Liquid crystal elastomer fiber, preparation method thereof and intelligent fabric

Abstract

The invention provides a liquid crystal elastomer fiber, a preparation method thereof and an intelligent fabric, and relates to the technical field of liquid crystal elastomer fibers.The liquid crystal elastomer fiber is prepared from a liquid crystal monomer RM257, a chain extender bis (3-mercaptopropionic acid) ethylene glycol, a cross-linking agent triallyl isocyanurate, an antioxidant, a photoinitiator and a catalyst according to a specific proportion, the liquid crystal monomer RM257 provides an acrylate group, the chain extender provides a thiol group, the cross-linking agent provides vinyl, and the proportion of the acrylate group, the thiol group and the vinyl is regulated by regulating the proportion of the liquid crystal monomer, the chain extender and the cross-linking agent, so that the phase transition temperature of the prepared liquid crystal elastomer prepolymer is influenced, and the phase transition temperature of the prepared liquid crystal elastomer prepolymer is reduced. And finally obtaining the liquid crystal elastomer fiber with lower driving temperature. The driving temperature of the intelligent fabric is low, and the intelligent fabric is suitable for the human body surface.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid crystal elastomer fibers, and more particularly, to a liquid crystal elastomer fiber, a preparation method thereof, and a smart fabric. Background Art

[0002] Liquid crystal elastomer (LCE) is a network structure compound formed by connecting liquid crystal units and adjacent polymer chains, which can exhibit good elasticity in the isotropic phase or the liquid crystal phase. Liquid crystal elastomers have both liquid crystal anisotropy and polymer rubber elasticity. When subjected to external stimuli (heat, light, electricity, magnetism, pH, humidity, etc.), their internal phase state or molecular structure will change, thereby changing the arrangement order of liquid crystal units and causing macroscopic deformation of the composite material itself; when the external stimulus is removed, the liquid crystal elastomer can gradually return to its original shape. At present, using liquid crystal elastomers to prepare smart fabrics has become one of the research hotspots. For example, in the research work in 2019, a related team developed a method for printing and preparing long, soft, and reversibly actuated liquid crystal elastomer fibers (LCE fibers) by direct ink writing technology. Through this method, LCE fibers up to 1.5 m long were obtained. Then, the LCE fibers were processed through processes such as weaving and sewing to obtain various smart fabrics, and the LCE fibers were first applied to smart thermal management clothing. By cutting small holes in the clothes and simply sewing with LCE fibers, the function of opening holes for heat dissipation was initially realized. However, the driving temperature of existing LCE fibers applied to smart fabrics is relatively high (above 80 °C), far higher than the human body temperature, which limits their direct application on the body surface. Summary of the Invention

[0003] The problem to be solved by the present invention is: how to obtain liquid crystal elastomer fibers with a lower driving temperature.

[0004] To solve the above problems, the present invention provides a preparation method of a liquid crystal elastomer fiber, comprising:

[0005] Step S1: Mix a liquid crystal monomer, a chain extender, a crosslinking agent, an antioxidant, a photoinitiator, and a catalyst evenly to obtain a mixture; wherein, the liquid crystal monomer is RM257, the chain extender is ethylene glycol bis(3-mercaptopropionate), and the crosslinking agent is triallyl isocyanurate; the molar ratio of the liquid crystal monomer, the chain extender, and the crosslinking agent is (3 to 3.9):3:0.1;

[0006] Step S2: Stir and react the mixture to obtain a liquid crystal elastomer prepolymer;

[0007] Step S3: Extrude and print the liquid crystal elastomer prepolymer, and then stretch and orient it under ultraviolet light irradiation to obtain a liquid crystal elastomer fiber.

[0008] Optionally, in the step S1, the molar ratio of the liquid crystal monomer, the chain extender and the crosslinking agent is 3.3:3:0.1.

[0009] Optionally, in the step S1, in the mixture, the mass fraction of the antioxidant is 2%, the mass fraction of the photoinitiator is 1.5%, and the mass fraction of the catalyst is 1%.

[0010] Optionally, in the step S1, the antioxidant is 2,6-di-tert-butyl-p-cresol.

[0011] Optionally, in the step S1, the photoinitiator is Irgacure-369.

[0012] Optionally, in the step S1, the catalyst is dipropylamine.

[0013] Optionally, in the step S2, the temperature of the stirring reaction is 75 °C to 85 °C, the rotation speed is 190 rpm to 210 rpm, and the time is 1 h to 2 h.

