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CN-121319428-B - Liquid crystal elastomer composite material and preparation method thereof

CN121319428BCN 121319428 BCN121319428 BCN 121319428BCN-121319428-B

Abstract

The invention discloses a liquid crystal elastomer composite material and a preparation method thereof, and relates to the technical field of liquid crystal elastomers. The preparation method comprises the steps of synthesizing ionic liquid functionalized liquid crystal monomers containing double bonds through multi-step reaction, preparing a UiO-66 type metal organic framework material, sequentially carrying out amination, maleic anhydride modification and lithium salt adsorption to obtain modified MOFs, finally carrying out dispersion reaction on the ionic functionalized liquid crystal monomers, the modified MOFs, a cross-linking agent, a photoinitiator and a catalyst in tetrahydrofuran to obtain liquid crystal oligomer dispersion liquid, casting, drying to form a film, and carrying out stretching orientation and ultraviolet crosslinking curing to obtain the final composite material. The invention has the advantages that a continuous ion transmission path is constructed on a molecular level through chemical bond grafting, and a macroscopic ion channel is provided by utilizing the porous MOFs material, so that the ion conductivity of the material is obviously improved through the synergistic effect of the porous MOFs material and the macroscopic ion channel.

Inventors

  • XU ZHENTIAN
  • ZHANG LINJUN
  • ZHOU DAN
  • LIU HUI
  • TANG HAO

Assignees

  • 豫章师范学院

Dates

Publication Date
20260512
Application Date
20251127

Claims (9)

  1. 1. The preparation method of the liquid crystal elastomer composite material is characterized by comprising the following steps of: s1, reacting 4-hydroxybenzoic acid, 3-bromopropanol and anhydrous potassium carbonate in acetone, filtering, concentrating, acidifying, washing and drying to obtain 4- (3-hydroxypropoxy) benzoic acid, reacting 4- (3-hydroxypropoxy) benzoic acid with acrylic anhydride under the catalysis of p-toluenesulfonic acid, and distilling, recrystallizing and drying to obtain 4- (3-acryloxypropoxy) benzoic acid; s2, adding 4- (3-acryloyloxy propoxy) benzoic acid and 2-methyl-1, 4-benzenediol into a toluene-DMF mixed solvent, carrying out dehydration reaction under the catalysis of toluene sulfonic acid, cooling, adding triethylamine, then dropwise adding hexamethylenediamine for heat preservation reaction, and obtaining a liquid crystal monomer precursor containing diamino through precipitation, washing, recrystallization and drying; S3, reacting 1-methylimidazole with 1, 6-dibromohexane in acetonitrile, distilling to remove impurities to obtain a bromoimidazole ionic liquid precursor, stirring and reacting a bisamino-containing liquid crystal monomer precursor with the bromoimidazole ionic liquid precursor in N, N-dimethylformamide, filtering, washing and drying to obtain an ionic liquid functionalized liquid crystal intermediate, stirring and reacting the ionic liquid functionalized liquid crystal intermediate with lithium bis (trifluoromethanesulfonyl) imide in acetonitrile, distilling and drying to obtain an ionic functionalized liquid crystal monomer; S4, adding ZrCl4 and terephthalic acid into N, N-dimethylformamide, adding concentrated hydrochloric acid to regulate pH, performing solvothermal reaction, filtering, washing and drying to obtain UiO-66 MOFs, performing ultrasonic dispersion on the UiO-66 MOFs in an ethanol-water mixed solvent, adding 3-aminopropyl triethoxysilane to react, and filtering, washing and drying to obtain NH2-UiO-66; S5, heating NH2-UiO-66 and maleic anhydride in tetrahydrofuran for reaction, filtering, washing and drying to obtain MA-MOFs, adding the MA-MOFs into an N, N-dimethylformamide solvent, performing ultrasonic dispersion, sequentially adding 4-hydroxybiphenyl acrylate, EDC and 4-dimethylaminopyridine, stirring at room temperature for reaction, filtering, washing and drying after the reaction is finished to obtain pretreated MA-MOFs; S6, performing ultrasonic dispersion on the ionic functional liquid crystal monomer, the modified MOFs, pentaerythritol tetrathioglycolate, irgacure369 and di-n-propylamine in tetrahydrofuran, sealing, performing light-shielding stirring reaction to obtain a liquid crystal oligomer dispersion, pouring the liquid crystal oligomer dispersion into a mould, performing vacuum drying, desolventizing, cooling and stripping to obtain a film, performing unidirectional stretching on the film, maintaining the stretched state, performing ultraviolet irradiation cross-linking polymerization, and cooling to obtain the liquid crystal elastomer composite material.
  2. 2. The method for preparing a liquid crystal elastomer composite according to claim 1, wherein in the step S1, the mass ratio of 4-hydroxybenzoic acid to 3-bromopropanol is 35 (40-45).
  3. 3. The method for preparing a liquid crystal elastomer composite according to claim 1, wherein in the step S1, the mass ratio of 4- (3-hydroxypropoxy) benzoic acid to acrylic anhydride is 40 (15-20).
  4. 4. The method for preparing a liquid crystal elastomer composite according to claim 1, wherein in the step S2, the mass ratio of 4- (3-acryloxypropoxy) benzoic acid to 2-methyl-1, 4-benzenediol is 55 (10-15).
  5. 5. The method for preparing a liquid crystal elastomer composite according to claim 1, wherein in the step S3, the mass ratio of the bisamino-containing liquid crystal monomer precursor to the bromoimidazole ion liquid precursor is 35 (30-35).
  6. 6. The method for preparing a liquid crystal elastomer composite according to claim 1, wherein in the step S4, the mass ratio of ZrCl4 to terephthalic acid is 12 (8-10).
  7. 7. The method for preparing a liquid crystal elastomer composite according to claim 1, wherein in the step S5, the mass ratio of NH2-UiO-66 to maleic anhydride is 4 (3-4).
  8. 8. The method for preparing a liquid crystal elastomer composite according to claim 1, wherein in the step S6, the mass ratio of the ionic functional liquid crystal monomer to the modified MOFs is 60 (8-12).
  9. 9. A liquid crystal elastomer composite material prepared by the method of any one of claims 1 to 8.

