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CN-119529369-B - Liquid crystal polyimide aerogel with excellent shape memory performance and preparation method thereof

CN119529369BCN 119529369 BCN119529369 BCN 119529369BCN-119529369-B

Abstract

The invention discloses a liquid crystal polyimide aerogel with excellent shape memory performance and a preparation method thereof, and belongs to the field of polymer aerogel materials. The liquid crystal polyimide aerogel with excellent shape memory performance is prepared through the steps of reacting liquid crystal diamine, flexible diamine, liquid crystal dianhydride monomer and thermosetting agent to obtain dry polyamide acid filament, injecting the dry polyamide acid filament into a silica gel mold to form water solution, performing directional freezing casting on a custom freezing circulation device with copper plate at the top, and freeze drying, thermal imidization and solidification after molding.

Inventors

  • LI LE
  • CHEN WEI
  • LIU TIANXI
  • FAN WEI
  • WANG XIANG

Assignees

  • 江南大学

Dates

Publication Date
20260505
Application Date
20241118

Claims (7)

  1. 1. The liquid crystal polyimide aerogel with excellent shape memory performance is characterized in that the shape fixation rate of the liquid crystal polyimide aerogel is more than or equal to 99 percent, the shape recovery rate is more than or equal to 97 percent, and the thermal conductivity at room temperature is more than or equal to 0.09W m -1 K -1 ; The preparation method of the liquid crystal polyimide aerogel with excellent shape memory performance comprises the following steps: (1) The liquid crystal diamine, the flexible diamine monomer and the liquid crystal dianhydride monomer are combined in N Performing polycondensation reaction in methyl pyrrolidone, adding a thermosetting agent after the reaction, and continuing the reaction to obtain polyamic acid solution; the liquid crystal dianhydride monomer is 4,4' -terephthaloyl diphthalic anhydride; The thermosetting agent is one or two of 4-ethynylaniline and nadic anhydride; (2) Adding the polyamide acid dry filaments obtained in the step (1) and triethylamine into ultrapure water, heating and stirring uniformly to obtain a polyamide acid aqueous solution; The concentration of the polyamide acid in the aqueous solution of the polyamide acid is 100-120 mg/ml; (3) Injecting the aqueous solution of polyamide acid obtained in the step (2) into a silica gel mold, placing the mold on a custom refrigeration cycle device with a copper plate at the top for directional refrigeration casting, and placing the mold into a freeze dryer for freeze drying after molding to obtain polyamide acid aerogel; the temperature of the directional freezing casting is 120~ 20 ℃ For 1-24h; (4) And (3) performing thermal imidization and thermal curing on the polyamic acid aerogel obtained in the step (3) to obtain the liquid crystal polyimide aerogel, namely the liquid crystal polyimide aerogel with excellent shape memory performance.
  2. 2. A method for preparing the liquid crystal polyimide aerogel having excellent shape memory properties according to claim 1, comprising the steps of: (1) The liquid crystal diamine, the flexible diamine monomer and the liquid crystal dianhydride monomer are combined in N Performing polycondensation reaction in methyl pyrrolidone, adding a thermosetting agent after the reaction, and continuing the reaction to obtain a polyamic acid solution, performing solvent replacement on the polyamic acid solution, and then freezing and freeze-drying to obtain polyamic acid dry filaments, wherein the liquid crystal dianhydride monomer is 4,4' -terephthaloyl bisphthalic anhydride; The thermosetting agent is one or two of 4-ethynylaniline and nadic anhydride; (2) Adding the polyamide acid dry filaments obtained in the step (1) and triethylamine into ultrapure water, heating and stirring uniformly to obtain an aqueous solution of polyamide acid, wherein the concentration of the polyamide acid in the aqueous solution of polyamide acid is 100-120 mg/ml; (3) Injecting the aqueous solution of polyamide acid obtained in the step (2) into a silica gel mold, placing the mold on a custom refrigeration cycle device with a copper plate at the top for directional refrigeration casting, and placing the mold into a freeze dryer for freeze drying after molding to obtain polyamide acid aerogel; the temperature of the directional freezing casting is 120~ 20 ℃ For 1-24h; (4) And (3) performing thermal imidization and thermal curing on the polyamic acid aerogel obtained in the step (3) to obtain the liquid crystal polyimide aerogel, namely the liquid crystal polyimide aerogel with excellent shape memory performance.
  3. 3. The method of claim 2, wherein the liquid crystalline diamine monomer of step (1) is one or both of 1, 3-bis (4-aminophenoxy) benzene, 1, 4-bis (4-aminophenoxy) benzene.
  4. 4. The method of claim 2, wherein the flexible diamine monomer of step (1) is 1, 3-bis (3-aminophenoxy) benzene.
  5. 5. The method of claim 2, wherein the molar ratio of the liquid crystalline diamine monomer to the flexible diamine monomer in step (1) is 1 (0-1) and the molar ratio of the liquid crystalline diamine monomer to the liquid crystalline dianhydride monomer is 1 (0.95-2.5).
  6. 6. The method of claim 2, wherein the molar ratio of the liquid crystalline diamine to the thermosetting agent in step (1) is 1 (0-0.1).
  7. 7. The liquid crystal polyimide aerogel with excellent shape memory performance as claimed in claim 1 or the liquid crystal polyimide aerogel prepared by the preparation method as claimed in any one of claims 2 to 6 is applied to heat insulation materials, aerospace vehicles, expandable panels and light intelligent deformation materials.

