High-strength and high-toughness liquid crystal elastomer as well as preparation method and application thereof

Abstract

The invention discloses a high-strength and high-toughness liquid crystal elastomer and a preparation method and application thereof.The preparation method of the high-strength and high-toughness liquid crystal elastomer comprises the step that a sulfydryl-terminated liquid crystal oligomer, a rigid chain extender and a cross-linking agent react in the presence of a first catalyst and an optional first solvent, the high-strength and high-toughness liquid crystal elastomer is obtained. According to the high-strength and high-toughness liquid crystal elastomer disclosed by the invention, an effective solution is provided for realizing high strength and high toughness of the liquid crystal elastomer by introducing the rigid chain extender and a polyurethane structure hydrogen bond; the modulus and tensile strength of the liquid crystal elastomer are remarkably improved by a benzene ring rigid structure of the isocyanate-terminated chain extender; the multiplication of the hydrogen bond of the chain extender improves the strength of the material at room temperature on one hand, and on the other hand, the hydrogen bond is used as a sacrifice bond, an additional toughening mechanism is introduced again, and the liquid crystal elastomer has high strength and high toughness under the synergistic effect of multiple factors.

Description

[0001] Cross-references to related applications

[0002] This application is based on and claims priority to Chinese Patent Application No. 202510792484.6, filed on June 13, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of liquid crystal elastomer technology, and in particular to a high-strength, high-toughness liquid crystal elastomer, its preparation method, and its applications. Background Technology

[0004] Liquid crystal elastomers exhibit a wide range of thermomechanical properties due to the unique combination of rubber elasticity and liquid crystal properties, such as soft elasticity and shape-driven behavior. The liquid crystal domain structure is one of the most important factors controlling mechanical behavior and can be classified into single-domain and multi-domain types. Multi-domain liquid crystal elastomers consist of numerous microscopic liquid crystal domains arranged randomly. Under mechanical load, these domains can recombine through domain or mesocrystalline reorientation. Reorientation of liquid crystal domains can significantly improve their toughness under load. However, this unique mechanism for absorbing mechanical energy has not been widely studied and applied.

[0005] Currently, liquid crystal elastomers, widely used in soft robotics, smart materials, and other fields, often have low modulus and strength, and limited tensile strength, limiting their application in industrial production such as vibration damping and mechanical structural materials. Optimizing the chemical structure of the liquid crystal elastomer network can further improve its comprehensive mechanical properties, allowing it to better leverage its mechanical advantages and broaden its application areas. Summary of the Invention

[0006] The present invention aims to at least partially solve one of the technical problems in the related art.

[0007] Therefore, embodiments of the present invention propose a high-strength, high-toughness liquid crystal elastomer, its preparation method, and its application.

[0008] In a first aspect, the present invention proposes a method for preparing a high-strength, high-toughness liquid crystal elastomer, comprising:

[0009] The high-strength, high-toughness liquid crystal elastomer is obtained by reacting a mercapto-terminated liquid crystal oligomer, a rigid chain extender, and a crosslinking agent in the presence of a first catalyst and an optional first solvent.

[0010] Furthermore, the method for preparing the rigid chain extender includes:

[0011] The first polymerization unit and the second polymerization unit are reacted in the presence of a second catalyst and an optional second solvent.

[0012] Furthermore, the first polymerization unit has an isocyanate group, preferably a chain extender having two or more isocyanate groups, and more preferably a chain extender having a diisocyanate group.

[0013] Furthermore, the second polymerization unit is a polyhydroxy compound containing a rigid structure, preferably a polyhydroxy compound containing a benzene ring structure, and more preferably a polyhydroxy compound having a double benzene ring structure.

[0014] Further, the first polymer unit includes one or more of 4,4'-methylenebis(phenyl isocyanate), 4,4-diisocyanate dicyclohexylmethane, hexamethylene diisocyanate, isophorone diisocyanate, and toluene-2,4-diisocyanate.

[0015] Further, the second polymerization unit includes one or more of 1,2-bis(4-hydroxyphenyl)ethane, 3,3-disulfide diphenol, 3,3'-(1E)-1,2-ethylene diphenol, and 4,4'-dihydroxyazobenzene.

