Liquid crystal polymer composite and method for producing the same

Abstract

This invention belongs to the field of organic polymer materials, specifically relating to an improvement on a liquid crystal polymer composite material and its preparation method. The invention uses hydroquinone and benzoic acid as main raw materials to prepare the rigid rings required for liquid crystal molecules. Undecenoic acid is then introduced as a carbon chain, providing the flexible chain required for the liquid crystal molecules. Modified carbon nanotubes are then added to the polymer via in-situ polymerization. Because the defective areas of the modified carbon nanotube walls and both ends are oxidized to form polar groups, they form bonds with the liquid crystal polymer, effectively solving the shortcomings of traditional composite materials, such as insufficient mixing between the matrix and doped phases and easy separation of the two phases during thermal operation.

Description

Technical Field

[0001] This invention belongs to the field of organic polymer materials, specifically relating to an improvement on a liquid crystal polymer composite material and its preparation method. Background Technology

[0002] Liquid crystals are an intermediate phase between solid crystals and liquids, possessing both the fluidity of liquids and the anisotropy of solids, and are considered a special state of matter beyond solids and liquids. The ordered arrangement of liquid crystal molecules directly determines their stability, phase transition laws, electro-optic response, and magneto-optic properties. Liquid crystal polymers, as polymeric materials capable of exhibiting a liquid crystal state, combine the advantages of polymers such as high strength and modulus, high temperature resistance, and chemical stability with the electro-optical and temperature responsiveness of liquid crystals, making them high-performance stimulus-responsive smart materials that occupy an irreplaceable position in high-end manufacturing and special protection fields.

[0003] For example, thermotropic liquid crystal polymer fibers, with their outstanding properties such as high strength and modulus, wear resistance, cut resistance, aging resistance, low moisture absorption, and lightweight, are widely used in special protective equipment, high-temperature dust removal filter materials, high-strength ropes and cables, marine fishery nets and ship cables, and communication cable sheathing and reinforcement. They can be used stably for a long time in harsh environments such as high temperature, corrosion, high humidity, and strong friction, and are a key basic material for high-end equipment and infrastructure.

[0004] In the electronics and electrical fields, liquid crystal polymers, with their low dielectric loss, dimensional stability, and resistance to high-temperature lead-free reflow soldering, have become the preferred materials for high-frequency communication antennas, high-speed connectors, and precision packaging components. In the aerospace and automotive fields, their lightweight and high thermal stability contribute to weight reduction, efficiency improvement, and adaptability to extreme environments. In the medical and chemical fields, their chemical corrosion resistance, low moisture absorption, and biocompatibility meet the stringent requirements of minimally invasive surgical instruments, corrosion-resistant structural components, and separation equipment. Liquid crystal materials, with their anisotropy due to their ordered molecular structure and the processability and mechanical reliability of polymer matrices, have enabled the development of a multi-scenario application system covering information display, communication transmission, special structures, and marine engineering, supporting the upgrading of high-end manufacturing towards high performance, lightweight, and long lifespan.

[0005] Despite the promising applications of liquid crystal polymers, significant technical bottlenecks remain in their molecular design and composite modification processes. Traditional liquid crystal-based composite materials often employ physical blending of the matrix and doped phases, which commonly suffers from uneven dispersion, weak interfacial bonding, easy separation of the two phases during thermal processing, and excessively large phase sizes. This directly leads to fluctuations in mechanical properties, uneven electro-optic response, decreased heat resistance, and shortened service life, making it difficult to meet the demands of high precision and extreme environments. In terms of liquid crystal molecule preparation, conventional routes such as esterification and etherification suffer from drawbacks such as long reaction cycles, numerous byproducts, and insufficient selectivity. Some high-end liquid crystal molecule synthesis routes are lengthy, use expensive raw materials, and require stringent process conditions, resulting in high costs for large-scale production and significant environmental pressure. Furthermore, shortcomings in preparation, such as uneven liquid crystal molecule arrangement, interfacial defects, and residual impurities, can further lead to reduced device response speed, unstable signal transmission, and decreased display and sensing accuracy, hindering the maximization of material performance.

