Liquid crystal elastomer material doped with cesium tungsten bronze powder and preparation method thereof

Abstract

This invention discloses a cesium tungsten bronze powder-doped liquid crystal elastomer material and its preparation method, relating to the field of photothermal responsive liquid crystal materials. The liquid crystal elastomer material comprises cesium tungsten bronze nanoparticles with a mass fraction of 1%-20%. The cesium tungsten bronze nanoparticles and acrylate liquid crystal monomers are prepared via a two-step Michael addition method to obtain a liquid crystal elastomer material with a photothermal response deformation of 20%-60%. The liquid crystal elastomer material of this invention exhibits excellent broadband near-infrared photothermal response performance, high photothermal conversion efficiency, reversible deformation performance, and fast response speed.

Description

Technical Field

[0001] This invention relates to the field of photothermal responsive liquid crystal materials technology, specifically to a cesium tungsten bronze powder-doped liquid crystal elastomer material and its preparation method. Background Technology

[0002] Liquid crystal elastomer polymers can respond to external stimuli such as heat, light, electricity, and magnetism, and have received widespread attention in the field of smart materials in recent years. Liquid crystal elastomers with multifunctionality and programmable complex orientations can achieve multiple responses and complex shape changes, showing broad application prospects in soft robotics, artificial muscles, wearable smart fabrics, and other fields.

[0003] Current photoresponsive liquid crystal elastomer materials are divided into photochemically heterogeneous responsive liquid crystal elastomers and photothermally responsive liquid crystal elastomers. Among them, photochemically heterogeneous responsive liquid crystal elastomers are usually responsive to ultraviolet light, which can easily damage human tissue in practical applications, limiting their use in wearable devices and other fields. On the other hand, photothermally responsive liquid crystal elastomers have problems such as low photothermal conversion efficiency, narrow response wavelength range, slow response time, and limited reversible deformation. Summary of the Invention

[0004] One objective of the first aspect of this invention is to provide a cesium tungsten bronze powder-doped liquid crystal elastomer material, which solves the technical problems of low photothermal conversion efficiency, slow response time, and limited reversible deformation in existing liquid crystal elastomer materials.

[0005] Another objective of the first aspect of this invention is to further improve the photothermal conversion efficiency and photothermal response speed of liquid crystal elastomer materials.

[0006] The second objective of this invention is to provide a method for preparing the above-mentioned liquid crystal elastomer material.

[0007] According to a first aspect of the present invention, the present invention provides a cesium tungsten bronze powder-doped liquid crystal elastomer material, the liquid crystal elastomer material comprising cesium tungsten bronze nanoparticles with a mass fraction of any value between 1% and 20%, the cesium tungsten bronze nanoparticles and acrylate liquid crystal monomers being prepared by a two-step Michael addition method to obtain a liquid crystal elastomer material with a photothermal response deformation of any value between 20% and 60%.

[0008] Optionally, the Michael addition two-step method includes a nucleophilic addition reaction, in which the acrylate liquid crystal monomer reacts with a chain extender and a catalyst to prepare a liquid crystal oligomer.

[0009] Optionally, the acrylate liquid crystal monomer is either 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene or 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene.

[0010] Optionally, the chain extender is any one of 3,6-dioxa-1,8-octanedithiol, 2,2-oxybis(ethane-1-thiol), 2,2'-(1,2-ethylenedioxy)bis(ethane-1-thiol), or 2-ethyl-5,11-dioxo-11-[(2-oxotetrahydrothiophene-3-yl)amino]-2-{[(3-mercaptopropionyl)oxy]methyl}-4-oxa-8-thiadecane-1-yl ester.

[0011] Optionally, the catalyst is any one of dipropylamine, n-butylamine, triethylamine, and 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0012] Optionally, the size of the cesium tungsten bronze nanoparticles is any value between 20 nm and 500 nm.

