Liquid crystal elastomer as well as preparation method and application thereof

Abstract

The invention discloses a liquid crystal elastomer as well as a preparation method and application thereof. The photolatent base is adopted as the catalyst, the strong base catalyst is released under the UV effect, polymerization is conducted through the base catalysis nucleophilic Michael addition mechanism, and due to the fact that the reaction is a click reaction, rapid photocuring 3D printing forming can be achieved. The liquid crystal elastomer network structure is uniform, free groups are not left, low modulus equivalent to thermal polymerization is kept, the driving rate is high, and the liquid crystal elastomer 3D printing system is a novel liquid crystal elastomer 3D printing system and is suitable for intelligent response materials.

Description

Technical Field

[0001] This invention relates to the field of liquid crystal elastomer technology, and in particular to a liquid crystal elastomer, its preparation method, and its application. Background Technology

[0002] Liquid crystal elastomers (LCEs) are a class of smart materials that combine the ordered orientation of liquid crystal molecules with the flexibility of elastomer networks. Traditional LCE fabrication methods (such as molding and stretching alignment) struggle to achieve complex three-dimensional structures and locally programmable actuation, limiting their applications. Digital light processing (DLP) is a photopolymerization-based 3D printing technology that uses ultraviolet (UV) light projection to cure liquid photosensitive resin layer by layer. It offers high printing speed and higher precision (down to the micrometer level), making it suitable for fabricating complex and intricate structures.

[0003] Currently, all photopolymerization 3D printing for LCE utilizes photoinitiated free radical polymerization mechanisms, including double bond self-polymerization and Michael addition reactions between thiol groups and acrylate double bonds. The ink formulations involved are mainly of two types: one is double-bond-terminated liquid crystal oligomers, requiring stepwise oligomer preparation before printing, which is cumbersome and results in high ink viscosity, affecting the accuracy of the printed product and easily causing defects; the other is low-viscosity monomer ink formulations composed of acrylate-terminated liquid crystal monomers, thiol chain extenders, and crosslinking agent monomers. Under free radical conditions, the rapid double bond self-polymerization reaction causes competition between self-polymerization and Michael addition reactions, leading to residual thiol groups in the network and an uneven structure. Furthermore, self-polymerization results in a high crosslinking density and high modulus, limiting the ability to drive deformation.

[0004] Therefore, there is an urgent need to develop a novel 3D printing method for liquid crystal elastomers that can ensure low ink viscosity while maintaining a low material modulus to preserve its driving ability. Summary of the Invention

[0005] The present invention aims to at least partially solve one of the technical problems in the related art.

[0006] Therefore, embodiments of the present invention provide a liquid crystal elastomer, its preparation method, and its application. The preparation method of the liquid crystal elastomer of the present invention aims to ensure low ink viscosity to guarantee product quality while avoiding free radical self-polymerization and maintaining a low material modulus to ensure its driving capability is not impaired.

[0007] In a first aspect, the present invention provides a method for preparing a liquid crystal elastomer, comprising:

[0008] The liquid crystal cell, chain extender, and crosslinking agent are dissolved in the first solvent to form a monomer solution;

[0009] The photocatalyst, photosensitizer, and free radical quencher are dissolved in a second solvent, and then mixed with the monomer solution to obtain 3D printing ink;

[0010] The 3D printing ink is extruded into a mold and reacted in the presence of ultraviolet light to obtain the liquid crystal elastomer.

[0011] 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.

[0012] Further, the chain extender is a thiol-containing compound, preferably a compound containing two or more thiol groups, more preferably one or more of the following: 2,2'-(1,2-ethylenedioxy)bis(ethanedioxide), 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.

[0013] 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) ester, pentaerythritol tetramercaptoacetate ester, trimethylolpropane tris(mercaptoacetic acid), (mercaptopropyl)methylsiloxane homopolymer, 1,2,4,5-phenyltetramercapto, and inositol hexa(mercaptopropionate).

[0014] Furthermore, the photocatalyst includes one or more of TPB-TMG, TPB-TBD, and TPB-DBU.

[0015] Furthermore, the photosensitizer includes one or more of isopropyl-9H-thioxanthone, 2-chlorothioanthrone, 2,4-diethylthioxanthone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0016] Furthermore, the free radical quencher includes one or more of 2,2,6,6-tetramethylpiperidine oxide, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxygen radical (TEMPOL), 2,2,5,5-tetramethylpyrrolidine-1-oxygen radical (PROXYL), and 2,6-di-tert-butyl-4-methylphenol (BHT).