[0014] The present invention also provides a liquid crystal elastomer fiber, which is made by using the preparation method of the liquid crystal elastomer fiber as described above.

[0015] The present invention also provides an intelligent fabric, which includes the liquid crystal elastomer fiber as described above.

[0016] Optionally, the intelligent fabric further includes nylon or cotton thread.

[0017] Compared with the related art, the present invention uses a liquid crystal monomer RM257, a chain extender bis(3-mercaptopropionic acid) ethylene glycol, a crosslinking agent triallyl isocyanurate, an antioxidant, a photoinitiator and a catalyst with specific ratios to prepare a liquid crystal elastomer fiber. Among them, the liquid crystal monomer RM257 provides acrylate groups, the chain extender provides thiol groups, and the crosslinking agent provides vinyl groups. By adjusting the ratio of the liquid crystal monomer, the chain extender and the crosslinking agent, the ratio of acrylate groups, thiol groups and vinyl groups is further regulated, thereby affecting the phase transition temperature of the prepared liquid crystal elastomer prepolymer, and finally obtaining a liquid crystal elastomer fiber with a lower driving temperature. The intelligent fabric provided by the present invention has a lower driving temperature and is suitable for the human body surface. Description of the Drawings

[0018] Figure 1 It is a schematic flow chart of the preparation method of the liquid crystal elastomer fiber in the embodiment of the present invention;

[0019] Figure 2 It is a schematic structural diagram of the temperature-controlled extrusion 3D printing fiber production device in the embodiment of the present invention;

[0020] Figure 3Schematic diagram of the structure of the intelligent fabric in the embodiment of the present invention;

[0021] Figure 4 Diagram showing the shape change of the intelligent fabric in the heating and cooling processes in the embodiment of the present invention;

[0022] Figure 5 Comparison diagram of the shrinkage conditions of the liquid crystal elastomer fibers prepared in Example 2 when heated to 22°C, 30°C, and 35°C respectively;

[0023] Figure 6 Detection diagram of the thermal driving ability of the intelligent fabric prepared in the application example.

[0024] Explanation of the reference numerals:

[0025] 1, barrel; 2, ultraviolet lamp; 3, roller; 4, liquid crystal elastomer fiber; 5, cotton thread. Detailed implementation manners

[0026] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments described herein. On the contrary, these embodiments are provided to more thoroughly and completely understand the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not used to limit the protection scope of the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the present invention in the specification are only for the purpose of describing specific implementation manners and are not intended to limit the present invention.

[0028] As used herein, the term "comprising" and its variations are open-ended, i.e., "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiment". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts such as "first" and "second" mentioned in the present invention are used to distinguish different objects, rather than to describe a specific order or primary-secondary relationship. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more. It should be noted that the Figure 3 and Figure 4 in the liquid crystal elastomer fiber 4 and the cotton thread 5 are respectively represented by different color curves.

[0029] Aiming at the problems existing in the above related technologies, as Figure 1 shown, an embodiment of the present invention provides a method for preparing a liquid crystal elastomer fiber, comprising:

[0030] Step S1: Mix a liquid crystal monomer, a chain extender, a crosslinking agent, an antioxidant, a photoinitiator and a catalyst evenly to obtain a mixture; wherein, the liquid crystal monomer is RM257, the chain extender is ethylene glycol bis(3-mercaptopropionate), and the crosslinking agent is triallyl isocyanurate; the molar ratio of the liquid crystal monomer, the chain extender and the crosslinking agent is (3 to 3.9):3:0.1;

[0031] Step S2: Stir and react the mixture to obtain a liquid crystal elastomer prepolymer;

[0032] Step S3: Extrude and print the liquid crystal elastomer prepolymer, and then stretch and orient it under ultraviolet light irradiation to obtain a liquid crystal elastomer fiber.

[0033] The present invention prepares a liquid crystal elastomer fiber by using liquid crystal monomers RM257, chain extender ethylene glycol bis(3-mercaptopropionate), crosslinker triallyl isocyanurate, antioxidant, photoinitiator and catalyst in specific ratios. Among them, the liquid crystal monomer RM257 provides acrylate groups, the chain extender provides mercapto groups, and the crosslinker provides vinyl groups. By adjusting the ratios of the liquid crystal monomer, chain extender, and crosslinker, the ratios of acrylate groups, mercapto groups, and vinyl groups are further regulated, thereby affecting the phase transition temperature of the prepared liquid crystal elastomer prepolymer, and finally obtaining a liquid crystal elastomer fiber with a lower driving temperature. The intelligent fabric provided by the present invention has a lower driving temperature and is suitable for the human body surface.

