Topological chemical polymerization method based on discotic liquid crystal

Abstract

The invention discloses a topological chemical polymerization method based on discotic liquid crystals, and relates to the technical field of liquid crystal polymers. The method comprises the following steps: dissolving 3, 4, 5-tri (hexyloxy) phenylacetonitrile and 1, 3, 5-benzenetricarboxaldehyde in ethanol, adding tetrabutyl ammonium hydroxide, and reacting at 50-60 DEG C for 1-3 hours to obtain a discotic liquid crystal monomer; placing the discotic liquid crystal monomer on a substrate, heating the discotic liquid crystal monomer until the temperature is greater than or equal to 200 DEG C to enable the discotic liquid crystal monomer to be in a molten state, then pressing the discotic liquid crystal monomer to form a thin film, then cooling the discotic liquid crystal monomer to 70-80 DEG C, and then irradiating the thin film sample for 12-48 hours by using ultraviolet light to obtain the one-dimensional polymer material based on the topological chemical polymerization of the discotic liquid crystal. According to the method, the application range of topological chemical polymerization is widened, more adjustability is given to the topological chemical polymerization process, and new possibility is provided for the field of topological chemistry.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid crystal polymers, and particularly to a topochemical polymerization method based on discotic liquid crystals. Background Art

[0002] Topochemical polymerization is a solid-state reaction driven by the arrangement of crystalline monomers. With the help of spatial constraints in the monomer lattice, it can precisely control the stereoregularity, packing structure, and crystallinity of polymers. Such reactions generally do not require solvents or catalysts, can efficiently and highly selectively generate target products, and avoid the cumbersome chromatographic purification steps in traditional solution polymerization processes. Therefore, topochemical polymerization shows higher practical value in synthesizing polymers with complex structures and specific topological features. However, the realization of topochemical polymerization depends on precisely controlling the orientation, arrangement pattern, and lattice spacing of monomers, which limits its application scope. Liquid crystals, as a unique phase state between the crystalline and liquid states, possess both the orderliness of crystalline substances and the fluidity of liquids. Therefore, the dynamic ordered structure of liquid crystals provides a new solution to overcome the problems of molecular orientation and spacing in topochemical polymerization.

[0003] The prior art discloses a visible-light-triggered topochemical polymerization reaction based on conjugated dye molecules, and successfully obtains high-quality polymer single crystals with macroscopic sizes. In addition, the polymer can decompose into monomers during pyrolysis, indicating that the polymerization-depolymerization process is reversible. However, this polymerization method depends on precisely controlling the orientation, arrangement pattern, and lattice spacing of monomers, and often requires cultivating large-sized single crystals. These strict topochemical polymerization conditions limit its application scope.

[0004] The prior art also discloses a topochemical polymerization reaction based on a dipeptide modified with azide and alkyne at the ends. The dipeptide self-assembles into a gel through hydrogen bonds in organic solvents and water, and the xerogel undergoes azide-alkyne topochemical polymerization under heating conditions to form 1,4-triazole-linked oligopeptides. However, this topochemical method also faces similar challenges in terms of molecular arrangement orientation, intermolecular distance, etc., limiting the expansion of topochemical polymerization methods. Summary of the Invention

[0005] Aiming at the deficiencies in the above background art, the present invention mainly solves the problems such as molecular orientation and intermolecular distance in the process of topochemical polymerization in the prior art, especially the requirements for crystal arrangement and monomer reactivity in the solid state. The present invention provides a topochemical polymerization method based on discotic liquid crystals. This method not only broadens the application scope of topochemical polymerization, but also endows the topochemical polymerization process with more adjustability, providing new possibilities for the field of topochemistry.

[0006] The first object of the present invention is to provide a topochemical polymerization method based on discotic liquid crystals, comprising the following steps: Dissolve 3,4,5-tris(hexyloxy)benzyl cyanide and 1,3,5-benzenetricarbaldehyde in ethanol, add tetrabutylammonium hydroxide, and react at 50-60 °C for 1-3 h to obtain a discotic liquid crystal monomer; Place the discotic liquid crystal monomer on a substrate, heat it to a temperature ≥200 °C to make the discotic liquid crystal monomer in a molten state, then press it to form a film, and then cool it to 70-80 °C, and then irradiate the film sample with ultraviolet light for 12-48 h, that is, a one-dimensional polymer material is obtained by topochemical polymerization based on discotic liquid crystals.