Description

Liquid crystal elastomer composite material and preparation method thereof Technical Field The invention relates to the technical field of liquid crystal elastomers, in particular to a liquid crystal elastomer composite material and a preparation method thereof. Background Under the dual drive of global double-carbon target introduction and consumer electronics technology iteration, the industries of new energy automobiles, portable electronic equipment, large energy storage power stations and the like realize explosive growth. The fields put forward more severe multidimensional requirements on the performance of the lithium ion battery with the core energy component, namely the energy density is required to be continuously broken through to prolong the endurance mileage or the service time, the cycle life is required to be matched with the full life cycle of equipment to reduce the replacement cost, and the safety performance becomes a core base line for guaranteeing the user benefits and the industrial large-scale popularization. The traditional lithium ion battery generally adopts a liquid electrolyte system, and a liquid matrix composed of an organic solvent, lithium salt and an additive has certain advantages in ion conduction efficiency, but the potential safety hazard caused by essential defects is difficult to eradicate all the time. The liquid electrolyte is easy to volatilize and inflammable, when the battery is influenced by collision, extrusion, overcharge and overdischarge or high-temperature environment, liquid leakage, fire and even explosion are extremely easy to occur, and more importantly, a liquid system cannot effectively inhibit the growth of lithium dendrites on the surface of a lithium metal negative electrode, and the dendrites pierce a diaphragm to cause internal short circuit, so that thermal runaway chain reaction is often triggered, serious threat is brought to the running safety of a new energy automobile and the daily use of electronic equipment, and the liquid system becomes a bottleneck for restricting the high-quality development of related industries. Under the background, the solid electrolyte is a core technical path for breaking the safety problem of the battery by virtue of the solid state form and unique physicochemical properties of the solid electrolyte. Unlike liquid electrolyte, the solid electrolyte has no fluidity, so that the leakage risk is radically eliminated, most solid electrolyte materials are incombustible, the probability of fire disaster caused by thermal runaway is greatly reduced, and meanwhile, the compact microstructure and good interface compatibility of the solid electrolyte can effectively prevent the growth and penetration of lithium dendrites, so that the cycle stability and safety of the battery are further improved. In addition, the solid electrolyte can be also matched with a lithium metal anode with high specific capacity, so that a larger space is opened up for improving the energy density of the battery, and the solid electrolyte is regarded as a core key material of next-generation high-performance lithium ion batteries. The liquid crystal elastomer is taken as an intelligent soft material with liquid crystal ordering and elastomer flexibility, and has very attractive application potential in the field of solid electrolyte. The internal molecular chains can form a highly oriented ordered structure under external stimulus (such as temperature and electric field), the orderly arranged molecular network can construct continuous and smooth ion transmission channels to provide a low-resistance path for lithium ion migration, and meanwhile, the flexible characteristics of the elastomer enable the elastomer to have good mechanical compatibility, can adapt to the deformation requirement in the cell packaging process, relieve the stress concentration of an electrode and electrolyte interface and improve the interface contact stability. However, the current liquid crystal elastomer solid electrolyte for lithium ion batteries still faces a core performance bottleneck, namely low ionic conductivity, and the low conduction efficiency leads to that the battery cannot match with the electrode reaction rate in a high-rate charge-discharge scene (such as fast charge of a new energy automobile and instantaneous power supply of high-power electronic equipment), so that not only can significant voltage drop and energy loss be caused, but also the problems of overlong charge-discharge time, excessively rapid rate performance decay and the like can be caused, the actual requirements of a terminal product on high-power output and fast energy compensation are difficult to meet, and the commercialized application process of the battery is limited. Disclosure of Invention The invention aims to provide a liquid crystal elastomer composite material and a preparation method thereof, which are used for solving the technical problems of the background technology. The