[0017] Furthermore, the first solvent includes one or more of dichloromethane, N,N-dimethylamide, trichloromethane, and tetrahydrofuran.

[0018] Furthermore, the second solvent includes one or more of N,N-dimethylamide, acetone, methanol, and acetonitrile.

[0019] Secondly, the present invention provides a liquid crystal elastomer prepared by the method proposed in the first aspect above.

[0020] Thirdly, the present invention proposes the application of liquid crystal elastomers prepared by the method proposed in the first aspect or the liquid crystal elastomers proposed in the second aspect in smart responsive materials.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] This invention employs a novel photoinitiation system to print liquid crystal elastomers with low modulus and uniform structure without altering the original low-viscosity monomer formulation. This expands the 3D printing method for liquid crystal elastomers and broadens the application fields of 3D printed liquid crystal elastomers.

[0023] This invention uses photocatalyst as a catalyst, which releases a strong base catalyst under UV irradiation and polymerizes through a base-catalyzed nucleophilic Michael addition mechanism. Since this reaction is a click reaction, it can achieve rapid photopolymerization 3D printing.

[0024] The liquid crystal elastomer of this invention has a uniform network structure with no remaining free groups, and maintains a low modulus comparable to thermal polymerization, exhibiting a high driving rate. It is a novel liquid crystal elastomer 3D printing system suitable for smart responsive materials. Attached Figure Description

[0025] 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:

[0026] Figure 1This is a schematic diagram of the synthesis route of the liquid crystal elastomer of the present invention;

[0027] Figure 2 This is a schematic diagram of the liquid crystal elastomer component of the present invention;

[0028] Figure 3 Infrared spectra of the liquid crystal elastomer samples and ink formulations prepared in Example 1, Comparative Example 1, and Comparative Example 3;

[0029] Figure 4 The tensile properties test diagrams are of the liquid crystal elastomer samples prepared in Example 1 and Comparative Examples 1 to 3.

[0030] Figure 5 The driving rate test diagrams are for the liquid crystal elastomer samples prepared in Example 1 and Comparative Examples 1 to 3.

[0031] Figure 6 The images show the viscosity test results of the 3D printing inks in Example 1, Comparative Example 1, and Comparative Example 2. Detailed Implementation

[0032] 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.

[0033] The following description, in conjunction with the accompanying drawings, describes the liquid crystal elastomer proposed in this invention, its preparation method, and the preparation method of the liquid crystal elastomer, including:

[0034] (1) Dissolve the liquid crystal cell, chain extender, and crosslinking agent in the first solvent to form a monomer solution;

[0035] (2) Dissolve the photocatalyst, photosensitizer, and free radical quencher in a second solvent, and then mix them with the monomer solution to obtain 3D printing ink;

[0036] (3) The 3D printing ink is extruded into a mold and reacted in the presence of ultraviolet light to obtain the liquid crystal elastomer.

[0037] The liquid crystal unit in step (1) 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- One or more of the following: 3,6-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.

[0038] In some embodiments, the chain extender is a thiol-containing compound, preferably a compound containing two or more thiol groups, more preferably one or more of the following: 2,2'-(1,2-ethylenedioxy)bis(ethanedioxide), 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.

[0039] 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), pentaerythritol tetramercaptoacetate, trimethylolpropane tris(mercaptoacetic acid), (mercaptopropyl)methylsiloxane homopolymer, 1,2,4,5-phenyltetramercapto, and inositol hexa(mercaptopropionate).

[0040] In some embodiments, the first solvent includes one or more of dichloromethane, N,N-dimethylamide, trichloromethane, and tetrahydrofuran.

[0041] In step (2), in some embodiments, the photocatalyst includes one or more of TPB-TMG, TPB-TBD, and TPB-DBU, wherein TPB-TMG is a photocatalyst prepared using sodium tetraphenylborate and tetramethylguanidine, TPB-TBD is a photocatalyst prepared using sodium tetraphenylborate and 1,5,7-triazabicyclo[4.4.0]decen-5-ene, and TPB-DBU is a photocatalyst prepared using sodium tetraphenylborate and 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0042] In some embodiments, the photosensitizer includes one or more of isopropyl-9H-thioxanthone, 2-chlorothioanthrone, 2,4-diethylthioxanthone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0043] In some embodiments, the free radical quencher comprises one or more of 2,2,6,6-tetramethylpiperidine oxide, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxo radical (TEMPOL), 2,2,5,5-tetramethylpyrrolidine-1-oxo radical (PROXYL), and 2,6-di-tert-butyl-4-methylphenol (BHT). The free radical quencher is used to capture free radicals generated by the photosensitizer, preventing free radicals from initiating side reactions such as acrylate self-polymerization.