[0007] Preferably, the molar ratio of 3,4,5-tris(hexyloxy)benzyl cyanide to 1,3,5-benzenetricarbaldehyde is 2-4:1.

[0008] Preferably, the wavelength of the ultraviolet light is 365 nm.

[0009] Preferably, the structural formula of the discotic liquid crystal monomer is: .

[0010] Preferably, the 3,4,5-tris(hexyloxy)benzyl cyanide is prepared according to the following steps: Dissolve 5-(bromomethyl)-1,2,3-tris(hexyloxy)benzene, trimethylsilyl cyanide and tetrabutylammonium fluoride in acetonitrile, stir at room temperature for 2-4 h, remove the solvent, and then obtain 3,4,5-tris(hexyloxy)benzyl cyanide through extraction and purification; The molar ratio of 5-(bromomethyl)-1,2,3-tris(hexyloxy)benzene, trimethylsilyl cyanide and tetrabutylammonium fluoride is 1:1-2:1-2.

[0011] Preferably, the 5-(bromomethyl)-1,2,3-tris(hexyloxy)benzene is prepared according to the following steps: React 3,4,5-tris(hexyloxy)benzyl alcohol with phosphorus tribromide in dichloromethane through bromination reaction to obtain 5-(bromomethyl)-1,2,3-tris(hexyloxy)benzene; The molar ratio of 3,4,5-tris(hexyloxy)benzyl alcohol to phosphorus tribromide is 1:1.

[0012] Preferably, the 3,4,5-tris(hexyloxy)benzyl alcohol is prepared according to the following steps: In a nitrogen atmosphere, dissolve methyl gallate, 1-bromohexane, tetrabutylammonium iodide and potassium carbonate in N,N-dimethylformamide, react at 75-85 °C for 10-24 h, and obtain methyl 3,4,5-tris(hexyloxy)benzoate through extraction and purification; Methyl 3,4,5-tris(hexyloxy)benzoate is used as a raw material, and in a tetrahydrofuran solution, with lithium aluminum hydride as a reducing agent, through a reduction reaction, 3,4,5-tris(hexyloxy)benzyl alcohol is obtained.

[0013] Preferably, the molar ratio of methyl gallate, 1-bromohexane, tetrabutylammonium iodide, and potassium carbonate is 1:4:0.01 - 0.05:6 - 8; The molar ratio of methyl 3,4,5-tris(hexyloxy)benzoate to lithium aluminum hydride is 1:1 - 2.

[0014] The second object of the present invention is to provide a one-dimensional polymer material prepared by a topochemical polymerization method based on discotic liquid crystals.

[0015] The third object of the present invention is to provide an application of the one-dimensional polymer material in high-performance liquid crystal polymer materials.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a topochemical polymerization method based on discotic liquid crystals. This method innovatively introduces liquid crystal molecules with a dynamic ordered structure into the topochemical polymerization system. In the liquid crystal state, liquid crystal molecules can not only maintain a highly ordered molecular arrangement but also have good fluidity and adjustability. They can self-adjust and optimize the molecular positions under specific conditions, providing ideal spatial configurations and geometric conditions for the polymerization reaction. This unique dynamic ordered structure enables liquid crystal molecules to precisely control the distance between reaction sites, thus successfully realizing topochemical polymerization. The obtained one-dimensional polymer material has high hardness and Young's modulus, and there are also dynamic changes in luminescence properties during the preparation process. In particular, the one-dimensional columnar phase structure of discotic liquid crystal molecules can effectively restrict the directionality of topochemical polymerization, which is beneficial to the formation of one-dimensional linear polymers with regular structures. Compared with the prior art, this method breaks through the limitations of traditional topochemical polymerization in molecular arrangement and orientation control, significantly expanding its application prospects in the field of functional polymer material preparation. Description of the Drawings Figure 1 It is a schematic diagram of the topochemical polymerization structure based on discotic liquid crystals of the present invention.

[0017] Figure 2 It is a differential scanning calorimetry curve of the discotic liquid crystal monomer used in Example 1 of the present invention and a small-angle X-ray scattering pattern in the liquid crystal state.