[0006] To address the aforementioned shortcomings, scholars both domestically and internationally have conducted extensive research on improvements, focusing on areas such as interfacial modification of composite systems, in-situ polymerization and synergistic assembly, catalytic system optimization, and precise control of ordered structures. By introducing compatibilizers, designing block copolymers, and employing in-situ photopolymerization and chiral co-assembly strategies, the compatibility and dispersion uniformity of two phases can be improved, and thermal processing phase separation can be suppressed. Novel catalytic systems and green, efficient methods such as click chemistry and supramolecular self-assembly can simplify synthetic routes, improve yield and structural controllability, and reduce preparation costs. Some studies have also optimized the ordered arrangement of liquid crystal molecules through magnetic or electric field-assisted orientation, improving material anisotropy and performance stability. Although current research has achieved phase behavior control, enhanced interfacial bonding, and optimized preparation processes at the laboratory level, issues such as uniformity control, cost control, and batch stability in continuous preparation have not been fully resolved, and performance bottlenecks remain for high-end applications.

[0007] In summary, overcoming the uneven compounding of liquid crystal polymers and defects in the preparation process is urgently needed to improve the overall performance of materials and expand high-end application scenarios. Summary of the Invention

[0008] The purpose of this invention is to provide a liquid crystal polymer composite material and its preparation method.

[0009] To achieve the above-mentioned objectives, the technical solution adopted by this invention is: a method for preparing a liquid crystal polymer composite material, characterized in that the method includes the following steps:

[0010] (1) Synthesis of 4-hydroxyphenylbenzoate, the reaction equation for synthesis is as follows:

[0011] ;

[0012] Synthesis method: Benzoic acid and toluene were added to a reaction vessel. After the benzoic acid dissolved, SOCl2 was added, and the mixture was stirred and heated to 70°C. A mixture of hydroquinone and dichloromethane was added. After the reaction was completed, the pH of the aqueous layer was neutralized. The mixture was washed with water, separated, and the organic layer was recrystallized, filtered, and dried to obtain white crystals, which were the 4-hydroxyphenylbenzoate.

[0013] (2) Synthesis of phenyl 4-(undeca-10-enoyloxy)benzoate. The reaction equation for the synthesis is as follows:

[0014] ;

[0015] Synthesis method: 4-hydroxyphenylbenzoate and dichloromethane were added to a reaction vessel and dissolved. Then, 4-dimethylaminopyridine and undecenoic acid were added and stirred until all solids were completely dissolved. Then, a dichloromethane solution containing N,N-dicyclohexylcarboimide was added and the reaction was stirred with ultrasound at room temperature. When solid substances were observed, the reaction was completed. The mixture was filtered under reduced pressure, and the filtrate was evaporated to crystallize. Recrystallization was then performed to obtain white crystals, which were the 4-(undecanyl-10-enoyloxy)benzoate phenyl ester.

[0016] (3) Preparation of poly(undecyl-10-enoyloxy)benzoic acid phenyl ester composite material, the reaction equation for synthesis is as follows:

[0017] .

[0018] Synthesis method: Multi-walled carbon nanotubes, phenyl 4-(undecad-10-enoyloxy)benzoate and polyvinylpyrrolidone were mixed and ground to obtain a uniformly ground mixture. The mixture was then added to a container containing a mixture of anhydrous ethanol and 1,2-dichloroethane. After ultrasonic treatment, benzoyl peroxide was added, and the mixture was vigorously stirred at 60°C under microwave conditions to obtain the poly(phenyl 4-(undecad-10-enoyloxy)benzoate composite material.

[0019] (4) Injection molding: Set the temperature to 220℃ and the screw speed to 100-300 r / min. The poly(undecyl-10-enoyloxy)benzoic acid phenyl ester composite material prepared in step (3), plasticizer, curing agent, and carbon black are blended in a twin-screw extruder to form a homogeneous melt. The melt is then extruded through a die, cooled, and cut to obtain the injection-molded material. Preferably, the plasticizer is dioctyl cyclohexanedicarboxylate; the curing agent is benzoyl peroxide.

[0020] Accordingly, a liquid crystal polymer composite material prepared using the aforementioned preparation method.