[0013] Optionally, the Michael addition two-step method further includes a crosslinking reaction, in which the cesium tungsten bronze nanoparticles, the liquid crystal oligomer, the acrylate liquid crystal monomer, chain extender, catalyst, crosslinking agent, and photoinitiator are used to prepare the liquid crystal elastomer material through the crosslinking reaction.

[0014] Optionally, the crosslinking agent is any one of pentaerythritol tetra-3-mercaptopropionate, pentaerythritol triacrylate, and polyethylene glycol diacrylate.

[0015] Optionally, the photoinitiator is any one of 2-2-dimethoxy-2-phenylacetophenone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone.

[0016] According to a second aspect of the present invention, the present invention also provides a method for preparing the liquid crystal elastomer material according to any one of the above claims, comprising the following steps:

[0017] Nano-cesium tungsten bronze powder is dispersed in an organic solvent to obtain a nano-cesium tungsten bronze dispersant;

[0018] Liquid crystal oligomers were prepared by dissolving acrylate-based liquid crystal monomers, chain extenders, and catalysts in an organic solvent.

[0019] A liquid crystal precursor solution is prepared by dispersing the nano-cesium tungsten bronze dispersant, the liquid crystal oligomer, the acrylate liquid crystal monomer, the chain extender, the catalyst, the crosslinking agent, and the photoinitiator in an organic solvent.

[0020] Liquid crystal elastomer fibers were obtained by modeling the liquid crystal precursor solution.

[0021] The liquid crystal elastomer fibers were sequentially subjected to uniaxial stretching and ultraviolet curing to prepare a cesium tungsten bronze-doped liquid crystal elastomer material.

[0022] This invention prepares liquid crystal oligomers and liquid crystal precursor solutions sequentially via a two-step Michael addition method. Cesium tungsten bronze nanoparticles, with a mass fraction of 1%-20%, are then doped into the liquid crystal precursor solution to prepare cesium tungsten bronze powder-doped liquid crystal elastomer materials. The liquid crystal elastomer materials prepared in this embodiment exhibit excellent photothermal response performance, photothermal conversion efficiency, and high reversible deformation capability. They can undergo photothermal response deformation under infrared light irradiation and recover their deformation after the infrared light irradiation is removed. Furthermore, the photothermal response deformation of the liquid crystal elastomer is any value between 20% and 60%, making it applicable to fields such as soft robots, artificial muscles, and wearable smart fabrics.

[0023] Furthermore, the size of the cesium tungsten bronze nanoparticles of the present invention is any value between 20nm and 500nm. Cesium tungsten bronze nanoparticles within the above size range have a weaker scattering effect on light, which helps to maintain the high transparency of the liquid crystal elastomer and can more effectively absorb near-infrared rays, improve the photothermal conversion efficiency and photothermal response speed of the liquid crystal elastomer material, and prevent the cesium tungsten bronze nanoparticles from being too large and affecting the elastic properties of the liquid crystal elastomer material.

[0024] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0025] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0026] Figure 1 This is a scanning electron microscope image of a liquid crystal elastomer material according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic flowchart of a method for preparing a liquid crystal elastomer material according to an embodiment of the present invention;

[0028] Figure 3 The deformation of the liquid crystal elastomer material prepared according to Example 1 of the present invention under room temperature and infrared light irradiation conditions;

[0029] Figure 4 The deformation of the liquid crystal elastomer material prepared according to Comparative Example 1 of the present invention under room temperature and infrared light irradiation conditions;

[0030] Figure 5 The deformation of the liquid crystal elastomer material prepared according to Comparative Example 2 of the present invention under room temperature and infrared light irradiation conditions;

[0031] Figure 6 This is a reversible deformation cycle diagram of the liquid crystal elastomer material prepared according to Example 1 of the present invention;

[0032] Figure 7 This is a tensile stress-strain diagram of the liquid crystal elastomer material prepared according to Example 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0033] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0034] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0035] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0036] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0037] Figure 1 This is a scanning electron microscope image of a liquid crystal elastomer material according to an embodiment of the present invention. Figure 2 This is a schematic flowchart of a method for preparing a liquid crystal elastomer material according to an embodiment of the present invention.