[0018] Figure 3 It is a gel permeation chromatography diagram and a nuclear magnetic resonance hydrogen spectrum of the discotic liquid crystal monomer used in Example 1 of the present invention and the one-dimensional polymer prepared therefrom.

[0019] Figure 4It is a nanoindentation mechanical property characterization diagram of the discotic liquid crystal monomer used in Example 1 of the present invention and the one-dimensional polymer obtained therefrom.

[0020] Figure 5 It is the crystal microscopic image and nuclear magnetic resonance hydrogen spectrum of the discotic liquid crystal monomer used in Example 1 of the present invention after being irradiated with 365 nm ultraviolet light for 24 h in the crystalline state. Specific embodiments

[0021] In order to enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and drawings, but the embodiments cited do not limit the present invention.

[0022] The purpose of the present invention is to provide a topochemical polymerization method based on discotic liquid crystals. This method not only broadens the application scope of topochemical polymerization but also endows the topochemical polymerization process with more adjustability, providing new possibilities for the field of topochemistry.

[0023] To achieve the above purpose, the first aspect of the present invention provides a topochemical polymerization method based on discotic liquid crystals, including the following steps: Dissolve 3,4,5-tris(hexyloxy)benzonitrile and 1,3,5-benzenetricarbaldehyde in ethanol, add tetrabutylammonium hydroxide, and react at 50 - 60 °C for 1 - 3 h to obtain a discotic liquid crystal monomer; Place the discotic liquid crystal monomer on a substrate, heat it to a temperature ≥ 200 °C to make the discotic liquid crystal monomer in a molten state, then press it into a film shape, then cool it to 70 - 80 °C, and then irradiate the film sample with ultraviolet light for 12 - 48 h, that is, a one-dimensional polymer material is obtained by topochemical polymerization based on discotic liquid crystals.

[0024] The molar ratio of the 3,4,5-tris(hexyloxy)benzonitrile to the 1,3,5-benzenetricarbaldehyde is 2 - 4:1.

[0025] The wavelength of the ultraviolet light is 365 nm.

[0026] The structural formula of the discotic liquid crystal monomer is: .

[0027] The 3,4,5-tris(hexyloxy)benzonitrile is prepared according to the following steps: Dissolve 5-(bromomethyl)-1,2,3-tris(hexyloxy)benzene, trimethylcyanosilane, and tetrabutylammonium fluoride in acetonitrile, stir at room temperature for 2 - 4 h, remove the solvent, and then obtain 3,4,5-tris(hexyloxy)benzonitrile through extraction and purification; The molar ratio of 5-(bromomethyl)-1,2,3-tris(hexyloxy)benzene, trimethylsilyl cyanide and tetrabutylammonium fluoride is 1:1~2:1~2.

[0028] The 5-(bromomethyl)-1,2,3-tris(hexyloxy)benzene is prepared according to the following steps: 3,4,5-Tris(hexyloxy)benzyl alcohol and phosphorus tribromide are subjected to a bromination reaction in dichloromethane to obtain 5-(bromomethyl)-1,2,3-tris(hexyloxy)benzene; Among them, the molar ratio of 3,4,5-tris(hexyloxy)benzyl alcohol to phosphorus tribromide is 1:1.

[0029] The 3,4,5-tris(hexyloxy)benzyl alcohol is prepared according to the following steps: In a nitrogen atmosphere, methyl gallate, 1-bromohexane, tetrabutylammonium iodide and potassium carbonate are dissolved in N,N-dimethylformamide and reacted at 75~85 °C for 10~24 h. After extraction and purification, methyl 3,4,5-tris(hexyloxy)benzoate is obtained; Methyl 3,4,5-tris(hexyloxy)benzoate in a tetrahydrofuran solution uses lithium aluminum hydride as a reducing agent and undergoes a reduction reaction to obtain 3,4,5-tris(hexyloxy)benzyl alcohol.

[0030] The molar ratio of methyl gallate, 1-bromohexane, tetrabutylammonium iodide and potassium carbonate is 1:4:0.01~0.05:6~8; The molar ratio of methyl 3,4,5-tris(hexyloxy)benzoate to lithium aluminum hydride is 1:1~2.