[0021] This invention offers the following advantages: It provides a novel method for preparing liquid crystal polymer composite materials. Specifically, hydroquinone and benzoic acid are used as main raw materials to prepare the rigid rings required for liquid crystal molecules. Undecenoic acid is then introduced as a carbon chain (aspect ratio > 1), providing the flexible chain required for the liquid crystal molecules. Modified carbon nanotubes are then added to the polymer via in-situ polymerization. Because the defective areas of the modified carbon nanotube walls and both ends are oxidized to form polar groups, they form bonds with the liquid crystal polymer, thus solving the shortcomings of traditional composite materials, such as insufficient mixing between the matrix and doped phases and easy separation of the two phases during thermal operation.

[0022] This invention addresses the problems of insufficient blending of the matrix and doped phases, easy separation of physical mixtures, and unstable properties of the composites under high-temperature conditions. In-situ polymerization significantly improves the uniformity of material structure, mechanical stability, and consistency of functional response, ensuring reliable operation even under extreme conditions such as high temperature, strong corrosion, and high load. By constructing an integrated system of "molecular design-ordered assembly-interfacial bonding-process adaptation," this invention achieves the transformation of liquid crystal-based composite materials from physical blending to chemical bonding and from disordered dispersion to ordered orientation. This comprehensively enhances the adaptability of liquid crystal polymers in fields such as high-strength structures, high-frequency communication, special protection, and marine engineering, providing solid support for the independent control of high-end new materials and the high-quality development of strategic emerging industries. Attached Figure Description

[0023] Figure 1 The POM texture diagram of the polymer (without multi-walled carbon nanotubes) prepared in this invention at 260°C;

[0024] Figure 2 The POM texture diagram of the polymer (with added multi-walled carbon nanotubes) prepared in this invention at 260°C. Detailed Implementation

[0025] This invention provides a preparation process for liquid crystal polymer composite materials, specifically including the following steps:

[0026] Synthesis of 1,4-hydroxyphenylbenzoate

[0027] The reaction equation for the synthesis is as follows:

[0028]

[0029] Add 0.1 mol benzoic acid and 150 mL toluene (reaction solvent) to a reaction vessel. After the reactant (benzoic acid) dissolves, add 11 mL of 0.15 mol SOCl2 under an inert gas atmosphere such as nitrogen. Stir and heat to 70°C. Immediately add a mixture of 0.2 mol hydroquinone and 50 mL dichloromethane and react for 20 min. Monitor the reaction until complete. Neutralize the reaction solution with a prepared saturated Na2CO3 solution until the pH of the aqueous layer is neutral. Wash with water 2-3 times, separate the layers, and cool the organic layer with 100 mL of 95% ethanol solution to crystallize. Filter and dry to obtain white crystals, which are the desired 4-hydroxyphenylbenzoate.

[0030] 2. Preparation of phenyl 4-(undecyl-10-enoyloxy)benzoate

[0031] The reaction equation for the preparation is as follows:

[0032]

[0033] 0.1 mol of 4-hydroxyphenylbenzoate was added to a reaction vessel, followed by 100 mL of dichloromethane solution (analytical grade). The mixture was stirred to dissolve, and then 0.1 mol of 4-dimethylaminopyridine (DMAP) and 0.1 mol of undecenoic acid were added. The mixture was ultrasonically stirred until all solids were completely dissolved. Then, a mixed solution of 0.06 mol of N,N-dicyclohexylcarboimide (DCC) and 50 mL of dichloromethane was added. An external drying tube was connected, and the mixture was ultrasonically stirred at room temperature. After observing the appearance of solid substances, the reaction was considered complete. The mixture was then filtered under reduced pressure, and the solvent was evaporated from the filtrate to crystallize the initial product. The initial product was then recrystallized from anhydrous ethanol to obtain white crystals, which were the desired 4-(undecanyl-10-enoyloxy)benzoate.