[0038] like Figure 1 As shown, this invention provides a cesium tungsten bronze powder-doped liquid crystal elastomer material. The liquid crystal elastomer material comprises cesium tungsten bronze nanoparticles with a mass fraction of 1%-20%. The cesium tungsten bronze nanoparticles and acrylate liquid crystal monomers are prepared via a two-step Michael addition method to obtain a liquid crystal elastomer material with a photothermal response deformation of 40%-60%. Here, the mass fraction of cesium tungsten bronze nanoparticles in the liquid crystal elastomer can be 1%, 2%, 5%, 10%, 15%, or 20%, or any value between 1% and 20%. The photothermal response deformation of the prepared liquid crystal elastomer material in the near-infrared band can be 20%, 30%, 40%, 50%, or 60%, or any value between 20% and 60%.

[0039] In this embodiment, liquid crystal oligomers and liquid crystal precursor solutions are prepared sequentially using a two-step Michael addition method. Cesium tungsten bronze nanoparticles with a mass fraction of 1%-20% are then doped into the liquid crystal precursor solution to prepare a cesium tungsten bronze powder-doped liquid crystal elastomer material. The liquid crystal elastomer material prepared in this embodiment exhibits excellent photothermal response performance, photothermal conversion efficiency, and high reversible deformation capability. It can undergo photothermal response deformation under infrared light irradiation and recover its deformation after the removal of infrared light irradiation. Furthermore, the photothermal response deformation of the liquid crystal elastomer is any value between 20% and 60%, making it applicable to fields such as soft robots, artificial muscles, and wearable smart fabrics.

[0040] In this embodiment, a mass fraction of cesium tungsten bronze nanoparticles in the liquid crystal elastomer material ranging from 1% to 20% maximizes the photothermal conversion efficiency, photothermal response speed, and photothermal reversible deformation of the liquid crystal elastomer material. When the mass fraction of cesium tungsten bronze nanoparticles in the liquid crystal elastomer material is less than 1%, the content of cesium tungsten bronze nanoparticles is too low, which will significantly reduce the photothermal response speed and photothermal conversion efficiency of the liquid crystal elastomer material. When the mass fraction of cesium tungsten bronze nanoparticles in the liquid crystal elastomer material is greater than 20%, the content of cesium tungsten bronze nanoparticles is excessive, resulting in severe agglomeration and a decrease in the optical properties, thermal response deformation properties, and mechanical properties of the liquid crystal elastomer material.

[0041] In a further embodiment, the Michael addition two-step method includes a nucleophilic addition reaction, in which acrylate liquid crystal monomers react with a chain extender and a catalyst to prepare liquid crystal oligomers. In this embodiment, when preparing the liquid crystal elastomer, the liquid crystal oligomers are first prepared by reacting acrylate liquid crystal monomers with a chain extender and a catalyst through a nucleophilic addition reaction. That is, through the nucleophilic addition reaction, the acrylate liquid crystal monomers and the chain extender undergo chemical bonding, realizing the extension and arrangement of the molecular chains. This results in the liquid crystal oligomers having an ordered molecular structure and a high molecular weight before subsequent crosslinking reactions. This helps to form a more uniform and stable liquid crystal structure in the subsequent crosslinking reactions. Furthermore, the high molecular weight of the liquid crystal oligomers can endow the liquid crystal elastomer material with better mechanical properties, thermal stability, and optical properties, thereby improving the photothermal responsiveness and shape memory of the liquid crystal elastomer material.

[0042] In a preferred embodiment, after the acrylate liquid crystal monomer and chain extender are fully dissolved in the nucleophilic addition reaction process, a catalyst is added to carry out the nucleophilic addition reaction, so that the acrylate liquid crystal monomer and chain extender can react completely under the action of the catalyst, thereby improving the resource utilization rate of the acrylate liquid crystal monomer and chain extender and reducing raw material waste.