[0044] In some embodiments, the second solvent includes one or more of N,N-dimethylamide, acetone, methanol, and acetonitrile.

[0045] In some embodiments, the ultraviolet light source has a wavelength of 385 nm and an optical power density of 15 mW / cm². 2 Ultraviolet light.

[0046] The liquid crystal elastomer of the present invention is prepared by the method of the present invention. The liquid crystal elastomer of the present invention is applied to smart responsive materials.

[0047] The method for preparing liquid crystal elastomers in this invention solves the problems in traditional photopolymer 3D printing where high viscosity of oligomeric inks affects product quality, and the problems of uneven network structure, high modulus, and limited deformation caused by self-polymerization competition of monomer inks.

[0048] The present invention will now be described in detail with reference to specific embodiments.

[0049] Example 1

[0050] Preparation of the photocatalyst TPB-TMG: 10 mmol of tetramethylguanidine (TMG) was mixed with 10 mL of 1 mol / L hydrochloric acid, and 11 mmol of sodium tetraphenylborate (NaBPh4) was dissolved in water and stirred until completely dissolved. The sodium tetraphenylborate aqueous solution was slowly added dropwise to the tetramethylguanidine hydrochloric acid solution, forming a white salt precipitate. After filtration, the precipitate was thoroughly washed with distilled water and methanol, and finally recrystallized with a 4:1 (v / v) mixture of methanol and chloroform. The precipitate was then filtered and dried under vacuum at 40 °C to obtain the photocatalyst TPB-TMG.

[0051] Preparation of liquid crystal elastomers:

[0052] According to such Figure 1 The route shown involves dissolving 5 mmol RM257 (1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene), 4 mmol EDDET (2,2'-(1,2-ethylenedioxy)bis(ethyl mercaptan), and 0.25 mmol PETMP (pentaerythritol tetrakis(3-mercaptopropionic acid) ester) in 5 ml toluene at 40 °C to form a monomer solution.

[0053] 0.0379 g of photocatalyst TPB-TMG, 0.0190 g of photosensitizer ITX (isopropyl-9H-thioxanth-9-one), and 0.0190 g of free radical quencher TEMPO (2,2,6,6-tetramethylpiperidine oxide) were dissolved in 500 μL of DMF (N,N-dimethylamide) and mixed with the above monomer solution to obtain a novel liquid crystal elastomer 3D printing ink.

[0054] The ink was extruded into a quartz glass plate mold measuring 80mm × 80mm × 0.4mm, and the light was applied at a wavelength of 385nm and a power density of 15mW / cm². 2 Irradiation under ultraviolet light for 100s yields a cross-linked film, which is then dried at 60℃ for 24h to obtain a liquid crystal elastomer sample prepared by the novel liquid crystal elastomer 3D printing method.

[0055] The ink was placed in a DLP printer, with the layer thickness set to 80μm, the bottom layer exposure time to 120s, and the single layer exposure time to 100s. The printer parameters were: wavelength 385nm and optical power density 15mW / cm². 2 The novel liquid crystal elastomer 3D printing method was used to obtain liquid crystal elastomer components, such as... Figure 2 As shown, the method of the present invention can 3D print elastomeric components with complex structures.

[0056] Comparative Example 1

[0057] Preparation of control group liquid crystal elastomer samples by free radical polymerization 3D printing method:

[0058] Monomer formulation: 5 mmol RM257 (1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene), 4 mmol EDDET (2,2'-(1,2-ethylenedioxy)diethylthiol), 0.25 mmol PETMP (pentaerythritol tetrakis(3-mercaptopropionic acid) ester), and 0.0379 g free radical photoinitiator DMPA (benzoin dimethyl ether) were dissolved in 5 ml toluene solvent at 40 °C to obtain a low-viscosity ink formulation for the free radical polymerization 3D printing method.

