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CN-122011383-A - Polymer, chlorine-containing polyimide gas separation composite membrane, and preparation method and application thereof

CN122011383ACN 122011383 ACN122011383 ACN 122011383ACN-122011383-A

Abstract

The application discloses a polymer, a polyimide gas separation composite membrane containing chlorine, and a preparation method and application thereof. The structural unit of the polymer is shown as a formula I: Is soluble in weak aprotic solvents (such as acetone and toluene) and provides convenient conditions for secondary processing. The polyimide is used as a coating material, and a weak aprotic solvent is selected so as not to dissolve the base film. Solves the difficulty that polyimide gas separation membranes can only be prepared by a phase inversion method at present. The polyimide disclosed by the application is used for preparing the gas separation composite membrane, so that the method is convenient and fast, the material consumption of a separation layer is greatly saved, and the polyimide has a wide application prospect.

Inventors

  • WANG LINA
  • JIE XINGMING
  • LIU DANDAN
  • SONG GUANGLIANG
  • KANG GUODONG
  • CAO YIMING

Assignees

  • 中国科学院大连化学物理研究所

Dates

Publication Date
20260512
Application Date
20241112

Claims (10)

  1. 1. A polymer, characterized in that, The structural unit of the polymer is shown as a formula I: Wherein n is 1-1000; r is a straight chain with the carbon chain length of 50-200; the straight chain consists of a group with a structure of formula A and a group with a structure of formula B; The content of the group with the structure shown in the formula A in the straight chain is 50-100 mol% except 50mol%; when the content of the group having the structure of formula a is 100mol%, the group having the structure of formula B is absent; The number average molecular weight of the polymer is 10000-200000 g/mol; the weight average molecular weight of the polymer is 10000-500000 g/mol; the polydispersity index of the polymer is 1-10.
  2. 2. The polymer according to claim 1, wherein the polymer is, N is 1 to 500; the content of the group with the structure shown in the formula A in the straight chain is 70-100mol%; the number average molecular weight of the polymer is 20000-120000 g/mol; The weight average molecular weight of the polymer is 30000-400 000g/mol; The polydispersity index of the polymer is 1.5-3.5.
  3. 3. The polymer according to claim 1, wherein the polymer is, N is 10-100; The content of the group with the structure shown in the formula A in the straight chain is 80-100 mol%. The number average molecular weight of the polymer is 20000-100000 g/mol; The weight average molecular weight of the polymer is 50000-300000 g/mol; the polydispersity index of the polymer is 1.5-3.
  4. 4. A process for producing a polymer according to any one of claim 1 to 3, The method comprises the following steps: Mixing 4,4 '-methylenebis (2-methyl-6-ethylaniline), 2' -bis (3, 4-dicarboxyphenyl) hexafluoropropane dianhydride and N-methylpyrrolidone, reacting, heating and refluxing, washing and drying to obtain the polymer.
  5. 5. The method according to claim 4, wherein, The molar ratio of the 4,4 '-methylenebis (2-methyl-6-ethylaniline) to the 2,2' -bis (3, 4-dicarboxyphenyl) hexafluoropropane dianhydride is 1:0.9-1; The dosage ratio of the 4,4' -methylenebis (2-methyl-6-ethylaniline) to the N-methylpyrrolidone is 1 mol:2500-3000 ml; The reaction temperature is 20-200 ℃; The reaction time is 16-24 hours; the temperature of the heating reflux is 180-200 ℃; The heating reflux time is 8-16 h; The drying temperature is 150-250 ℃; The drying time is 24-48 h.
  6. 6. A chlorine-containing polyimide gas separation composite membrane is characterized in that, A polymer according to any one of claims 1 to 3.
  7. 7. A process for producing a chlorine-containing polyimide gas separation composite membrane according to claim 6, characterized in that, The method comprises the following steps: And mixing the polymer with a solvent to obtain coating liquid, coating the coating liquid on the surface of the base film by a dip-coating method, and drying to obtain the chlorine-containing polyimide gas separation composite film.
  8. 8. The method according to claim 7, wherein, The solvent is at least one of trichloroethylene, acetone, benzene and toluene; the concentration of the polymer in the coating liquid is 1-10wt%; Preferably, in the coating liquid, the concentration of the polymer is 1-5wt%; preferably, in the coating liquid, the concentration of the polymer is 1-3wt%; the coating temperature is 25-30 ℃; the coating time is 5-60 seconds; Preferably, the coating time is 5-30 seconds; preferably, the coating time is 5-20 seconds; the vacuum degree of the coating is 0 to-0.08 Mpa; preferably, the vacuum degree of the coating is 0 to-0.06 Mpa; The drying temperature is 25-30 ℃; the drying time is 0.5-2 h.
  9. 9. The method according to claim 7, wherein, The material of the base film is at least one selected from polysulfone, polyvinylidene fluoride acetic acid, polyacrylonitrile and polyetherimide; the base membrane is an ultrafiltration membrane or a microfiltration membrane; The aperture of the base film is 0.001-1 mu m; Preferably, the pore diameter of the base film is 0.01-0.2 mu m; preferably, the pore diameter of the base film is 0.01-0.05 μm.
  10. 10. A use of the chlorine-containing polyimide gas separation composite membrane according to claim 6, wherein, Is used for air separation, hydrogen separation, decarbonization and rare gas concentration.