[0043] In a further embodiment, the acrylate liquid crystal monomer is either 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene or 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene. In this embodiment, both of the above-mentioned acrylate liquid crystal monomers contain acryloyloxy groups, which have good photosensitivity, allowing them to form a compact molecular chain structure under the action of a chain extender, and to rapidly undergo a cross-linking reaction under the action of a photoinitiator, forming a stable liquid crystal network structure, thereby improving the thermal stability and photoresponse capability of the liquid crystal network structure. Furthermore, acrylate liquid crystal monomers exhibit specific liquid crystal phase behavior, capable of forming a stable liquid crystal state within a certain temperature range. By adjusting the structure and ratio of the acrylate monomers, the liquid crystal phase behavior of the liquid crystal elastomer can be precisely controlled.

[0044] In this embodiment, the benzoyloxy and acryloyloxy functional groups in the acrylate liquid crystal monomers can form intermolecular interactions such as hydrogen bonds and van der Waals forces with other components. The presence of these interactions enhances the bonding strength between the liquid crystal elastomer molecular chains, enabling the prepared liquid crystal elastomer material to maintain better elasticity and shape stability when subjected to external forces. In other words, the liquid crystal elastomer material undergoes a certain photothermal response deformation after being irradiated with infrared light, and can recover the deformation after the infrared light is removed, giving the prepared liquid crystal elastomer material high reversible deformation properties.

[0045] In a further embodiment, the chain extender is any one of 3,6-dioxa-1,8-octanedithiol, 2,2-oxybis(ethane-1-thiol), 2,2'-(1,2-ethylenedioxy)bis(ethanedithiol), or 2-ethyl-5,11-dioxo-11-[(2-oxotetrahydrothiophene-3-yl)amino]-2-{[(3-mercaptopropionyl)oxy]methyl}-4-oxa-8-thiadecane-1-yl ester. In this embodiment, the thiol groups and disulfide bonds in the above-mentioned chain extender can enhance the crosslinking degree of the polymer, thereby improving the stability and structural strength of the liquid crystal oligomer. Furthermore, chain extenders containing dioxo structures and complex functional groups can improve the thermal stability, flexibility, and chemical resistance of the liquid crystal oligomer.

[0046] In a further embodiment, the catalyst is any one of dipropylamine, n-butylamine, triethylamine, and 1,8-diazabicyclo[5.4.0]undec-7-ene. In this embodiment, dipropylamine, n-butylamine, and triethylamine can accelerate the nucleophilic addition reaction by lowering the activation energy of the reaction, thereby promoting the formation of liquid crystal oligomers. 1,8-diazabicyclo[5.4.0]undec-7-ene can significantly accelerate the nucleophilic addition reaction, improve the yield and purity of the product, thereby increasing the effective amount of reactants in the subsequent crosslinking reaction and further increasing the yield of liquid crystal elastomer materials.

[0047] In this embodiment, in the preparation of the liquid crystal oligomer, the acrylate liquid crystal monomer is 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene, the chain extender is 3,6-dioxa-1,8-octanedithiol, and the catalyst is dipropylamine, to prepare a liquid crystal oligomer of pentaerythritol tetra-3-mercaptopropionate. The structural formula of pentaerythritol tetra-3-mercaptopropionate is as follows:

[0048]

[0049] In a further embodiment, the size of the cesium tungsten bronze nanoparticles is any value between 20 nm and 500 nm, that is, the size of the cesium tungsten bronze nanoparticles can be 20 nm, 50 nm, 100 nm, 150 nm, 200 nm, 300 nm, 400 nm, or 500 nm, or any value between 20 nm and 500 nm. In this embodiment, the cesium tungsten bronze nanoparticles within the above size range have a weaker light scattering effect, which helps to maintain the high transparency of the liquid crystal elastomer and can more effectively absorb near-infrared light, improving the photothermal conversion efficiency and photothermal response speed of the liquid crystal elastomer material, and preventing the cesium tungsten bronze nanoparticles from being too large and affecting the elastic properties of the liquid crystal elastomer material. Here, the cesium tungsten bronze nanoparticles can be prepared by a solvothermal method or a high-temperature sintering method.