[0031] Exemplarily, a topochemical polymerization method based on discotic liquid crystals includes the following steps: Step 1: In a nitrogen atmosphere, methyl gallate, 1-bromohexane, tetrabutylammonium iodide and potassium carbonate with a molar ratio of 1:4:0.03:7.85 are dissolved in N,N-dimethylformamide (DMF), and stirred at 80 °C for 12 hours. The reaction mixture is cooled to room temperature and then poured into water. After extracting 3 times with dichloromethane, the crude product is purified by silica gel column chromatography to obtain white solid methyl 3,4,5-tris(hexyloxy)benzoate; Step 2: A solution of lithium aluminum hydride in tetrahydrofuran (molar ratio 1:1) is added to a tetrahydrofuran solution containing methyl 3,4,5-tris(hexyloxy)benzoate at 0 °C over 0.5 hour, and then stirred at room temperature for another 2 hours. After quenching the reaction with water, the mixture is extracted 3 times with dichloromethane, dried over anhydrous magnesium sulfate, concentrated and dried under vacuum to obtain white solid 3,4,5-tris(hexyloxy)benzyl alcohol.

[0032] Step 3: Add a solution of phosphorus tribromide in dichloromethane (molar ratio 1:1) to the obtained solution of 3,4,5-tris(hexyloxy)benzyl alcohol in dichloromethane at 0 °C over 2 hours, then stir for an additional 3 hours at room temperature. After quenching the reaction with water, extract the mixture 3 times with dichloromethane, dry over anhydrous magnesium sulfate, concentrate, and dry under vacuum to obtain the white solid 5-(bromomethyl)-1,2,3-tris(hexyloxy)benzene.

[0033] Step 4: Dissolve 5-(bromomethyl)-1,2,3-tris(hexyloxy)benzene, trimethylsilyl cyanide, and tetrabutylammonium fluoride in acetonitrile in a molar ratio of 1:1.5:1.5 and stir at room temperature for 2.5 hours. After removing the solvent, add dichloromethane and wash 3 times with water. Finally, purify the crude product by column chromatography on neutral alumina using dichloromethane as the eluent to obtain the white solid 3,4,5-tris(hexyloxy)benzonitrile.

[0034] Step 5: Add tetrabutylammonium hydroxide to a solution of 3,4,5-tris(hexyloxy)benzonitrile and 1,3,5-benzenetricarbaldehyde in ethanol in a molar ratio of 3:1, then stir at 55 °C for 2 hours. Cool the reaction mixture to room temperature and collect the precipitate by filtration. Purify the crude product by silica gel column chromatography to obtain the light yellow solid product (2Z,2'Z,2''-Z)-3,3',3''-(benzene-1,3,5-triyl)tris(2-(3,4,5-tris(hexyloxy)phenyl)acrylonitrile).

[0035] Step 6: Take 5 mg of the solid (2Z,2'Z,2''-Z)-3,3',3''-(benzene-1,3,5-triyl)tris(2-(3,4,5-tris(hexyloxy)phenyl)acrylonitrile) prepared in the previous step on a glass slide and place the glass slide on a hot stage. Heat the sample to the molten state by raising the temperature above 200 °C, then press the sample into a thin film shape. Slowly lower the ambient temperature to 75 °C and keep the temperature constant. Subsequently, irradiate the thin film sample with 365 nm ultraviolet light for 24 h to obtain a one-dimensional polymer material prepared by topochemical polymerization of cyanostilbene discotic liquid crystal monomers.

[0036] All the solutions are heated under the condition of a constant temperature oil bath.

[0037] All the stirring reactions at room temperature are carried out under the condition of a constant temperature 25 °C oil bath.

[0038] The liquid crystal monomer molecules provided by the present invention have a quasi-discoidal configuration, making it easy for them to self-assemble and stack into a one-dimensional columnar structure. Meanwhile, as the temperature rises, the molecules can successively form a columnar crystalline phase, an ordered hexagonal columnar liquid crystal phase, and a disordered hexagonal columnar liquid crystal phase. Under ultraviolet light irradiation, the cyanostyrene molecules in the liquid crystal state can undergo topochemical photopolymerization through intermolecular [2+2] cycloaddition reaction to form a one-dimensional polymer. This topochemical polymerization process also depends on the orderliness of the columnar liquid crystal phase. In the ordered hexagonal columnar liquid crystal phase, the molecules are regularly arranged and have strong interactions, enabling the formation of high-molecular-weight polymers; while in the disordered hexagonal columnar liquid crystal phase, the molecules are relatively loosely arranged and the intermolecular interactions are weak, and only low-molecular-weight oligomers can be generated by polymerization.

