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CN-121991344-A - Amino-terminated hyperbranched polyamic acid as well as preparation method and application thereof

CN121991344ACN 121991344 ACN121991344 ACN 121991344ACN-121991344-A

Abstract

The invention discloses an amino-terminated hyperbranched polyamic acid and a preparation method and application thereof. The amino-terminated hyperbranched polyamide acid is formed by polymerizing an aromatic anhydride monomer, an aromatic triamine monomer and an aromatic diamine monomer, wherein the molar numbers of the aromatic anhydride monomer, the aromatic triamine monomer and the aromatic diamine monomer are a, b and c respectively, wherein the ratio of a (b+c) =1:1-1:1.5, and the ratio of b to c is any ratio. The amino-terminated hyperbranched polyamic acid not only has rich terminal amino groups, but also contains a large number of polar groups such as ether bonds, imidazole rings, amide groups, carboxyl groups and the like in the molecular chain. Therefore, stable hydrocolloid emulsion can be formed in the presence of water and a small amount of organic solvent, other auxiliary agents are not needed, and the interface performance and mechanical property of the composite material can be greatly improved.

Inventors

  • ZHANG JIN
  • ZHOU FANG
  • CAO JIANPING
  • JIAO KUN

Assignees

  • 北京大学
  • 北京石墨烯研究院

Dates

Publication Date
20260508
Application Date
20241108

Claims (10)

  1. 1. The amino-terminated hyperbranched polyamic acid is characterized by being polymerized from an aromatic anhydride monomer, an aromatic triamine monomer and an aromatic diamine monomer, wherein the molar numbers of the aromatic anhydride monomer, the aromatic triamine monomer and the aromatic diamine monomer are a, b and c respectively, wherein a (b+c) =1:1-1:1.5, and the ratio of b to c is any ratio.
  2. 2. The amino-terminated hyperbranched polyamic acid according to claim 1, wherein the aromatic anhydride monomer is one or more of 4,4'- (hexafluoroisopropenyl) diphthalic anhydride, 4' -diphenyl ether dianhydride, 3'4,4' -benzophenone tetracarboxylic dianhydride, 3', 4' -diphenyl sulfone tetracarboxylic dianhydride, 4'- (4, 4' -isopropyldiphenoxy) diphthalic anhydride; The aromatic triamine monomer is one or more of 2,4, 6-triaminopyrimidine, tri (4-aminophenyl) amine and 1,3, 5-tri (4-aminophenyl) benzene; The aromatic diamine monomer is one or more of 1, 4-bis (4-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 4' -diaminodiphenyl ether, p-phenylenediamine, anthracene-2, 6-diamine, 4-chloro-1, 3-phenylenediamine and 5-amino-2- (4-aminophenyl) benzimidazole.
  3. 3. A process for the preparation of the amino-terminated hyperbranched polyamic acid according to claim 1 or 2, comprising: Dissolving the aromatic triamine monomer and the aromatic diamine monomer in a first organic solvent to form a first solution; dissolving the aromatic anhydride monomer in a second organic solvent to form a second solution; Dripping the second solution into the first solution for 1-2 hours; And continuously carrying out polymerization reaction for 6-24 hours at the temperature of-10 ℃ under the condition of mechanical stirring to obtain the organic solution of the amino-terminated hyperbranched polyamic acid.
  4. 4. The method according to claim 3, wherein the total mass of the aromatic acid anhydride monomer, the aromatic triamine monomer, and the aromatic diamine monomer is m4, and the total mass of the first organic solvent and the second organic solvent is m5, wherein m4:m5=1:15 to 1:34; the first organic solvent and the second organic solvent are respectively and independently any one or more of N-methyl pyrrolidone, N-dimethylformamide and N, N-dimethylacetamide.
  5. 5. A sizing agent comprising the amino-terminated hyperbranched polyamic acid according to claim 1 or 2, a third organic solvent, and water.
  6. 6. The sizing agent according to claim 5, wherein the mass of the amino-terminated hyperbranched polyamic acid, the mass of the third organic solvent, and the mass of water are m1, m2, and m3, respectively, wherein m1:m2=1:30 to 1:62, and m1 (m1+m2+m3) =1:100 to 1:100000.
  7. 7. A method of preparing the sizing agent of claim 5 or 6, comprising: adding a fourth organic solvent into the organic solution of the amino-terminated hyperbranched polyamic acid obtained in the claim 3 or 4 for dilution, and then adding deionized water to obtain the sizing agent; Or, adding deionized water into the organic solution of the amino-terminated hyperbranched polyamic acid obtained in the claim 3 or 4 to obtain the sizing agent.
  8. 8. A method for modifying an aramid fiber, comprising: The sizing agent of claim 5 or 6 is adopted to carry out surface sizing treatment on the aramid fiber, and then the aramid fiber is dried to cause amino-terminated hyperbranched polyamic acid in the sizing agent to generate thermal imidization to form amino-terminated hyperbranched polyimide, and the amino-terminated hyperbranched polyimide is coated on the surface of the aramid fiber.
  9. 9. The method for modifying an aramid fiber according to claim 8, wherein the mass ratio of the amino-terminated hyperbranched polyimide coated on the surface of the aramid fiber to the aramid fiber is 0.005-0.015.
  10. 10. A modified aramid fiber obtained by the modification method according to claim 8 or 9.