[0050] like Figure 1As shown, in a further embodiment, the Michael addition two-step method also includes a crosslinking reaction. Cesium tungsten bronze nanoparticles, liquid crystal oligomers, acrylate liquid crystal monomers, chain extenders, catalysts, crosslinking agents, and photoinitiators are used to prepare liquid crystal elastomer materials through a crosslinking reaction. In this embodiment, after the acrylate liquid crystal monomers react with the chain extender to form liquid crystal oligomers, the liquid crystal oligomers undergo a crosslinking reaction with the cesium tungsten bronze nanoparticles, acrylate liquid crystal monomers, chain extenders, catalysts, photoinitiators, and crosslinking agents to form a crosslinked network structure. This uniformly disperses the cesium tungsten bronze powder in the gaps of the crosslinked network structure. Furthermore, since a high molecular weight molecular chain structure has already been formed before the crosslinking reaction, it is easier to form a crosslinked network structure during the crosslinking reaction. This helps to avoid increased reaction complexity and byproduct generation due to excessive components in a single reaction step, further improving the purity of the liquid crystal elastomer material.

[0051] In a further embodiment, the crosslinking agent is any one of pentaerythritol tetra-3-mercaptopropionate, pentaerythritol triacrylate, and polyethylene glycol diacrylate. In this embodiment, pentaerythritol tetra-3-mercaptopropionate can be crosslinked with liquid crystal monomers containing carbon-carbon double bonds via a thiol-olefin click chemistry reaction. The crosslinking reaction is controllable and efficient, forming a stable crosslinked network. The prepared liquid crystal elastomer typically exhibits high heat resistance and glass transition temperature. Pentaerythritol triacrylate has multiple acrylate functional groups and can be crosslinked via free radical polymerization. The crosslinked liquid crystal elastomer retains liquid crystal properties while also exhibiting better abrasion resistance and chemical resistance. Polyethylene glycol diacrylate has acrylate functional groups and can be crosslinked via free radical polymerization. The crosslinked liquid crystal elastomer retains liquid crystal properties while also exhibiting better biocompatibility and processability. Here, the crosslinking agent can also be other crosslinking agents that can promote the crosslinking reaction between acrylate liquid crystal monomers and liquid crystal oligomers. The appropriate crosslinking agent can be selected according to the characteristics of the required liquid crystal elastomer material.

[0052] In a further embodiment, the photoinitiator is any one of 2-2-dimethoxy-2-phenylacetophenone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone. In this embodiment, different photoinitiators have different reactivity and absorption wavelengths, enabling them to initiate crosslinking reactions with different degrees of crosslinking. The photoinitiator can be selected based on the specific crosslinking reaction conditions and the desired properties of the prepared liquid crystal elastomer material.

[0053] like Figure 2 As shown, the present invention also provides a method for preparing the liquid crystal elastomer material according to any one of the above claims, comprising the following steps:

[0054] Step S100: Disperse nano-cesium tungsten bronze powder in an organic solvent to obtain nano-cesium tungsten bronze dispersant;

[0055] Step S200: Dissolve acrylate liquid crystal monomers, chain extenders and catalysts in an organic solvent to prepare liquid crystal oligomers;

[0056] Step S300: Disperse nano-cesium tungsten bronze dispersant, liquid crystal oligomer, acrylate liquid crystal monomer, chain extender, catalyst, crosslinking agent and photoinitiator in an organic solvent to prepare a liquid crystal precursor solution;

[0057] Step S400: Model the liquid crystal precursor solution to obtain liquid crystal elastomer fibers;

[0058] Step S500: The liquid crystal elastomer fiber is subjected to uniaxial stretching and UV curing in sequence to prepare a cesium tungsten bronze-doped liquid crystal elastomer material.