[0059] The ink was extruded into a quartz glass plate mold measuring 80mm × 80mm × 0.4mm, and the light was applied at a wavelength of 385nm and a power density of 15mW / cm². 2 Irradiation under ultraviolet light for 100s yields a cross-linked film, which is then dried at 60℃ for 24h to obtain a liquid crystal elastomer sample prepared by a free radical 3D printing method with monomer formulation.

[0060] Comparative Example 2

[0061] Oligopolymer formulation: First, double-bond-terminated liquid crystal oligomers were prepared by adding 0.0734 g of triethylamine catalyst to 5 mmol RM257 (1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene) and 4 mmol EDDET (2,2'-(1,2-ethylenedioxy)bis(ethyl mercaptan). The reaction was carried out at room temperature for 48 h to obtain a crude product. The crude product was precipitated and washed three times in methanol solution and dried at 40 °C for 48 h to obtain acrylate double-bond-terminated liquid crystal oligomers.

[0062] The ink formulation was obtained by dissolving 1 mmol of liquid crystal oligomer and 0.0367 g of free radical photoinitiator DMPA (benzoin dimethyl ether) in 4 ml of toluene.

[0063] The ink was extruded into a quartz glass plate mold measuring 80mm × 80mm × 0.4mm, and the light was applied at a wavelength of 385nm and a power density of 15mW / cm². 2 Irradiation under ultraviolet light for 100s yields a cross-linked film, which is then dried at 60℃ for 24h to obtain a liquid crystal elastomer sample prepared by the free radical 3D printing method with oligomeric formulation.

[0064] Comparative Example 3

[0065] Preparation of control group liquid crystal elastomer samples by alkali-catalyzed thermal polymerization:

[0066] 5 mmol RM257 (1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene), 4 mmol EDDET (2,2'-(1,2-ethylenedioxy)bis(ethyl mercapto) mercapto), 0.25 mmol PETMP (pentaerythritol tetrakis(3-mercaptopropionic acid) ester), and 0.0379 g catalyst DPA (dipropylamine) were dissolved in 20 mL dichloromethane solvent. After reacting at room temperature for 24 h, a cross-linked film was obtained. The film was then dried at 60 °C for 24 h to obtain a control group liquid crystal elastomer sample prepared by alkali-catalyzed thermal polymerization.

[0067] Experimental Example 1

[0068] Infrared spectroscopy was performed on the monomer formulation-photocatalytic alkali sample prepared in Example 1, the monomer formulation-free radical sample prepared in Comparative Example 1, the monomer formulation-alkali catalytic sample prepared in Comparative Example 3, and the ink formulation. The test results are as follows: Figure 3 As shown. Here, ink refers to the liquid mixture before photolithography without a catalyst. The ink formulations of Example 1, Comparative Example 1, and Comparative Example 3 all contain RM257, EDDET, and PETMP, so the same ink formulation is used instead.

[0069] according to Figure 3 It can be seen that the liquid crystal elastomer samples obtained from the formulations of Example 1, Comparative Example 1, and Comparative Example 3 have a viscosity of 1635 cm⁻¹. -1 The characteristic peaks corresponding to the double bonds of acrylates all disappeared, indicating that the double bonds in each formulation reacted completely. As for 2570 cm⁻¹... -1 The characteristic peaks corresponding to thiol groups show that only the thiol reaction is complete through the base catalysis mechanism (Example 1 and Comparative Example 3), while there are residual thiol groups in Comparative Example 1. This indicates that for formulations containing both acrylate double bonds and thiol groups, the free radical polymerization mechanism will result in residual thiol groups due to self-polymerization competition, leading to an uneven network structure.

[0070] Experimental Example 2

[0071] Tensile properties were tested on the monomer formulation-light-latent alkali sample prepared in Example 1, the monomer formulation-free radical sample prepared in Comparative Example 1, the oligomer formulation-free radical sample prepared in Comparative Example 2, and the monomer formulation-alkali catalytic sample prepared in Comparative Example 3. The test results are as follows: Figure 4 As shown.

[0072] Test Method: The tensile strength of liquid crystal elastomer samples was tested according to GB / T 528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber" and GB / T 1040.1-2025 "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 specimen until fracture, and the maximum stress and strain at fracture were recorded. The tensile strength and elongation at break were calculated.