[0016] Further, the first catalyst and the second catalyst are each independently selected from one or more of tin-based catalysts and amine catalysts; optionally, the tin-based catalyst includes one or two of dibutyltin dilaurate and stannous octoate; optionally, the amine catalyst includes one or two of triethylamine and dipropylamine.

[0017] Furthermore, the first solvent and the second solvent are organic solvents, each preferably being one or more of tetrahydrofuran, 1,4-dioxane, and N,N-dimethylformamide.

[0018] Furthermore, the method for preparing the thiol-capped liquid crystal oligomer includes reacting a liquid crystal cell and a capping agent in the presence of a third catalyst and optionally a third solvent.

[0019] Further, the liquid crystal unit includes 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene, 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene, (4-(((4-(acryloyloxy)butoxy)carbonyl)oxy)benzoic acid 2-methyl-1,4-diphenol ester, 2-methyl-1,4-phenylene bis(4-(4-(acryloyloxy)butoxy)benzoate), (3R,3AR,6S,6AR)-hexahydrofuran[3,2-B]furan-3, One or more of the following: 6-dimethylbis(4-((acryloyloxy)butoxy)carbonyl)oxy)benzoyl)oxy)benzoate, 4-cyanophenyl 4'-(6-acryloyloxyhexyloxy)benzoate, 4-[[6-[(1-oxo-2-propenyl)oxy]hexyl]oxy]benzoic acid 4-methoxyphenyl ester, 4-[4-[(1-oxo-2-propenyl)oxy]butoxy]benzoic acid biphenyl-4-yl ester, 4-[[6-[(1-oxo-2-propenyl)oxy]hexyl]oxy]benzoic acid 4-ethylphenyl ester.

[0020] Furthermore, the capping agent is a thiol-containing capping agent, preferably a capping agent containing two or more thiol groups, more preferably one or more of the following: 2,2'-(1,2-ethylenedioxy)bis(ethyl)thiol, 2,4-bis(hydrothiomethyl)-1,3,5-trimethylbenzene, thiol-polyethylene glycol-thiol, ethylene glycol dimercaptoacetate, di(mercaptoacetic acid)-1,4-butanediol, bis(3-mercaptopropionic acid)ethylene glycol, bis(2-mercaptoethyl) ether, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, and 1,10-decanedithiol.

[0021] Furthermore, the third catalyst is an amine catalyst, preferably one or more of dipropylamine, triethylamine, and n-hexylamine.

[0022] Furthermore, the third solvent is an organic solvent, preferably one or more of dichloromethane, toluene, N,N-dimethylformamide, and tetrahydrofuran.

[0023] Furthermore, the crosslinking agent is a thiol-containing crosslinking agent, preferably a multi-thiol compound, more preferably one or more of pentaerythritol tetrakis(3-mercaptopropionic acid), trimethylolpropane tris(mercaptoacetic acid), (mercaptopropyl)methylsiloxane homopolymer, 1,2,4,5-benzenetetramercapto, and inositol hexa(mercaptopropionate).

[0024] Secondly, the present invention provides a high-strength, high-toughness liquid crystal elastomer prepared by the method proposed in the first aspect above.

[0025] Thirdly, the present invention proposes the application of the high-strength and high-toughness liquid crystal elastomer prepared by the method proposed in the first aspect above, or the high-strength and high-toughness liquid crystal elastomer proposed in the second aspect above, in smart responsive materials.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] The high-strength and high-toughness liquid crystal elastomer of the present invention utilizes the energy dissipation mechanism of liquid crystal element rotation in the liquid crystal elastomer, and with the help of rigid chain extenders and polyurethane hydrogen sacrificial bonds, improves the strength of the liquid crystal elastomer while further improving its toughness.

[0028] This invention solves the problem of the mutual constraint between strength and toughness in liquid crystal elastomers, and provides a liquid crystal elastomer that combines high strength and high toughness, thus expanding the application of liquid crystal elastomers in the field of high-performance smart response materials.