Description

Liquid crystal polyimide aerogel with excellent shape memory performance and preparation method thereof Technical Field The invention relates to a liquid crystal polyimide aerogel with excellent shape memory performance and a preparation method thereof, belonging to the field of polymer aerogel materials. Background The shape memory polymer aerogel with high porosity is a novel special material with ultralow density, combines the unique performance (such as ultralow density, high specific surface area and porosity) of the aerogel with the bright spots of the polymer in the aspect of shape memory, and has a plurality of application prospects in the fields of sensors, bionic structures, expandable panels and the like. However, research on shape memory polymer aerogel is mainly focused on materials such as polyurethane, polycaprolactone and nanocellulose, and the shape memory aerogel prepared from the materials has the problems of poor mechanical properties, low transition temperature (less than 120 ℃) and the like, and cannot meet the requirements of aerospace or other high-temperature scenes. The polyimide is one of organic polymer materials with optimal comprehensive performance, has excellent thermal stability and high temperature resistance of more than 400 ℃, can be used for a long time at a temperature range of-200-300 ℃, has excellent mechanical properties and the like, and most importantly, has a rigid structure so that the T g of the polyimide is generally higher than 200 ℃. Therefore, the preparation of the shape memory aerogel by using polyimide is expected to expand the application of the shape memory polymer aerogel in aerospace and other high-temperature fields. The aerogel material prepared from polyimide has the advantages of light weight, high strength, strong molecular designability, low dielectric constant and the like, but polyimide aerogel is a high-porosity heat insulation material, has the problem of low heat conductivity and is contradictory to shape memory rapid thermal response. If the thermal conductivity of the polyimide aerogel can be properly improved, the contradiction of slow response speed caused by slow heat transfer in a polyimide aerogel framework can be alleviated, so that the polyimide aerogel with shape memory performance can be prepared, and the application of the polyimide aerogel in a space intelligent structure can be promoted. At present, a mode of improving the heat conductivity of polyimide-based materials is mainly to prepare polyimide-based heat conducting composite materials by filling heat conducting materials, and the mode generally needs to add a large amount of heat conducting fillers to obtain ideal heat conductivity coefficients, which inevitably leads to the reduction of mechanical and processing performances, and limits the wider application of the polyimide-based heat conducting composite materials. Disclosure of Invention [ Technical problem ] The prior shape memory polyimide aerogel mainly comprises polyimide-based composite aerogel and pure polyimide aerogel. The polyimide-based composite aerogel is mainly prepared by filling a large amount of filler in the polyimide aerogel, so that the heat conduction performance is obviously improved, but a large improvement space still exists for the shape memory performance. The reported pure polyimide aerogel is mainly prepared by designing the molecular structure of the polyimide aerogel, the shape memory performance of the polyimide aerogel is excellent, but the heat conducting performance of the polyimide aerogel is not obviously improved, and the shape recovery rate is low. Technical scheme Aiming at the defects and shortcomings in the prior art, the invention aims to improve the heat conductivity of the shape memory polyimide aerogel, balance the contradiction between the low heat conductivity of the polyimide aerogel and the quick heat response required by shape memory, and improve the problems of poor shape memory performance and the like of the polyimide aerogel, so as to prepare the polyimide aerogel material with excellent shape memory performance and promote the application of the polyimide aerogel material in the field of light intelligent deformation materials. The preparation method comprises the steps of copolymerizing liquid crystal diamine, flexible diamine and liquid crystal dianhydride monomers, adding a thermosetting agent for continuous reaction after reaction to obtain polyamic acid solution, carrying out solvent replacement on the polyamic acid solution in ultrapure water, freezing and drying to obtain polyamic acid dry filaments, preparing the polyamic acid dry filaments and triethylamine into polyamic acid aqueous solution, injecting the polyamic acid aqueous solution into a silica gel mold, carrying out directional freezing casting on a custom freezing circulation device with a copper plate at the top, and carrying out freeze drying, thermal imidization and solidification after moldin