Description

Polymer, chlorine-containing polyimide gas separation composite membrane, and preparation method and application thereof Technical Field The application relates to a polymer, chlorine-containing polyimide gas separation composite membrane, and a preparation method and application thereof, and belongs to the field of gas separation membranes. Background The membrane separation technology has the advantages of no phase change, low energy consumption and the like, and has huge industrial application potential in the field of gas separation. Among the film materials, polyimide is used as a polymer material, has excellent comprehensive performance, such as good gas selectivity, high glass transition temperature, good thermal stability and excellent chemical resistance, and can be processed and molded by various methods, thus being a good film-making material. From the middle of the 80 s of the last century, polyimides began to work well in a number of separation systems with strong industrial settings, H2/N2、O2/N2、He/CH4、CO2/N2、CO2/CH4, etc. Polyimide has various types and forms, and has many synthetic routes, and thus can be selected according to various application purposes, and it is difficult to provide other polymers having such synthetic flexibility. The polyimide is prepared with aromatic heterocyclic polymer prepared with binary anhydride and diamine and through polycondensation, and the two kinds of monomer are compared with other heterocyclic polymer, such as polybenzimidazole, polybenzoxazole, polybenzothiazole, polyquinoline and other monomer. The variety of dianhydride and diamine is various, and polyimide with different performances can be obtained by different combinations. The aromatic polyimide has high separation performance on various gases due to the screening effect of the rigid main chain on different molecules, and has wide application prospect in the field of gas separation. For the polymer gas separation membranes, the permeability and selectivity are contradictory (trade-off phenomenon), i.e., polymer membranes with high permeability often have low separation selectivity, while polymer membranes with high separation selectivity often have very low permeability. The polyimide gas separation membrane has good selectivity, but lower permeability, so that the ideal performance is affected, and the application value of the polyimide gas separation membrane in the aspect of gas separation is seriously affected. Polyimide macromolecules have rich structures, and gas separation membrane materials with excellent performances can be obtained through molecular structure design. Based on the above, from the standpoint of molecular design, many scholars introduce special groups capable of destroying symmetry and regularity of molecular structure into polyimide molecular main chains with poor permeability and better separation selectivity so as to reduce acting force between rigid polyimide molecular chains, increase free volume of a membrane and improve permeability, so that a membrane material with high selectivity and permeability is obtained. Polymeric gas separation membranes for industrial applications are generally of asymmetric structure. At present, a defect-free asymmetric polyimide film is obtained, and a phase inversion method is adopted to prepare a gas separation film with a compact functional layer. Polyimide products soluble in organic solvents are selected as the film material. Preparing casting solution with good solvent/additive mixed solution, and obtaining non-defect asymmetric polyimide film by dry-wet phase inversion method. But the surface skin of such membranes tends to be too thick, resulting in a lower gas permeation rate. PEINENANN et al used chlorohydrocarbon as solvent, acetone or toluene as coagulation bath in the nineteenth century of80, and prepared defect-free asymmetric polyetherimide (Ultem) films by dry-wet phase inversion, which had a higher He/CH 4 separation coefficient than that of the homogeneous films. Chlorinated hydrocarbons are toxic and too low a viscosity of Ultem in chlorinated hydrocarbons is detrimental to practical operation. The composite membrane is used for preparing a compact layer and a porous supporting layer respectively, so that the composite membrane becomes an effective way for improving the permeability of the gas separation membrane. Compared with an asymmetric membrane prepared by a phase inversion method, the composite membrane has the following characteristics: (1) When the price of the selected separation membrane material is higher, the support layer material of the composite membrane can be made of cheap materials, so that a large amount of expensive materials are saved; (2) The range of the asymmetric membrane material is widened, and some materials are difficult to prepare into an asymmetric membrane by a phase inversion method, for example, the material is brittle, and at the moment, an asymmetric form can be realized by prepari