[0029] The introduction of rigid chain extenders and polyurethane structural hydrogen bonds in the high-strength and high-toughness liquid crystal elastomer of this invention provides an effective solution for achieving high strength and high toughness in liquid crystal elastomers. The rigid benzene ring structure of the isocyanate-terminated chain extender significantly improves the modulus and tensile strength of the liquid crystal elastomer. The multiplication of hydrogen bonds in this chain extender improves the strength of the material at room temperature on the one hand, and on the other hand, as sacrificial bonds, it introduces an additional toughening mechanism. The synergistic effect of multiple factors makes this liquid crystal elastomer possess both high strength and high toughness. Attached Figure Description

[0030] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0031] Figure 1 This is a schematic diagram of the preparation route of the high-strength and high-toughness liquid crystal elastomer in this invention;

[0032] Figure 2 This is a schematic diagram of the preparation route of the rigid chain extender in this invention;

[0033] Figure 3 This is a schematic diagram of the preparation route of the thiol-terminated liquid crystal oligomer in this invention;

[0034] Figure 4 This is a schematic diagram of the phase transition temperature test of the liquid crystal elastomers prepared in Example 1 and Comparative Example 1 of the present invention;

[0035] Figure 5 This is a schematic diagram showing the tensile strength and modulus tests of the liquid crystal elastomers prepared in Examples 1-3 and Comparative Example 1 of the present invention. Detailed Implementation

[0036] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0037] The following description, in conjunction with the accompanying drawings, describes the high-strength, high-toughness liquid crystal elastomer proposed in this invention, its preparation method, and its applications.

[0038] like Figure 1 As shown, the method for preparing the high-strength and high-toughness liquid crystal elastomer of the present invention includes reacting a mercapto-terminated liquid crystal oligomer, a rigid chain extender, and a crosslinking agent in the presence of a first catalyst and optionally a first solvent to obtain the high-strength and high-toughness liquid crystal elastomer.

[0039] In some embodiments, such as Figure 2 As shown, the method for preparing the rigid chain extender includes: reacting a first polymerization unit and a second polymerization unit in the presence of a second catalyst and an optional second solvent.

[0040] In some embodiments, the first polymerization unit has an isocyanate group, preferably a chain extender having two or more isocyanate groups, and more preferably a chain extender having a diisocyanate group.

[0041] In some embodiments, exemplarily, the first polymer has the following structural formula: Figure 2 As shown.

[0042] In some embodiments, the first polymerization unit includes one or more of 4,4'-methylene bis(phenyl isocyanate) (MDI), 4,4-diisocyanate dicyclohexylmethane (HMDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and toluene-2,4-diisocyanate (TDI).

[0043] In some embodiments, the second polymerization unit is a polyhydroxy compound containing a rigid structure, preferably a polyhydroxy compound containing a benzene ring structure, and more preferably a polyhydroxy compound having a double benzene ring structure.

[0044] In some embodiments, exemplarily, the structural formula of the second polymer is as follows: Figure 2 As shown.

[0045] In some embodiments, the second polymerization unit includes one or more of 1,2-bis(4-hydroxyphenyl)ethane, 3,3-disulfide diphenol, 3,3'-(1E)-1,2-ethylenediphenol, and 4,4'-dihydroxyazobenzene.

[0046] In some embodiments, the first catalyst and the second catalyst are each independently selected from one or more of tin-based catalysts and amine catalysts; optionally, the tin-based catalyst includes one or two of dibutyltin dilaurate and stannous octoate; optionally, the amine catalyst includes one or two of triethylamine and dipropylamine.

[0047] In some embodiments, the first solvent and the second solvent are organic solvents, each preferably being one or more of tetrahydrofuran, 1,4-dioxane, and N,N-dimethylformamide.