[0034] 3. Preparation of poly(undecyl-10-enoyloxy)benzoic acid phenyl ester composite material

[0035] The reaction equation for the preparation is as follows:

[0036]

[0037] Multi-walled carbon nanotubes (MWNTs) at a mass ratio of 0.5%–2%, phenyl 4-(undecanyl-10-enoyloxy)benzoate at a mass ratio of 95%–97.5%, and polyvinylpyrrolidone at a mass ratio of 1%–3% were mixed and ground to obtain a homogeneous mixture. This mixture was then added to a container containing anhydrous ethanol / 1,2-dichloroethane (volume ratio 2:1). After ultrasonic treatment for 1 hour, benzoyl peroxide was added, and the mixture was vigorously stirred at 60°C under microwave conditions for approximately 10 minutes. The dynamic viscometer readings showed a yield of 80 Pa·s and a molecular weight of 50,000–120,000, thus optimizing the mechanical properties of the material. This yields the phenyl 4-(undecanyl-10-enoyloxy)benzoate / MWNT composite material. For practical use, injection molding can be performed as needed.

[0038] 4. Product preparation

[0039] This invention provides an optional method for injection molding a composite material, comprising the following steps: setting the temperature to 220°C and the screw speed to 100–300 r / min; blending 65%–83% (by mass) of the composite material prepared in step 3, 15%–30% (by mass) of dioctyl cyclohexanedicarboxylate (plasticizer), 1%–2% (by mass) of benzoyl peroxide (curing agent), and 1%–3% (by mass) of carbon black in a twin-screw extruder for 15–25 minutes. In the molten state, the resin and additives are uniformly mixed through the shearing and mixing action of the twin-screw extruder, forming a homogeneous melt. The molten resin mixture is extruded into strips through a die and cooled by a water tank or cooling belt. Finally, the cooled strips are cut into uniform small granules to obtain the desired plastic granules.

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art, and the data obtained are all average values ​​obtained after at least three repetitions, and each repetition yields valid data.

[0041] Example 1: Preparation of liquid crystal polymer composite material

[0042] Synthesis of 1,4-hydroxyphenylbenzoate

[0043] In a 200 mL three-necked flask equipped with a thermometer and reflux device, 0.1 mol of benzoic acid and 150 mL of toluene were added. After stirring and mixing until the reactants dissolved, 11 mL of 0.15 mol of SOCl2 was added under nitrogen protection. The mixture was stirred and heated to 70 °C. Immediately afterward, a mixture of 0.2 mol of hydroquinone and 50 mL of dichloromethane was added, and the reaction was continued for 20 min. Thin-layer chromatography was used to monitor the reaction. After the reaction was completed (approximately 20 min), the reaction solution was neutralized to a neutral pH with a prepared saturated Na2CO3 solution. The mixture was washed three times with water, separated, and the organic layer was mixed with 100 mL of 95% ethanol solution, cooled, and crystallized. The mixture was filtered, dried, and white crystals were obtained, which were 4-hydroxyphenylbenzoate, with a yield of 85%.

[0044] 2. Preparation of phenyl 4-(undecyl-10-enoyloxy)benzoate

[0045] 0.1 mol of the 4-hydroxyphenylbenzoate synthesized in step 1 was added to a 250 mL single-necked flask, followed by 100 mL of dichloromethane (analytical grade). The mixture was stirred to dissolve the solids. Then, 0.1 mol of 4-dimethylaminopyridine (DMAP) and 0.1 mol of undecenoic acid were added. The mixture was ultrasonically stirred until all solids were completely dissolved. Finally, a mixture containing 0.06 mol of N,N-dicyclohexylcarboimide (DCC) and 50 mL of dichloromethane was added. An external drying tube was connected, and the mixture was ultrasonically stirred at room temperature for 30 min. After the reaction was completed, solid substances were observed to appear. The mixture was then filtered under reduced pressure. The solvent was evaporated from the filtrate, and the solution was crystallized to obtain 25 g of the initial product. The product was recrystallized from anhydrous ethanol to obtain 20 g of white crystals, with a yield of 69%.

[0046] Nuclear magnetic resonance analysis was performed on the white crystalline product: (CDCl3, 400MHz): δ7.21–7.53 (m, 9H, benzene ring hydrogen); δ5.81–5.92 (m, 1H, terminal double bond -CH=); δ4.95–5.04 (m, 2H, double bond =CH2); δ4.23 (t, 2H, -O-CH2-); δ2.52 (t, 2H, -CO-CH2-); δ1.26–1.68 (m, 14H, long-chain alkyl -CH2-). This confirms that the white crystalline product is the desired phenyl 4-(undeca-10-enoyloxy)benzoate.