Description

Amino-terminated hyperbranched polyamic acid as well as preparation method and application thereof Technical Field The invention belongs to the field of polymers and composite materials, and particularly relates to amino-terminated hyperbranched polyamic acid and a preparation method and application thereof. Background The aramid fiber is called as aromatic polyamide fiber, and has the excellent performances of super-high strength, high modulus, high temperature resistance, acid and alkali resistance, light weight and the like. The preparation of the resin-based high-performance composite material as the reinforcement is one of the most important application fields of the aramid fiber. The aramid fiber composite material has more application in the aspects of aerospace, construction, transportation and the like. In addition, the aramid fiber has high crystallinity and smooth surface, so that a stable interface phase cannot be formed with matrix resin, and the aramid fiber composite material has lower interface bonding strength and is easy to generate layering when loaded. At present, the surface treatment method of the aramid fiber comprises chemical modification treatment, plasma treatment, a ray radiation method and surface sizing treatment. The first three surface treatment methods improve the polarity of the fiber surface and increase the roughness of the fiber surface at the expense of the mechanical property of the aramid fiber, however, the surface sizing treatment is to coat a thin resin layer on the fiber surface, and the structure of the aramid fiber is not damaged. However, commercial sizing agents for aramid fibers are still in the right-to-start stage, and therefore, development of an aramid fiber sizing agent for industrial production is urgent. Disclosure of Invention The invention aims to overcome the defects of the prior art, provides amino-terminated hyperbranched polyamic acid, can greatly improve the interfacial bonding strength of aramid fiber and matrix resin as a sizing agent, and provides a preparation method and application of the amino-terminated hyperbranched polyamic acid. The first aspect of the invention provides an amino-terminated hyperbranched polyamic acid, which is polymerized by an aromatic anhydride monomer, an aromatic triamine monomer and an aromatic diamine monomer, wherein the molar numbers of the aromatic anhydride monomer, the aromatic triamine monomer and the aromatic diamine monomer are a, b and c respectively, wherein a (b+c) =1:1-1:1.5, and the ratio of b to c is any ratio. According to one embodiment of the invention, the aromatic anhydride monomer is 4,4' - (hexafluoroisopropenyl) diphthalic anhydride, 4' -diphenyl ether dianhydride, 3'4,4' -benzophenone tetracarboxylic dianhydride, 3', one or more of 4,4' -diphenyl sulfone tetracarboxylic dianhydride, 4' - (4, 4' -isopropyl diphenoxy) diphthalic anhydride; the aromatic triamine monomer is one or more of 2,4, 6-triaminopyrimidine, tri (4-aminophenyl) amine and 1,3, 5-tri (4-aminophenyl) benzene, and the aromatic diamine monomer is one or more of 1, 4-bis (4-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 4' -diaminodiphenyl ether, p-phenylenediamine, anthracene-2, 6-diamine, 4-chloro-1, 3-phenylenediamine and 5-amino-2- (4-aminophenyl) benzimidazole. The second aspect of the invention provides a preparation method of amino-terminated hyperbranched polyamic acid, which comprises the steps of dissolving an aromatic triamine monomer and an aromatic diamine monomer in a first organic solvent to form a first solution, dissolving an aromatic anhydride monomer in a second organic solvent to form a second solution, dripping the second solution into the first solution for 1-2 hours, and continuously carrying out polymerization reaction for 6-24 hours at-10 ℃ under the condition of mechanical stirring to obtain an organic solution of the amino-terminated hyperbranched polyamic acid. According to one embodiment of the invention, the total mass of the aromatic anhydride monomer, the aromatic triamine monomer and the aromatic diamine monomer is m4, the total mass of the first organic solvent and the second organic solvent is m5, wherein m4:m5=1:15-1:34, and the first organic solvent and the second organic solvent are respectively and independently any one or more of N-methylpyrrolidone (NMP), N-Dimethylformamide (DMF) and N, N-dimethylacetamide (DMAc). The third aspect of the invention provides a sizing agent comprising the amino-terminated hyperbranched polyamic acid, a third organic solvent and water. According to one embodiment of the present invention, the mass of the amino-terminated hyperbranched polyamic acid, the mass of the third organic solvent, and the mass of the water are m1, m2, and m3, respectively, wherein m1:m2=1:30 to 1:62, and m1 (m1+m2+m3) =1:100 to 1:100000. The fourth aspect of the invention provides a preparation method of a sizing agent, which comprises the steps of diluting an organic so