[0048] In some embodiments, the first polymerization unit is 4,4'-methylenebis(phenyl isocyanate) (MDI), the second polymerization unit is 3,3-disulfide diphenol (PP-OH), the second catalyst is dibutyltin dilaurate (DBTDL), and the second solvent is tetrahydrofuran (THF). 4,4'-methylenebis(phenyl isocyanate) (MDI) is dissolved in tetrahydrofuran (THF), the second catalyst dibutyltin dilaurate (DBTDL) is added, and the tetrahydrofuran (THF) solution of 3,3-disulfide diphenol (PP-OH) is slowly added dropwise at 60°C to react and obtain a rigid isocyanate end-capping chain extender PP containing a benzene ring.

[0049] In some embodiments, such as Figure 3 As shown, the method for preparing the thiol-capped liquid crystal oligomer includes: reacting a liquid crystal cell and a capping agent in the presence of a third catalyst and optionally a third solvent.

[0050] In some embodiments, the liquid crystal unit includes 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene, 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene, (4-(((4-(acryloyloxy)butoxy)carbonyl)oxy)benzoic acid 2-methyl-1,4-diphenol ester, 2-methyl-1,4-phenylene bis(4-(4-(acryloyloxy)butoxy)benzoate), (3R,3AR,6S,6AR)-hexahydrofuran[3,2-B]furan-3, One or more of the following: 6-dimethylbis(4-((acryloyloxy)butoxy)carbonyl)oxy)benzoyl)oxy)benzoate, 4-cyanophenyl 4'-(6-acryloyloxyhexyloxy)benzoate, 4-[[6-[(1-oxo-2-propenyl)oxy]hexyl]oxy]benzoic acid 4-methoxyphenyl ester, 4-[4-[(1-oxo-2-propenyl)oxy]butoxy]benzoic acid biphenyl-4-yl ester, 4-[[6-[(1-oxo-2-propenyl)oxy]hexyl]oxy]benzoic acid 4-ethylphenyl ester.

[0051] In some embodiments, the capping agent is a thiol-containing capping agent, preferably a capping agent containing two or more thiol groups, more preferably one or more of the following: 2,2'-(1,2-ethylenedioxy)bis(ethyl)thiol, 2,4-bis(hydrothiomethyl)-1,3,5-trimethylbenzene, thiol-polyethylene glycol-thiol, ethylene glycol dimercaptoacetate, di(mercaptoacetic acid)-1,4-butanediol, bis(3-mercaptopropionic acid)ethylene glycol, bis(2-mercaptoethyl) ether, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, and 1,10-decanedithiol.

[0052] In some embodiments, the third catalyst is an amine catalyst, preferably one or more of dipropylamine, triethylamine, and n-hexylamine.

[0053] In some embodiments, the third solvent is an organic solvent, preferably one or more of dichloromethane, toluene, N,N-dimethylformamide, and tetrahydrofuran.

[0054] In some embodiments, the liquid crystal unit is 2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)benzoate (RM82), the end-capping agent is 2,2'-(1,2-ethylenedioxy)diethylthiol (EDDET), the third catalyst is dipropylamine, and the third solvent is dichloromethane. 2-methyl-1,4-phenylenebis(4-((6-(acryloyloxy)hexyl)oxy)benzoate (RM82) and 2,2'-(1,2-ethylenedioxy)diethylthiol (EDDET) are dissolved in dichloromethane, and the third catalyst, dipropylamine, is added. The reaction is carried out at room temperature to obtain a crude product. The crude product is precipitated multiple times in a methanol solution and dried to obtain a mercapto-capped liquid crystal oligomer.

[0055] In some embodiments, the crosslinking agent is a thiol-containing crosslinking agent, preferably a polythiol compound, more preferably one or more of pentaerythritol tetrakis(3-mercaptopropionic acid), trimethylolpropane tris(mercaptoacetic acid), (mercaptopropyl)methylsiloxane homopolymer, 1,2,4,5-phenyltetramercapto, and inositol hexa(mercaptopropionate).