[0039] The second aspect of the present invention provides a one-dimensional polymer material prepared by a topochemical polymerization method based on discotic liquid crystals.

[0040] The third aspect of the present invention provides an application of a one-dimensional polymer material in high-performance liquid crystal polymer materials.

[0041] It should be noted that the experimental methods used in the present invention are all conventional methods without special instructions; the reagents and materials used can be purchased on the market without special instructions.

[0042] Example 1 Methyl 3,4,5-trihydroxybenzoate (1.8 g, 9.8 mmol), 1-bromohexane (6.4 g, 39 mmol), tetrabutylammonium iodide (0.1 g, 0.3 mmol), and K2CO3 (11 g, 77 mmol) were added into a 250 mL eggplant-shaped flask, and 100 mL of DMF was added for dissolution. After freeze-pumping with a double-tube for three cycles to remove water and oxygen, the reaction system was sealed and placed in an oil bath, heated to 80 °C, and stirred for 12 h. After the reaction ended and cooled to room temperature, the DMF was removed by rotary evaporation at 80 °C. The crude product was dissolved in dichloromethane, washed 3 times with saturated brine, 100 mL of saturated brine was added each time to thoroughly wash away the salt impurities, and finally the final product was separated and purified by column chromatography. The eluent ratio used was petroleum ether / ethyl acetate 20:1, and methyl 3,4,5-tri(hexyloxy)benzoate, a purified white solid, was obtained.

[0043] Methyl 3,4,5-tris(hexyloxy)benzoate and 40 mL of ultradry THF were added into a 100 mL eggplant-shaped flask. The reaction system was placed in a low-temperature reactor and stirred in an ice bath at 0 °C for 0.5 h. A THF solution of lithium aluminum hydride (1 mol / L, 4 mL) was slowly added in portions. Then the reaction system was transferred to room temperature and stirred for another 2 h. After the reaction was completed, the reaction system was placed in an ice bath at 0 °C, and deionized water was slowly added dropwise to the reaction solution until no bubbles were generated. Then the temperature of the rotary evaporator was adjusted to 50 °C to remove the THF / water mixed solvent. The remaining crude product was dissolved in dichloromethane, and a small amount of dilute hydrochloric acid was added to dissolve the basic insoluble substances therein. It was washed 3 times with saturated brine and dichloromethane, and then the remaining dichloromethane was removed by rotary evaporation and dried under vacuum to obtain white solid 3,4,5-tris(hexyloxy)benzyl alcohol.

[0044] 3,4,5-Tris(hexyloxy)benzyl alcohol and 100 mL of dichloromethane were added into a 150 mL eggplant-shaped flask. The reaction system was placed in a low-temperature reactor and stirred at 0 °C for 10 min. A 25 mL dichloromethane solution containing phosphorus tribromide (0.9 g, 3.4 mmol) was added into a 50 ml constant-pressure dropping funnel, and the solution was slowly added dropwise to the reaction system by adjusting the stopcock. After the addition was completed, the reaction was continued to stir at 0 °C for 2 h, and then stirred at room temperature for 3 h. After the reaction was completed, deionized water was slowly added dropwise to the reaction system in an ice bath at 0 °C until no yellow fumes emerged. The remaining reaction solution was washed 3 times with saturated brine and dichloromethane, and then the dichloromethane in the organic phase was evaporated to dryness and dried under vacuum to obtain white solid 5-(bromomethyl)-1,2,3-tris(hexyloxy)benzene.

[0045] 5-(Bromomethyl)-1,2,3-tris(hexyloxy)benzene, trimethylsilyl cyanide (0.3 ml, 3.8 mmol), and tetrabutylammonium fluoride (1.0 g, 4.0 mmol) were added into a 150 mL eggplant-shaped flask, and 100 mL of acetonitrile was added to fully dissolve the raw materials. The mixture was stirred at room temperature for 2.5 h. After the reaction was completed, the temperature of the rotary evaporator was controlled at 50 °C to remove acetonitrile. The remaining crude product was dissolved in 100 mL of dichloromethane, washed 3 times with saturated brine, with 100 mL of saturated brine added each time. The organic phase was taken and evaporated to dryness, and the crude product was purified by passing through a neutral alumina column using dichloromethane as the eluent to obtain purified white solid 3,4,5-tris(hexyloxy)benzonitrile.

