good phase separation excellent performances of a poly (aryl-alkylene) pyridinium salt polymer.

Inventors

  • Xu Shaodie
  • Qiao Shujia
  • LIN GUANSHENG
  • LIN SHENGXIN

Assignees

  • 佛山大学
  • 安极能源(广东)有限公司

Dates

Publication Date
20260505
Application Date
20260116

Claims (8)

  1. 1. A fluoride-free polyalkylene pyridine anion exchange membrane is characterized in that the anion exchange membrane raw material is prepared from a polymer formed by three structural units of one of pyridine side chain structural units shown in optional formulas 1A, 1B and 1C, and one of aromatic structural units shown in formula 2A and cationic group structural units shown in optional formulas 3A, 3B and 3C: ; each R 1 、R 2 、R 3 、R 4 、R 5 is independently selected from hydrogen or alkyl, aryl, alkenyl, and alkynyl; Each R 6 、R 7 、R 8 、R 9 、R 10 is independently alkyl; R 11 is absent when the dotted line is absent, R 11 is alkyl, alkenyl, alkynyl when the dotted line is present, and the alkyl, alkenyl, alkynyl is optionally substituted with a non-fluorine halide; Each of R 12 、R 13 、R 14 、R 15 、R 16 、R 17 、R 18 and R 19 is independently any one of hydrogen, a non-fluoro halide, an alkyl, alkenyl, alkynyl, aryl, and the alkyl, alkenyl, alkynyl, or aryl is optionally substituted with a non-fluoro halide, and wherein R 12 and R 16 are optionally attached to a non-fluoro halide or an alkyl substituted five-or six-membered ring; is one of Br - 、I - 、Cl - 、OH - 、HCO 3 - .
  2. 2. A method for preparing a fluorine-free polyphenylene pyridine anion exchange membrane according to claim 1, comprising the steps of: S1, dissolving a structural monomer of a formula 3A or 3B or 3C, a structural monomer of a formula 1A or 1B or 1C pyridine side chain and an aromatic monomer formula 2A in an organic solvent, cooling to 0 ℃ by using an ice bath, dropwise adding a catalyst, polymerizing 2 h-12 d under the condition of 0 ℃, adding a polar solvent into a reaction solution after the reaction is finished to quench the reaction, dissolving a polymer under the condition of 100 ℃, pouring the dissolved mixed solution into a precipitation solvent, precipitating a white solid, filtering under reduced pressure, drying in vacuum after deionized water to obtain a white solid first intermediate polymer; S2, dissolving the prepared white solid first intermediate polymer with a polar solvent, carrying out alkylation reaction with an alkylating reagent at room temperature to react more than 12 h, precipitating and filtering with the solvent to obtain a pale yellow solid, heating, refluxing and washing in a strong alkaline solution to remove pyridinium salt and retain quaternary ammonium salt groups with strong alkali resistance, washing with distilled water, and filtering to obtain a pale yellow powdery polymer; s3, vacuum drying the light yellow powdery polymer, dissolving the polymer in a polar solvent, centrifuging, casting the polymer on a substrate, drying the polymer to form a film, and drying the film under vacuum to obtain the anion exchange membrane.
  3. 3. The method for preparing a fluorine-free polyphenylene pyridine anion exchange membrane according to claim 1, wherein the organic solvent is one or more of dichloromethane, dichloroethane, trifluoroacetic acid, trifluoromethanesulfonic acid, chloroform, 1, 2, 2-tetrachloroethane and dimethylacetamide.
  4. 4. The method for preparing a fluorine-free polyphenylene pyridine anion exchange membrane according to claim 1, wherein the catalyst is one or more of trifluoromethanesulfonic acid, pentafluoroethanesulfonic acid, heptafluoro-1-propanesulfonic acid, trifluoroacetic acid, perfluoropropionic acid and heptafluorobutyric acid.
  5. 5. The method for preparing a fluorine-free polyphenylene pyridine anion exchange membrane according to claim 1, wherein the precipitation solvent is one or more of water, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol and tetrahydrofuran.
  6. 6. The method for preparing a fluorine-free polyphenylene pyridine anion exchange membrane according to claim 1, wherein the polar solvent is one or more of ethyl acetate, propyl acetate, n-butyl acetate and isobutyl acetate.
  7. 7. The method for preparing a fluorine-free polyphenylene pyridine based anion exchange membrane according to claim 2, wherein the alkylating agent is one or more of methyl iodide, ethyl iodide, 1-iodopropane, 1-iodobutane, 1-iodopentane, 1-iodohexane, 1, 10-dibromodecane, bromomethane, bromoethane, 1-bromopropane, 1-bromobutane, 1-bromopentane, 1-bromohexane, chloromethane, chloroethane, 1-chloropropane, 1-chlorobutane, 1-chloropentane, 1-chlorohexane, 1, 3-dibromopropane, 1, 4-dibromobutane, 1, 5-dibromopentane, 1, 6-dibromohexane, 1, 7-dibromoheptane, 1, 3-diiodopropane, 1, 4-diiodobutane, 1, 5-diiodopentane, 1, 6-diiodohexane, 1, 7-diiodoheptane, trifluoromethanesulfonate, methanesulfonate, fluorosulfonate methyl ester, 1, 2-dimethylphosphate, and trimethylphosphate trap.
  8. 8. The method for producing a fluorine-free polyphenylene pyridine anion exchange membrane according to claim 1, wherein the base material is one of a stainless steel plate, a glass plate, a PET plate, a polypropylene plate, and a polyester film.