[0059] In this embodiment, when preparing the liquid crystal elastomer material, nano-cesium tungsten bronze powder is first dispersed in an organic solvent to obtain a nano-cesium tungsten bronze dispersant. Then, acrylate liquid crystal monomers, chain extenders, and catalysts are dissolved in the organic solvent to prepare liquid crystal oligomers. Next, the nano-cesium tungsten bronze dispersant, liquid crystal oligomers, acrylate liquid crystal monomers, chain extenders, catalysts, crosslinking agents, and photoinitiators are dispersed in an organic solvent to prepare a liquid crystal precursor solution. The liquid crystal precursor solution prepared above is modeled to obtain liquid crystal elastomer fibers. Finally, the liquid crystal elastomer fibers are sequentially subjected to uniaxial stretching and UV curing to prepare a cesium tungsten bronze-doped liquid crystal elastomer material. Here, the organic solvent used to dissolve the cesium tungsten bronze powder is any one of dichloromethane, dimethyl sulfoxide, toluene, N,N-dimethylformamide, and tetrahydrofuran.

[0060] In this embodiment, cesium tungsten bronze nanoparticles are doped into a liquid crystal elastomer material, and a two-step Michael addition method is used in the preparation process. First, a nucleophilic addition reaction is carried out using acrylate liquid crystal monomers, chain extenders, and catalysts to prepare liquid crystal oligomers. Then, the prepared cesium tungsten bronze dispersant is used to prepare a liquid crystal precursor solution through a crosslinking reaction with the liquid crystal oligomers, acrylate liquid crystal monomers, chain extenders, catalysts, crosslinking agents, and photoinitiators. The liquid crystal Zener body solution is then subjected to modeling, uniaxial stretching, and ultraviolet curing to prepare a liquid crystal elastomer material doped with cesium tungsten bronze nanoparticles with a photothermal response deformation of any value between 20% and 60%.

[0061] The present application will be further described in detail below with reference to specific embodiments.

[0062] Example 1

[0063] First, 0.072 g of nano-cesium tungsten bronze powder was dispersed in 2 g of dichloromethane to prepare a cesium tungsten bronze dispersant. Then, 3 g of acrylate liquid crystal monomer 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene RM82 and 0.82 g of chain extender 3,6-dioxa-1,8-octanedithiol were dispersed in 11 g of dichloromethane. After complete dissolution, 0.096 g of catalyst dipropylamine was added, and the mixture was stirred in a water bath at 40 °C for 24 h to prepare a liquid crystal oligomer. Finally, the nano-cesium tungsten bronze dispersant, 1 g of the liquid crystal oligomer, and 0.5 g of acrylate liquid crystal monomer 1,4-bis-[4-(6-acryloyloxy]-2-methylbenzene RM82 were dispersed in 2 g of organic solvent dichloromethane to prepare a cesium tungsten bronze dispersant. [[hexyloxy]benzoyloxy]-2-methylbenzene, 0.01 g of 3,6-dioxa-1,8-octanedithiol, 0.2 g of the crosslinking agent pentaerythritol tetra-3-mercaptopropionate, and 0.02 g of the photoinitiator 2-2-dimethoxy-2-phenylacetophenone were mixed uniformly to prepare a liquid crystal precursor solution. The liquid crystal precursor solution was added to a syringe, and the liquid crystal precursor material was slowly extruded through a nozzle using a syringe pump to prepare liquid crystal elastomer fibers. The liquid crystal elastomer fibers were then uniaxially stretched to 200% of their initial length, and UV curing was used to maintain the orientation of the liquid crystal cells, thus preparing a cesium tungsten bronze-doped liquid crystal elastomer material. In this embodiment, the mass fraction of cesium tungsten bronze nanoparticles in the liquid crystal elastomer material was 4 wt%.