[0056] like Figure 1 As shown, the crosslinking agent is a polythiol compound, the first catalyst is dibutyltin dilaurate (DBTDL), the first solvent is tetrahydrofuran (THF), and the rigid chain extender is as follows: Figure 2 The isocyanate-terminated chain extender containing a rigid benzene ring prepared by the route shown is a mercapto-terminated liquid crystal oligomer as follows: Figure 3The thiol-terminated liquid crystal oligomers prepared by the route shown are dissolved in tetrahydrofuran (THF) along with isocyanate chain extenders containing rigid benzene rings and pentaerythritol tetrakis(3-mercaptopropionic acid) (PETMP) crosslinking agent. A catalyst is added and the reaction is carried out at room temperature. After the reaction is completed, the mixture is dried to obtain a high-strength and high-toughness liquid crystal elastomer.

[0057] The high-strength and high-toughness liquid crystal elastomer of the present invention is prepared by the preparation method of the high-strength and high-toughness liquid crystal elastomer of the present invention.

[0058] The present invention will now be described in detail with reference to specific embodiments.

[0059] Example 1

[0060] according to Figure 3 The route shown is for preparing thiol-terminated liquid crystal oligomers. Specifically, 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene (RM257, 6 mmol, 3.53 g) and 2,2'-(1,2-ethylenedioxy)diethylthiol (EDDET, 7 mmol, 1.28 g) were dissolved in 10 mL of dichloromethane. Dipropylamine (2% of the total mass of RM257 and EDDET, 0.096 g) was added as a catalyst, and the reaction was carried out at room temperature for 48 h to obtain the crude product. The crude product was precipitated and washed three times in methanol solution, and dried at 40 °C for 48 h to obtain the thiol-terminated liquid crystal oligomers.

[0061] according to Figure 2 The route shown is for preparing a rigid chain extender. Specifically, taking n=1 as an example, 4,4'-methylenebis(phenyl isocyanate) (MDI, 2 mmol, 0.500 g) is dissolved in 4 mL of ultra-dry tetrahydrofuran (THF), and the catalyst dibutyltin dilaurate (DBTDL, 2% of the total mass of MDI and PP-OH, 0.0143 g) is added. A THF solution (2 mL) of 1,2-bis(4-hydroxyphenyl)ethane (PP-OH, 1 mmol, 0.214 g) is slowly added dropwise under stirring at 60 °C. After reacting for 5 h, an isocyanate-terminated chain extender containing a rigid benzene ring (n=1) is obtained, denoted as 1PP.

[0062] according to Figure 1The route shown is for preparing a high-strength liquid crystal elastomer. Specifically, taking n=1 as an example, a mercapto-terminated liquid crystal oligomer (1 mmol, 4.81 g), a 1PP rigid crosslinking agent (2 mmol, 1.428 g), and a crosslinking agent pentaerythritol tetrakis(3-mercaptopropionic acid) (0.5 mmol, 0.244 g) are dissolved in 20 mL of THF. The catalyst DBTDL is added to 2% (0.130 g) of the total mass. After mixing evenly, the mixture is poured into a 10 cm × 10 cm × 1 cm polytetrafluoroethylene mold and reacted at room temperature for 24 h to form a film. The film is then dried at 80 °C for 48 h to obtain a high-strength and high-toughness liquid crystal elastomer.

[0063] Example 2

[0064] according to Figure 3 The route shown is used to prepare thiol-terminated liquid crystal oligomers. Specifically, 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene (RM257, 6 mmol, 3.53 g) and 2,2'-(1,2-ethylenedioxy)bis(ethyl mercaptan, 7 mmol, 1.28 g) were dissolved in 8 mL of dichloromethane. Dipropylamine (2% of the total mass of RM257 and EDDET, 0.096 g) was added as a catalyst, and the reaction was carried out at room temperature for 24 h to obtain the crude product. The crude product was precipitated and washed three times in methanol solution, and dried at 40 °C for 48 h to obtain the thiol-terminated liquid crystal oligomers.