[0047] 3. Preparation of poly(undecyl-10-enoyloxy)benzoic acid phenyl ester composite material

[0048] 0.35 g of multi-walled carbon nanotubes (MWNTs), 0.1 mol of phenyl 4-(undecad-10-enoyloxy)benzoate, and 0.3 g of polyvinylpyrrolidone were added to a mortar and ground until homogeneous. The mixture was then added to a round-bottom flask containing 150 mL of a mixture of anhydrous ethanol and 1,2-dichloroethane (volume ratio 2:1). The mixture was sonicated at 80 kHz and heated to 20–25 °C for 1 h. Then, 1.50 g of benzoyl peroxide was added, and the mixture was reacted with vigorous stirring at 60 °C for 20 min using a microwave at 2.45 GHz and 200 W. The reaction was considered complete when the dynamic viscometer reading was 80 Pa•s. This yielded a composite material of phenyl 4-(undecad-10-enoyloxy)benzoate and MWNTs.

[0049] Composite material of 4-(undecad-10-enoyloxy)benzoate and multi-walled carbon nanotubes The disappearance of the characteristic hydrogen peaks of the double bond (δ5.81, δ4.95) and the enhancement of the proton peaks of the main chain -CH2- and -CH- (δ1.42-1.85), while the peaks of the benzene ring and ester matrix are retained, further confirming the correct polymer structure. GPC testing shows that the polymer prepared in this step has a number-average molecular weight Mn = 21500, and the molecular weight distribution is as follows: =1.87, uniformly distributed, suitable for subsequent compound modification.

[0050] 4. Preparation of poly(undecyl-10-enoyloxy)benzoate phenyl ester

[0051] Compared to step 3, without the addition of multi-walled carbon nanotubes, 0.1 mol of 4-(undec-10-enoyloxy)benzoate and 0.3 g of polyvinylpyrrolidone were added to a mortar and ground until homogeneous. The mixture was then added to a round-bottom flask containing 150 mL of a mixture of anhydrous ethanol and 1,2-dichloroethane (volume ratio 2:1). The mixture was sonicated at 80 kHz and heated to 20–25 °C for 1 h. Then, 1.50 g of benzoyl peroxide was added, and the reaction was carried out at 60 °C with vigorous stirring for 20 min using a microwave at 2.45 GHz and 200 W. The reaction was considered complete when the dynamic viscometer reading was 80 Pa•s. 4-(undec-10-enoyloxy)benzoate was obtained.

[0052] 5. Product preparation

[0053] The temperature was set to 220℃ and the screw speed to 300 r / min. The composite material prepared in step 3 (74% by mass), plasticizer dioctyl cyclohexanedicarboxylate (20% by mass), curing agent benzoyl peroxide (1% by mass), and carbon black (5% by mass) were mixed in a twin-screw extruder for 15 minutes. The molten resin mixture was extruded into strips through a die and cooled in a water bath. Finally, the cooled strips were cut into uniform small granules to obtain pre-made plastic granules.

[0054] Example 2: Characterization and Analysis of Liquid Crystal Polymer Composite Materials

[0055] 1. Characterization of liquid crystal polymer composite materials

[0056] The polymer prepared in step 3 of Example 1 was characterized by infrared spectroscopy and other methods.

[0057] The infrared spectrum of the polymer prepared in step 3 of Example 1 shows: 3076 cm⁻¹ -1 1632cm -1 The double bond characteristic peaks at 1738 cm⁻¹ are significantly weakened. -1 The ester group peak and benzene ring skeleton peak were retained, while the intensity of the long-chain alkyl peak was enhanced, indicating that the monomer underwent free radical polymerization and the double bond participated in the reaction to form the polymer backbone, thus the target polymer was successfully synthesized.

[0058] The polymer prepared in step 3 of Example 1 1 1H-NMR: The characteristic peaks of double bond hydrogen (δ5.81, δ4.95) disappeared, while the proton peaks of the main chain -CH2- and -CH- (δ1.42-1.85) were enhanced, and the proton peaks of the benzene ring and ester matrix were retained, further confirming the correct polymer structure.