[0046] 3,4,5-Tris(hexyloxy)benzyl cyanide (0.8 g, 1.9 mmol), 1,3,5-benzenetricarbaldehyde (0.09 g, 0.58 mmol), and 50 mL of absolute ethanol were added to a 150 mL eggplant-shaped flask. The reaction system was heated to 55 °C and stirred until the raw materials were completely dissolved. Then, tetrabutylammonium hydroxide (0.6 mL, 2.3 mmol) was added to the reaction system, and stirring was continued for 2 h to fully precipitate the product. After the reaction was completed, the filter cake was obtained by suction filtration. The crude product was dissolved in dichloromethane, and finally, the crude product was purified by passing it through a silica gel-packed column by column chromatography. The eluent ratio used was petroleum ether / ethyl acetate 8:1, and a purified pale yellow solid, (2Z,2'Z,2''-Z)-3,3',3''-(benzene-1,3,5-triyl)tris(2-(3,4,5-tris(hexyloxy)phenyl)acrylonitrile), was obtained.

[0047] Take 5 mg of the solid (2Z,2'Z,2''-Z)-3,3',3''-(benzene-1,3,5-triyl)tris(2-(3,4,5-tris(hexyloxy)phenyl)acrylonitrile) prepared in the previous step on a glass slide and place the glass slide on a hot stage. Heat the sample to the molten state by raising the temperature above 200 °C, and then press the sample into a thin film. Slowly lower the ambient temperature to 75 °C and keep the temperature constant. Subsequently, irradiate the thin film sample with 365 nm ultraviolet light for 24 h, which is a one-dimensional polymer material obtained by the topochemical polymerization method based on cyanostilbene discotic liquid crystal units.

[0048] Example 2 The same as in Example 1, place the monomer on a glass slide and place the glass slide on a hot stage. Heat the sample to the molten state by raising the temperature above 200 °C. The difference is that the ambient temperature is slowly lowered to 175 °C, and the molecules can form a relatively disordered liquid crystal phase stacking mode in the column at this temperature. Keeping other polymerization parameters unchanged, the molecules can also undergo an intermolecular [2+2] cycloaddition reaction under ultraviolet light irradiation. However, due to the relatively loose molecular arrangement and weak intermolecular interaction, only low molecular weight oligomers can be formed by polymerization.

[0049] Comparative Example The crystal formed by the molecules at 0 °C was irradiated with 365 nm ultraviolet light. It can be seen that after 24 h of ultraviolet light irradiation, no significant changes in the morphology size, color, or luminescence characteristics of the crystal sample were found. The 1H NMR spectrum of the crystal after irradiation was also consistent with that of the monomer, indicating that the topochemical polymerization phenomenon does not occur in the low-temperature crystalline state of the molecules.

[0050] To illustrate the relevant properties of the one-dimensional polymer material prepared by the method provided by the present invention, it is described in conjunction with the accompanying drawings.

[0051] Figure 1 It is a schematic diagram of the topochemical polymerization structure based on discotic liquid crystals of the method of the present invention.

[0052] Figure 2 From the differential scanning calorimetry curve and small-angle X-ray scattering pattern, it can be seen that the discotic liquid crystal monomer based on cyanostyrene prepared in Example 1 forms a hexagonal columnar liquid crystal phase.

[0053] Figure 3 From the changes in the gel permeation chromatography and nuclear magnetic resonance hydrogen spectrum, it can be seen that the topochemical polymerization based on discotic liquid crystals carried out in Example 1 has obtained a one-dimensional polymer material.

[0054] Figure 4 From the nanoindentation mechanical property characterization of the monomer and polymer, it can be seen that the mechanical properties of the one-dimensional polymer material obtained by the topochemical polymerization based on discotic liquid crystals carried out in Example 1 have been greatly improved compared with the monomer.