[0065] according to Figure 2 The route shown is for preparing a rigid chain extender. Specifically, taking n=2 as an example, 4,4'-methylenebis(phenyl isocyanate) (MDI, 3 mmol, 0.750 g) is dissolved in 6 mL of ultra-dry tetrahydrofuran (THF), and the catalyst dibutyltin dilaurate (DBTDL, 2% of the total mass of MDI and PP-OH, 0.0236 g) is added. A THF solution (2 mL) of 1,2-bis(4-hydroxyphenyl)ethane (PP-OH, 2 mmol, 0.428 g) is slowly added dropwise under stirring at 60 °C. After reacting for 5 h, an isocyanate-terminated chain extender containing a rigid benzene ring (n=2) is obtained, denoted as 2PP.

[0066] according to Figure 1The route shown is for preparing a high-strength liquid crystal elastomer. Specifically, taking n=2 as an example, a mercapto-terminated liquid crystal oligomer (1 mmol, 4.81 g), a 2PP rigid crosslinking agent (2 mmol, 2.356 g), and a crosslinking agent pentaerythritol tetrakis(3-mercaptopropionic acid) (0.5 mmol, 0.244 g) are dissolved in 20 mL of THF. The catalyst DBTDL is added to 2% of the total mass (0.1482 g). After mixing evenly, the mixture is poured into a 10 cm × 10 cm × 1 cm polytetrafluoroethylene mold and reacted at room temperature for 24 h to form a film. The film is then dried at 80 °C for 48 h to obtain a high-strength and high-toughness liquid crystal elastomer.

[0067] Example 3

[0068] according to Figure 3 The route shown is used to prepare thiol-terminated liquid crystal oligomers. Specifically, 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene (RM257, 6 mmol, 3.53 g) and 2,2'-(1,2-ethylenedioxy)bis(ethyl mercaptan, 7 mmol, 1.28 g) were dissolved in 8 mL of dichloromethane. Dipropylamine (2% of the total mass of RM257 and EDDET, 0.096 g) was added as a catalyst, and the reaction was carried out at room temperature for 24 h to obtain the crude product. The crude product was precipitated and washed three times in methanol solution, and dried at 40 °C for 48 h to obtain the thiol-terminated liquid crystal oligomers.

[0069] according to Figure 2 The route shown is for preparing a rigid chain extender. Specifically, taking n=3 as an example, 4,4'-methylenebis(phenyl isocyanate) (MDI, 4 mmol, 1.00 g) is dissolved in 6 mL of ultra-dry tetrahydrofuran (THF), and the catalyst dibutyltin dilaurate (DBTDL, 2% of the total mass of MDI and PP-OH, 0.0329 g) is added. A THF solution (2 mL) of 1,2-bis(4-hydroxyphenyl)ethane (PP-OH, 3 mmol, 0.643 g) is slowly added dropwise under stirring at 60 °C. After reacting for 5 h, an isocyanate-terminated chain extender containing a rigid benzene ring (n=3) is obtained, denoted as 3PP.

[0070] according to Figure 1The route shown is used to prepare a high-strength liquid crystal elastomer. Specifically, taking n=3 as an example, a mercapto-terminated liquid crystal oligomer (1 mmol, 4.81 g), a 3PP rigid crosslinking agent (2 mmol, 3.286 g), and a crosslinking agent pentaerythritol tetrakis(3-mercaptopropionic acid) (0.5 mmol, 0.244 g) are dissolved in 20 mL of THF. The catalyst DBTDL is added to 2% of the total mass (0.1668 g). After mixing evenly, the mixture is poured into a 10 cm × 10 cm × 1 cm polytetrafluoroethylene mold and reacted at room temperature for 24 h to form a film. The film is then dried at 80 °C for 48 h to obtain a high-strength and high-toughness liquid crystal elastomer.

[0071] Comparative Example 1

[0072] according to Figure 3 The route shown is used to prepare thiol-terminated liquid crystal oligomers. Specifically, 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene (RM257, 6 mmol, 3.53 g) and 2,2'-(1,2-ethylenedioxy)bis(ethyl mercaptan, 7 mmol, 1.28 g) were dissolved in 8 mL of dichloromethane. Dipropylamine (2% of the total mass of RM257 and EDDET, 0.096 g) was added as a catalyst, and the reaction was carried out at room temperature for 24 h to obtain the crude product. The crude product was precipitated and washed three times in methanol solution, and dried at 40 °C for 48 h to obtain the thiol-terminated liquid crystal oligomers.