Description

Fluorine-free polyphenylene pyridine anion exchange membrane and preparation method thereof Technical Field The invention relates to the technical field of anion exchange membranes, in particular to a fluoride-free polyphenylene pyridine anion exchange membrane and a preparation method thereof. Background With the efficient development of hydrogen energy technology, a method for preparing high-purity hydrogen by using low-temperature water electrolysis technology has attracted attention from chemists, wherein an Anion Exchange Membrane (AEM) electrolyzer composed of an anion exchange membrane and a catalytic electrode has the characteristics of being capable of using a low or non-platinum-based metal (PGM) electrocatalyst and generating pressurized hydrogen in an alkaline environment, so that the problem of high cost caused by expensive materials in the proton exchange membrane water electrolysis technology is solved, and the method is a serious problem in current research. Ion conductivity is one of the core parameters of an AEM membrane, and the ion conductivity determines the efficiency of OH-conduction in the (AEM) electrolytic cell, and low conductivity often results in large dissipation loss in energy conversion application, which affects the working efficiency of the device. However, the efficiency of OH-conduction in basic anion exchange membranes is far lower than the conduction efficiency of h+ in its acidic counterpart, which greatly limits the development of (AEM) cells. At present, the main means for improving the OH-conductivity is to introduce hydrophobic chains, mainly perfluoro and polyfluoroalkyl chains, into the main chain of an anion exchange polymer (APE) to improve the hydrophilic/hydrophobic microphase separation of the APE, drive ion clusters on the APE to form larger ion channels, and improve the OH-mobility. Compared with the conventional method for increasing the IEC value of the anion exchange membrane, the method has the advantages that the conductivity is improved, the membrane is ensured to have lower water absorption/swelling rate, the service life of the device is prolonged, and the method is the key point of the research. Currently, the polyphenylene APE has higher application potential due to alkali resistance, high conductivity and better mechanical strength, and is the main stream direction of the current APE polymer research. Most patent protection or literature reports that a small amount of fluorine-containing groups are added into the polymer, the fluorine-containing groups can adjust the hydrophilicity and hydrophobicity of a polymer chain and improve microphase separation effect, and swelling can be effectively reduced and conductivity can be increased. Chinese patent CN119275318a discloses a fluorinated poly (aryl piperidine) anion exchange membrane containing flexible biphenyl. Wherein the molar ratio of the piperidine cation to the fluorinated group in the polymer backbone is 9:1 and the molar ratio of flexible biphenyl to terphenyl is 1 (3,4,9,17) or (0:1). The introduction of flexible biphenyl containing foldable and rotatable flexible alkyl chain promotes the aggregation of piperidine cationic groups, and constructs a more obvious hydrophilic/hydrophobic microphase separation structure with fluorinated groups, thereby effectively improving the conductivity of the membrane. At the same time, the hydrophobic fluorinated groups and the highly rigid aryl rings maintain excellent mechanical properties and dimensional stability. The experimental result shows that the anion conductivity of the anion exchange membrane is 90.37-151.02 mS/cm at 80 ℃, and the thickness of the anion exchange membrane is 23-26 mu m. However, perfluoro and polyfluoroalkyl substances (PFAS) have extremely strong environmental persistence, can accumulate in the human body through bioaccumulation effects, significantly increase health risks such as carcinogenesis, immune system disorder, etc., and for this hazard, the european chemical administration (ECHA) issued perfluoro and polyfluoroalkyl substances (PFAS) restriction proposals, abbreviated as fluorine bans. Fluoropolymers are one of the subsets of PFAS and are also the subject of focus on fluorine exclusion, all of which are encompassed by proposed fluorine exclusion. At the same time, the fluorochemical raw materials tend to be relatively expensive, which makes the corresponding membranes relatively expensive to manufacture, which greatly affects the commercial development of (AEM) cells. Therefore, it is urgent to find a fluorine-free alternative anionic polymer. Research shows that the introduction of a hydrophilic side chain containing oxygen or nitrogen into an APE side chain is also beneficial to forming a hydrophilic/hydrophobic phase separation structure in the membrane, and the oxygen or nitrogen in the hydrophilic side chain can form a hydrogen bond with water or hydrated OH-ions, so that the transmission channel of the OH-ion