[0059] 2. Liquid crystal texture analysis of liquid crystal polymer composites

[0060] The liquid crystal polymer composite material prepared in Example 1 was subjected to POM observation (polarizing optical microscope observation), GPC test (gel permeation chromatography), DSC analysis (differential scanning calorimetry), TGA analysis (thermogravimetric analysis), and DMA dynamic thermomechanical analysis. The results are as follows.

[0061] (1) POM observation results are as follows Figure 1 , 2As shown. The results indicate that when heated to 260℃, the polymer prepared in step 4 of Example 1 (without multi-walled carbon nanotubes) exhibits a typical nematic liquid crystal schlieren texture, with poor texture uniformity, which easily disappears at high temperatures. The in-situ copolymerization complex of carbon nanotubes and liquid crystal monomers (with added multi-walled carbon nanotubes, corresponding to the product prepared in step 3 of Example 1) maintains a stable nematic texture within the temperature range of 200–322℃. Figure 2 As shown, when heated to 260℃, compared to the polymer prepared in step 4 of Example 1, the polymer prepared in step 3 of Example 1 exhibits a clearer schlieren texture, higher orderliness, and no obvious agglomeration defects. Using carbon nanotube bundles as the center of the flexible polymeric liquid crystal material, the liquid crystal polymers can be well arranged regularly along the core center. Observations during thermal cycling show that the composite of multi-walled carbon nanotubes significantly improves the clarity of the liquid crystal phase during heating and cooling, and the material can still maintain stable internal bonding after melting into the liquid crystal state. This is partly due to the similar thermal expansion coefficients of both, effectively weakening the thermal mismatch effect; on the other hand, the good compatibility between carbon nanotubes and the liquid crystal matrix, coupled with the spontaneous orientation and ordered arrangement ability of the polymeric liquid crystal for carbon nanotubes, jointly promotes the stable construction of the composite system. The multi-walled carbon nanotubes are uniformly dispersed in the matrix without disrupting the ordered arrangement of the liquid crystal, while simultaneously improving texture stability, achieving synergistic optimization of thermal and liquid crystal properties.

[0062] (2) GPC testing showed that the number-average molecular weight Mn of the polymer prepared in step 3 of Example 1 was 21500, and the molecular weight distribution was... =1.87, uniformly distributed, suitable for subsequent compound modification.

[0063] (3) DSC analysis results: The glass transition temperature Tg of the polymer prepared in step 4 of Example 1 is 242℃, the clearing point Ti is 268℃, the liquid crystal phase temperature range is 60℃, and the heat processing window is relatively narrow.

[0064] When the polymer was prepared according to step 3 of Example 1, with 98.5% of the liquid crystal monomer (phenyl 4-(undeca-10-enoyloxy)benzoate) and 1.5% of the multi-walled carbon nanotubes (both by mass), the resulting polymer had a Tg of 208°C, a Ti of 328°C, and a liquid crystal phase temperature range of 86°C, which is 26°C wider than the polymer prepared in step 4 of Example 1. This indicates improved low-temperature processability and retention of high-temperature liquid crystal order. Further increasing the amount of nanoparticles leads to agglomeration, resulting in a narrower liquid crystal phase temperature range, an increased Tg, and decreased processing fluidity.

[0065] The results show that the addition of multi-walled carbon nanotubes in the composite system can reduce the Tg of the liquid crystal polymer, increase Ti, and broaden the liquid crystal phase temperature range; multi-walled carbon nanotubes improve thermal stability and improve fluidity through physical cross-linking and chemical hydrogen bonding.

[0066] (4) TGA analysis: Thermal decomposition temperature (5% weight loss) of the polymer prepared in step 4 of Example 1 =283℃, the thermal stability of the polymer prepared in step 3 of Example 1 first increases and then decreases with increasing multi-walled carbon nanotube dosage. The temperature reached 326℃, an increase of 43℃ compared to the polymer prepared in step 4 of Example 1. This is attributed to the barrier effect of multi-walled carbon nanotubes (MWCNTs) inhibiting the thermal degradation of polymer segments. Simultaneously, the MWCNTs and the liquid crystal matrix form an interpenetrating network, enhancing thermal stability. The polymer prepared in step 3 of Example 1 showed no significant weight loss below 326℃, meeting the requirements for high-temperature processing and use.