[0073] Thiol-terminated liquid crystal oligomer (1 mmol, 4.81 g), MDI (2 mmol, 0.500 g), and crosslinking agent pentaerythritol tetrakis(3-mercaptopropionic acid) (0.5 mmol, 0.244 g) were dissolved in 20 mL of THF. The catalyst DBTDL was added to 2% (0.111 g) of the total mass. After mixing evenly, the mixture was poured into a 10 cm × 10 cm × 1 cm polytetrafluoroethylene mold and reacted at room temperature for 24 h to form a film. The film was then dried at 80 °C for 48 h to obtain a control group liquid crystal elastomer without the second polymerization unit, denoted as OPP.

[0074] Experimental Example 1

[0075] The thermal transition temperatures, including the glass transition temperature (T0), of the liquid crystal elastomers prepared in Example 1 and Comparative Example 1 were tested using the DSC method. g ) and liquid crystal phase transition temperature (T i The test results are as follows: Figure 4 As shown.

[0076] from Figure 4 It can be seen that T g The temperature below room temperature indicates that it is in a highly elastic state, thus preserving the properties of an elastomer. Comparative example: 0PP at T... g The temperature is -14.66℃, Ti The temperature was 72.09℃. With the introduction of a rigid benzene ring, the T of 1PP... g Increased to -7.79℃, T i The temperature decreased to 52.33℃. As the content of rigid benzene rings further increased, T... g Improve, T i decline.

[0077] Experimental Example 2

[0078] The tensile strength, elongation at break, toughness, and modulus of the liquid crystal elastomers prepared in Examples 1-3 and Comparative Example 1 were tested according to GB / T 528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber" and GB / T1040.1-2025 "Determination of Tensile Properties of Plastics Part 1: General Rules". The test specimens were type 2 (20mm × 4mm × 1mm), the ambient temperature was 23±2℃, the humidity was 50±5%, and the tensile rate was 10mm / min. A uniaxial tensile force was applied to the specimens until fracture, and the maximum stress and strain at fracture were recorded. The tensile strength and elongation at break were calculated. The modulus was calculated using the slope of the initial linear segment of the stress-strain curve, and the tensile toughness was calculated using the stress-strain curve integration method. The test results are as follows: Figure 5 As shown, the data is summarized in Table 1.

[0079] Table 1:

[0080]

[0081] Table 1 shows that the tensile strength, elongation at break, and modulus of 1PP liquid crystal elastomer are significantly improved compared to 0PP. This is because the addition of rigid chain extenders increases the MDI content, and both MDI and the benzene rings of PP-OH possess high rigidity. The exponential increase in hydrogen bonds also contributes to the improvement in tensile strength at room temperature. Hydrogen bonds improve strength and can dissociate before covalent bonds, serving as an additional toughening pathway. Increased content of rigid benzene rings leads to decreased tensile strength, elongation, and toughness, but increased modulus. Among these, 1PP exhibits better overall mechanical properties, with a tensile strength of 44.5 MPa, an elongation at break of 934.7%, and a toughness of 170.0 MJ / m. 3 Modulus 11.1 MJ / m 3 .

[0082] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms may refer to different embodiments or examples. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0083] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0084] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for preparing a high-strength, high-toughness liquid crystal elastomer, characterized in that, include: The high-strength, high-toughness liquid crystal elastomer is obtained by reacting a mercapto-terminated liquid crystal oligomer, a rigid chain extender, and a crosslinking agent in the presence of a first catalyst and an optional first solvent.

2. The method as described in claim 1, characterized in that, The method for preparing the rigid chain extender includes: The first polymerization unit and the second polymerization unit are reacted in the presence of a second catalyst and an optional second solvent.

3. The method as described in claim 2, characterized in that, The first polymerization unit has an isocyanate group, preferably a chain extender having two or more isocyanate groups, and more preferably a chain extender having a diisocyanate group; And / or, the second polymerization unit is a polyhydroxy compound containing a rigid structure, preferably a polyhydroxy compound containing a benzene ring structure, and more preferably a polyhydroxy compound having a double benzene ring structure.