[0064] Example 2

[0065] The difference between Example 2 and Example 1 is that the mass fraction of cesium tungsten bronze nanoparticles is 8 wt%, the acrylate liquid crystal monomer is 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene, the mass of chain extender is 0.93 g, and it is uniaxially stretched to 250% of the initial length.

[0066] Example 3

[0067] The difference between Example 3 and Example 1 is that the mass fraction of cesium tungsten bronze nanoparticles is 16 wt%.

[0068] Example 4

[0069] The difference between Example 4 and Example 5 is that the mass fraction of cesium tungsten bronze nanoparticles is 20 wt%, the catalyst is n-butylamine, and the mass of the catalyst is 0.1 g.

[0070] Comparative Example 1

[0071] The only difference between Comparative Example 1 and Example 1 is that the liquid crystal elastomer material does not contain cesium tungsten bronze nanoparticles.

[0072] Comparative Example 2

[0073] The only difference between Comparative Example 2 and Example 1 is that the mass fraction of cesium tungsten bronze nanoparticles in the liquid crystal elastomer material is 25 wt%.

[0074] First, the photothermal response deformation of the liquid crystal elastomer materials prepared in Examples 1-4 and Comparative Examples 1-2 was tested, and the photothermal response deformation test results of the liquid crystal elastomer materials are shown in Table 1.

[0075] Table 1. Photothermal response deformation results of liquid crystal elastomer materials in Examples 1-4 and Comparative Examples 1-2

[0076] Mass fraction of cesium tungsten bronze nanoparticles Photothermal response deformation Example 1 4wt% 30％ Example 2 8wt% 42％ Example 3 16wt% 55％ Example 4 20wt% 32％ Comparative Example 1 0 0 Comparative Example 2 25wt% 15％

[0077] As shown in Table 1, when the mass fraction of cesium tungsten bronze nanoparticles is any value between 1% and 20%, the photothermal response deformation of the prepared liquid crystal elastomer material is any value between 20% and 60%, indicating that the liquid crystal elastomer material prepared by the present invention has excellent photothermal response speed and photothermal conversion efficiency.

[0078] Figure 3 The deformation of the liquid crystal elastomer material prepared according to Example 1 of the present invention under room temperature and infrared light irradiation conditions is shown. Figure 4 The deformation of the liquid crystal elastomer material prepared according to Comparative Example 1 of the present invention under room temperature and infrared light irradiation conditions is shown. Figure 5 The deformation of the liquid crystal elastomer material prepared according to Comparative Example 2 of the present invention under room temperature and infrared light irradiation conditions is shown. Figure 6 This is a reversible deformation cycle diagram of the liquid crystal elastomer material prepared according to Example 1 of the present invention. Figure 7 This is a tensile stress-strain diagram of the liquid crystal elastomer material prepared according to Example 1 and Comparative Example 1 of the present invention.

[0079] like Figure 3 As shown, the liquid crystal elastomer material prepared in Example 1 has a length of 20 mm at room temperature. After infrared light irradiation, the length of the liquid crystal elastomer material shrinks to 14 mm, and after the infrared light irradiation is removed, it recovers its elastic deformation to 6 mm, indicating that the liquid crystal elastomer material prepared in Example 1 has strong photothermal response performance and reversible deformation performance. Comparative Example 1 (e.g.) Figure 4 (as shown) and Comparative Example 2 (as shown) Figure 5 The deformation of the liquid crystal elastomer material prepared (as shown) before and after infrared irradiation was 0 and 3 mm, respectively, indicating that the photothermal response performance of the liquid crystal elastomer material was poor when the mass fraction of cesium tungsten bronze nanoparticles was less than 1% or more than 20%.