[0055] Figure 5 From the crystal microscopic image and nuclear magnetic resonance hydrogen spectrum of the monomer after being irradiated with 365 nm ultraviolet light for 24 h in the crystalline state, it can be seen that the discotic liquid crystal monomer based on cyanostyrene prepared in Example 1 does not undergo topochemical polymerization in the crystalline state.

[0056] The present invention describes the preferred embodiments and their effects. However, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0057] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A topochemical polymerization method based on discotic liquid crystals, characterized in that, It includes the following steps: Dissolve 3,4,5-tris(hexyloxy)benzyl cyanide and 1,3,5-benzenetricarbaldehyde in ethanol, add tetrabutylammonium hydroxide, and react at 50 - 60 °C for 1 - 3 h to obtain a discotic liquid crystal monomer; Place the discotic liquid crystal monomer on a substrate, heat it to a temperature ≥ 200 °C to make the discotic liquid crystal monomer in a molten state, then press it to form a film, and then cool it down to 70 - 80 °C, and then irradiate the film sample with ultraviolet light for 12 - 48 h, that is, a one-dimensional polymer material is obtained based on the topochemical polymerization of discotic liquid crystals.

2. The topochemical polymerization method based on discotic liquid crystals according to claim 1, wherein The molar ratio of the 3,4,5-tris(hexyloxy)benzyl cyanide to the 1,3,5-benzenetricarbaldehyde is 2 - 4:

1.

3. The topochemical polymerization method based on discotic liquid crystals according to claim 1, characterized in that, The wavelength of the ultraviolet light is 365 nm.

4. The topochemical polymerization method based on discotic liquid crystals according to claim 1, characterized in that, The structural formula of the discotic liquid crystal monomer is: 。 5. The topochemical polymerization method based on discotic liquid crystals according to claim 1, characterized in that, The 3,4,5-tris(hexyloxy)benzyl cyanide is prepared according to the following steps: Dissolve 5-(bromomethyl)-1,2,3-tris(hexyloxy)benzene, trimethylsilyl cyanide and tetrabutylammonium fluoride in acetonitrile, stir at room temperature for 2 - 4 h, remove the solvent, and then obtain 3,4,5-tris(hexyloxy)benzyl cyanide through extraction and purification; The molar ratio of the 5-(bromomethyl)-1,2,3-tris(hexyloxy)benzene, trimethylsilyl cyanide and tetrabutylammonium fluoride is 1:1 - 2:1 - 2.

6. The topochemical polymerization method based on discotic liquid crystals according to claim 5, characterized in that The 5-(bromomethyl)-1,2,3-tris(hexyloxy)benzene is prepared according to the following steps: React 3,4,5-tris(hexyloxy)benzyl alcohol with phosphorus tribromide in dichloromethane through bromination reaction to obtain 5-(bromomethyl)-1,2,3-tris(hexyloxy)benzene; The molar ratio of the 3,4,5-tris(hexyloxy)benzyl alcohol to the phosphorus tribromide is 1:

1.

7. The topochemical polymerization method based on discotic liquid crystals according to claim 6, wherein The 3,4,5-tris(hexyloxy)benzyl alcohol is prepared according to the following steps: In a nitrogen atmosphere, dissolve methyl gallate, 1-bromohexane, tetrabutylammonium iodide and potassium carbonate in N,N-dimethylformamide, react at 75 - 85 °C for 10 - 24 h, and obtain methyl 3,4,5-tris(hexyloxy)benzoate through extraction and purification; Use lithium aluminum hydride as a reducing agent for the reduction reaction of methyl 3,4,5-tris(hexyloxy)benzoate in a tetrahydrofuran solution to obtain 3,4,5-tris(hexyloxy)benzyl alcohol.

8. According to the topochemical polymerization method based on discotic liquid crystals described in claim 7, characterized in that The molar ratio of the methyl gallate, 1-bromohexane, tetrabutylammonium iodide and potassium carbonate is 1:4:0.01 - 0.05:6 - 8; The molar ratio of the methyl 3,4,5-tris(hexyloxy)benzoate to the lithium aluminum hydride is 1:1 - 2.

9. A one-dimensional polymer material prepared by the topochemical polymerization method based on discotic liquid crystals according to any one of claims 1 - 8.

10. An application of the one-dimensional polymer material described in claim 9 in high-performance liquid crystal polymer materials.

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