4. The method as described in claim 3, characterized in that, The first polymer unit includes one or more of 4,4'-methylenebis(phenyl isocyanate), 4,4-diisocyanate dicyclohexylmethane, hexamethylene diisocyanate, isophorone diisocyanate, and toluene-2,4-diisocyanate. And / or, the second polymer unit comprises one or more of 1,2-bis(4-hydroxyphenyl)ethane, 3,3-disulfide diphenol, 3,3'-(1E)-1,2-ethylene diphenol, and 4,4'-dihydroxyazobenzene; And / or, the first catalyst and the second catalyst are each independently selected from one or more of tin-based catalysts and amine catalysts; optionally, the tin-based catalyst includes one or two of dibutyltin dilaurate and stannous octoate; optionally, the amine catalyst includes one or two of triethylamine and dipropylamine. And / or, the first solvent and the second solvent are organic solvents, each preferably being one or more of tetrahydrofuran, 1,4-dioxane, and N,N-dimethylformamide.

5. The method as described in claim 1, characterized in that, The method for preparing the thiol-capped liquid crystal oligomer includes reacting a liquid crystal cell and a capping agent in the presence of a third catalyst and optionally a third solvent.

6. The method as described in claim 5, characterized in that, The liquid crystal unit includes 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene, 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene, (4-(((4-(acryloyloxy)butoxy)carbonyl)oxy)benzoic acid 2-methyl-1,4-diphenol ester, 2-methyl-1,4-phenylene bis(4-(4-(acryloyloxy)butoxy)benzoate, (3R,3AR,6S,6AR)-hexahydrofuran[3,2-B]furan-3,6-di One or more of the following: 4-((acryloyloxy)butoxy)carbonyl)oxy)benzoyl)oxy)benzoate, 4-cyanophenyl 4'-(6-acryloyloxyhexyloxy)benzoate, 4-[[6-[(1-oxo-2-propenyl)oxy]hexyl]oxy]benzoic acid 4-methoxyphenyl ester, 4-[4-[(1-oxo-2-propenyl)oxy]butoxy]benzoic acid biphenyl-4-yl ester, 4-[[6-[(1-oxo-2-propenyl)oxy]hexyl]oxy]benzoic acid 4-ethylphenyl ester.

7. The method as described in claim 5, characterized in that, The capping agent is a thiol-containing capping agent, preferably a capping agent containing two or more thiol groups, more preferably one or more of the following: 2,2'-(1,2-ethylenedioxy)bis(ethyl)thiol, 2,4-bis(hydrothiomethyl)-1,3,5-trimethylbenzene, thiol-polyethylene glycol-thiol, ethylene glycol dithioacetate, di(thiolacetic acid)-1,4-butanediol, bis(3-mercaptopropionic acid)ethylene glycol, bis(2-mercaptoethyl) ether, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, and 1,10-decanedithiol; And / or, the third catalyst is an amine catalyst, preferably one or more of dipropylamine, triethylamine, and n-hexylamine; and / or, the third solvent is an organic solvent, preferably one or more of dichloromethane, toluene, N,N-dimethylformamide, and tetrahydrofuran.

8. The method as described in claim 1, characterized in that, The crosslinking agent is a thiol-containing crosslinking agent, preferably a polythiol compound, more preferably one or more of pentaerythritol tetrakis(3-mercaptopropionic acid), trimethylolpropane tris(mercaptoacetic acid), (mercaptopropyl)methylsiloxane homopolymer, 1,2,4,5-benzenetetramercapto, and inositol hexa(mercaptopropionate).

9. A high-strength, high-toughness liquid crystal elastomer, characterized in that, Prepared by the method described in any one of claims 1 to 8.

10. The application of the high-strength, high-toughness liquid crystal elastomer prepared by the method according to any one of claims 1 to 8, or the high-strength, high-toughness liquid crystal elastomer according to claim 9, in smart responsive materials.

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