[0080] like Figure 6As shown, the liquid crystal elastomer material prepared in Example 1 exhibits essentially unchanged driving strain after multiple infrared light irradiations and removals, indicating that the liquid crystal elastomer material of the present invention has high reversible deformation performance and can undergo multiple reversible deformations under infrared light irradiation.

[0081] like Figure 7 As shown, the tensile elongation at break of the liquid crystal elastomer material prepared in Example 1 is significantly higher than that in Comparative Example 1, and its shrinkage rate is significantly lower than that in Comparative Example 1, indicating that the liquid crystal elastomer material prepared in Example 1 has stronger elastic deformation properties.

[0082] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0083] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A cesium tungsten bronze powder-doped liquid crystal elastomer material, characterized in that, The liquid crystal elastomer material comprises cesium tungsten bronze nanoparticles with a mass fraction of 1%-20%. The cesium tungsten bronze nanoparticles and acrylate liquid crystal monomers are prepared via a two-step Michael addition method to obtain a liquid crystal elastomer material with a photothermal response deformation of 20%-60%. The preparation method of the liquid crystal elastomer material includes the following steps: Nano-cesium tungsten bronze powder is dispersed in an organic solvent to obtain a nano-cesium tungsten bronze dispersant; Liquid crystal oligomers were prepared by dissolving acrylate-based liquid crystal monomers, chain extenders, and catalysts in an organic solvent. A liquid crystal precursor solution is prepared by dispersing the nano-cesium tungsten bronze dispersant, the liquid crystal oligomer, the acrylate liquid crystal monomer, the chain extender, the catalyst, the crosslinking agent, and the photoinitiator in an organic solvent. Liquid crystal elastomer fibers were obtained by modeling the liquid crystal precursor solution. The liquid crystal elastomer fibers were sequentially subjected to uniaxial stretching and ultraviolet curing to prepare a cesium tungsten bronze-doped liquid crystal elastomer material.

2. The liquid crystal elastomer material according to claim 1, characterized in that, The Michael addition two-step method includes a nucleophilic addition reaction, in which the acrylate liquid crystal monomer, chain extender, and catalyst are reacted to prepare liquid crystal oligomers via the nucleophilic addition reaction.

3. The liquid crystal elastomer material according to claim 2, characterized in that, The acrylate liquid crystal monomer is either 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene or 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene.

4. The liquid crystal elastomer material according to claim 3, characterized in that, The chain extender is any one of 3,6-dioxa-1,8-octanedithiol, 2,2-oxybis(ethane-1-thiol), 2,2'-(1,2-ethylenedioxy)bisethanethiol, and 2-ethyl-5,11-dioxo-11-[(2-oxotetrahydrothiophene-3-yl)amino]-2-{[(3-mercaptopropionyl)oxy]methyl}-4-oxa-8-thiadecane-1-yl ester.

5. The liquid crystal elastomer material according to claim 4, characterized in that, The catalyst is any one of dipropylamine, n-butylamine, triethylamine, or 1,8-diazabicyclo[5.4.0]undec-7-ene.

6. The liquid crystal elastomer material according to any one of claims 1-5, characterized in that, The size of the cesium tungsten bronze nanoparticles is any value between 20 nm and 500 nm.

7. The liquid crystal elastomer material according to claim 6, characterized in that, The Michael addition two-step method also includes a crosslinking reaction, in which the cesium tungsten bronze nanoparticles, the liquid crystal oligomer, the acrylate liquid crystal monomer, chain extender, catalyst, crosslinking agent, and photoinitiator are used to prepare the liquid crystal elastomer material through the crosslinking reaction.

8. The liquid crystal elastomer material according to claim 7, characterized in that, The crosslinking agent is any one of pentaerythritol tetra-3-mercaptopropionate, pentaerythritol triacrylate, and polyethylene glycol diacrylate.

9. The liquid crystal elastomer material according to claim 8, characterized in that, The photoinitiator is any one of 2-2-dimethoxy-2-phenylacetophenone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone.

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