[0073] according to Figure 4 It can be seen that the liquid crystal elastomer samples of Comparative Examples 1 and 2 have higher moduli than those of Examples 1 and 3, and are more prone to breakage, while the liquid crystal elastomers of Examples 1 and 3 maintain lower moduli and better tensile strength. Therefore, the liquid crystal elastomer prepared by the method of the present invention has the same properties as the liquid crystal elastomer prepared by alkali catalysis.

[0074] Experimental Example 3

[0075] The driving rate of the liquid crystal elastomer samples prepared in Example 1 and Comparative Examples 1-3 was tested, and the test results are as follows: Figure 5 As shown.

[0076] The test method is as follows: under the same conditions, programming is performed, 80% pre-strain is applied to the sample with residual solvent, both ends are fixed, and the sample is vacuum heated at 60℃ until it is completely dry to obtain single-domain samples. The driving rate of each single-domain sample is tested using a dynamic thermomechanical analyzer. Under constant stress mode, a small stress of 10 kPa is applied to the sample, and the strain change of the sample from -10℃ to 140℃ is recorded.

[0077] according to Figure 5 It can be seen that the maximum driving rate of the liquid crystal elastomers prepared in Comparative Examples 1 and 2 is 70% or less, while the maximum driving rate of the liquid crystal elastomer prepared by the novel photocatalytic alkali 3D printing method in Example 1 exceeds 100%, which is similar to the driving rate of the strip obtained by the alkali-catalyzed thermal polymerization method in Comparative Example 3. This indicates that the novel photocatalytic alkali liquid crystal elastomer 3D printing method does not weaken the driving deformation ability of the sample.

[0078] Test Example 4

[0079] Viscosity tests were conducted on the 3D printing inks used in Example 1, Comparative Example 1, and Comparative Example 2. The test results are as follows: Figure 6 As shown.

[0080] The test method is as follows: referring to GB / T 22235-2008 "Determination of viscosity of liquid", the viscosity of 3D printing ink is tested by rheometer under steady-state shear mode, and the viscosity is measured as a function of shear rate (0.01-100 rad / s).

[0081] according to Figure 6 It can be seen that the 3D printing ink in Example 1 has the same low viscosity advantage as Comparative Example 1, while the oligomer formulation in Comparative Example 2 has a higher viscosity.

[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 liquid crystal elastomer, characterized in that, include: The liquid crystal cell, chain extender, and crosslinking agent are dissolved in the first solvent to form a monomer solution; The photocatalyst, photosensitizer, and free radical quencher are dissolved in a second solvent, and then mixed with the monomer solution to obtain 3D printing ink; The 3D printing ink is extruded into a mold and reacted in the presence of ultraviolet light to obtain the liquid crystal elastomer.

2. The method as described in claim 1, 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.

3. The method as described in claim 1, characterized in that, The chain extender is a thiol-containing compound, preferably a compound containing two or more thiol groups, more preferably one or more of the following: 2,2'-(1,2-ethylenedioxy)bis(ethanediol), 2,4-bis(hydrothiomethyl)-1,3,5-trimethylbenzene, thiol-polyethylene glycol-thiol, ethylene glycol dithioacetate, di(thioacetic 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.

4. The method as described in claim 1, characterized in that, 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) ester, pentaerythritol tetramercaptoacetate ester, trimethylolpropane tris(mercaptoacetic acid), (mercaptopropyl)methylsiloxane homopolymer, 1,2,4,5-phenyltetramercapto, and inositol hexa(mercaptopropionate).

5. The method as described in claim 1, characterized in that, The photocatalyst includes one or more of TPB-TMG, TPB-TBD, and TPB-DBU.

6. The method as described in claim 1, characterized in that, The photosensitizer includes one or more of isopropyl-9H-thioxanthone, 2-chlorothioanthrone, 2,4-diethylthioxanthone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

7. The method as described in claim 1, characterized in that, The free radical quencher includes one or more of 2,2,6,6-tetramethylpiperidine oxide, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxygen radical (TEMPOL), 2,2,5,5-tetramethylpyrrolidine-1-oxygen radical (PROXYL), and 2,6-di-tert-butyl-4-methylphenol (BHT).

8. The method as described in claim 1, characterized in that, The first solvent includes one or more of dichloromethane, N,N-dimethylamide, trichloromethane, and tetrahydrofuran; And / or, the second solvent includes one or more of N,N-dimethylamide, acetone, methanol, and acetonitrile.

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

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

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