[0067] (5) Product DMA+ universal testing machine data

[0068] Dynamic thermomechanical properties (DMA): The plastic granules prepared in step 5 of Example 1 were injection molded and cut into standard rectangular strips (35mm long × 6mm wide × 3mm thick). The storage modulus E′ at room temperature was measured using a dynamic thermomechanical analyzer (DMA) in three-point bending mode, and the result showed that E′ reached 5 GPa.

[0069] Universal testing machine test: The plastic granules prepared in step 5 of Example 1 were injection molded, and the tensile properties were tested according to GB / T 1040-2018; the flexural properties were tested according to GB / T 9341-2008. The results showed that the tensile strength of the plastic granules was 57.5 MPa, the tensile modulus was 3.02 GPa, the elongation at break was 3.96%, the flexural strength was 70.5 MPa, and the flexural modulus was 3.31 GPa.

[0070] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, alterations, substitutions, or variations made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a liquid crystal polymer composite material, characterized in that: The method includes the following steps: (1) Synthesis of 4-hydroxyphenylbenzoate, the reaction equation for synthesis is as follows: ； (2) Synthesis of phenyl 4-(undeca-10-enoyloxy)benzoate. The reaction equation for the synthesis is as follows: ； (3) Preparation of poly(undecyl-10-enoyloxy)benzoic acid phenyl ester composite material, the reaction equation for synthesis is as follows: 。 2. The preparation method according to claim 1, characterized in that: The synthesis method of step (1) includes: adding benzoic acid and toluene to a reaction vessel, waiting for the benzoic acid to dissolve, adding SOCI2, stirring and heating to 70°C, adding a mixture of hydroquinone and dichloromethane, after the reaction is complete, neutralizing the pH of the aqueous layer to neutral, washing with water, separating the liquid, recrystallizing the organic layer, filtering, and drying to obtain the 4-hydroxyphenylbenzoate.

3. The preparation method according to claim 1, characterized in that: The synthesis method of step (2) includes: adding 4-hydroxyphenylbenzoate and dichloromethane to a reaction vessel, dissolving them, then adding 4-dimethylaminopyridine and undecenoic acid, stirring until all solids are completely dissolved, adding a dichloromethane solution containing N,N-dicyclohexylcarboimide, stirring the reaction with ultrasound at room temperature, observing the appearance of solid substances, the reaction is completed, filtering under reduced pressure, evaporating the solvent from the filtrate to crystallize, and then recrystallizing to obtain the 4-(undeca-10-enoyloxy)benzoate phenyl ester.

4. The preparation method according to claim 1, characterized in that: The synthesis method of step (3) includes: mixing and grinding multi-walled carbon nanotubes, phenyl 4-(undecad-10-enoyloxy)benzoate and polyvinylpyrrolidone to obtain a uniformly ground mixture, then adding the mixture to a container containing anhydrous ethanol and 1,2-dichloroethane mixture, ultrasonically treating it, adding benzoyl peroxide, and stirring vigorously at 60°C under microwave conditions to obtain the poly(phenyl 4-(undecad-10-enoyloxy)benzoate composite material.

5. The preparation method according to claim 1, characterized in that: The preparation method further includes step (4), injection molding: the temperature is set to 220℃ and the screw speed is 100~300r / min. The poly(undecyl-10-enoyloxy)benzoic acid phenyl ester composite material prepared in step (3), plasticizer, curing agent and carbon black are blended in a twin-screw extruder to form a homogeneous melt, which is then extruded through a die, cooled and cut to obtain the injection molded material.

6. The preparation method according to claim 5, characterized in that: The plasticizer is dioctyl cyclohexanedicarboxylate.

7. The preparation method according to claim 5, characterized in that: The curing agent is benzoyl peroxide.

8. A liquid crystal polymer composite material prepared by the preparation method according to any one of claims 1 to 7.

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