[0034] Specifically, in some embodiments of the present invention, step S3 is implemented by using a temperature-controlled extrusion 3D printing fiber production device, such as Figure 2 shown. This temperature-controlled extrusion 3D printing fiber production device includes a syringe 1, a mechanical pump (not shown in the figure), an ultraviolet lamp 2, and a roller 3. During use, the liquid crystal elastomer prepolymer is poured into the syringe 1, and then the liquid crystal elastomer prepolymer is heated to a suitable extrusion temperature (for example, 80 °C), and then the liquid crystal elastomer prepolymer is extruded through the mechanical pump and stretched and oriented under ultraviolet light irradiation by the roller 3 to obtain the liquid crystal elastomer fiber 4.

[0035] In some embodiments of the present invention, preferably, in step S1, the molar ratio of the liquid crystal monomer, the chain extender, and the crosslinker is 3.3:3:0.1. The phase transition temperature of the liquid crystal elastomer prepolymer prepared in this example is 30 °C, which is closer to the temperature of the human body surface and is more suitable for the human body surface.

[0036] In some embodiments of the present invention, in step S1, in the mixture, the mass fraction of the antioxidant is 2%, the mass fraction of the photoinitiator is 1.5%, and the mass fraction of the catalyst is 1%.

[0037] In some embodiments of the present invention, exemplarily, in step S1, the antioxidant is 2,6-di-tert-butyl-p-cresol, the photoinitiator is Irgacure-369, and the catalyst is dipropylamine.

[0038] In some embodiments of the present invention, in step S2, the temperature of the stirring reaction is 75 °C to 85 °C, the rotation speed is 190 rpm to 210 rpm, and the time is 1 h to 2 h.

[0039] The embodiments of the present invention also provide a liquid crystal elastomer fiber prepared by using the preparation method of the liquid crystal elastomer fiber as described above.

[0040] The embodiments of the present invention also provide an intelligent fabric including the liquid crystal elastomer fiber as described above.

[0041] In some embodiments of the present invention, the smart fabric further includes nylon or cotton thread. Specifically, as Figure 3 shown, the smart fabric includes a common part and a driving part, the common part and the driving part are arranged at intervals, the common part is woven from cotton thread 5, and the driving part is woven from liquid crystal elastomer fiber 4. Figure 4 It is a diagram showing the shape change of the smart fabric during heating and cooling. From Figure 4 it can be seen that since the part composed of liquid crystal elastomer fiber 4 shrinks when heated, while the part composed of cotton thread does not respond to heat stimulation. After the temperature rises, the part composed of liquid crystal elastomer fiber 4 shrinks when heated, while the part composed of cotton thread 5 does not respond to heat stimulation. At this time, pores are generated, and when the temperature drops, the liquid crystal elastomer fiber 4 returns to its original length and the pores disappear.

[0042] The present invention will be further described below with specific embodiments.

[0043] Embodiment 1

[0044] A1. Mix liquid crystal monomer, chain extender, crosslinking agent, antioxidant, photoinitiator and catalyst evenly to obtain a mixture; wherein, the liquid crystal monomer is RM257, the chain extender is ethylene glycol bis(3-mercaptopropionate), the crosslinking agent is triallyl isocyanurate, the antioxidant is 2,6-di-tert-butyl-p-cresol, the photoinitiator is Irgacure-369, and the catalyst is dipropylamine; the molar ratio of the liquid crystal monomer, the chain extender and the crosslinking agent is 3.0:3:0.1; in the mixture, the mass fraction of the antioxidant is 2%, the mass fraction of the photoinitiator is 1.5%, and the mass fraction of the catalyst is 1%.

[0045] A2. Stir and react the mixture to obtain a liquid crystal elastomer prepolymer; wherein, the temperature of the stirring reaction is 80 °C, the rotation speed is 200 rpm, and the time is 1.5 h.

[0046] A3. Pour the liquid crystal elastomer prepolymer into a syringe, then heat the liquid crystal elastomer prepolymer to 80 °C, and then extrude the liquid crystal elastomer prepolymer through a mechanical pump, and stretch and orient it under ultraviolet light irradiation by a roller to obtain the liquid crystal elastomer fiber.

[0047] Embodiment 2

[0048] The difference from Embodiment 1 is that in step A1, the molar ratio of the liquid crystal monomer, the chain extender and the crosslinking agent is 3.3:3:0.1.

[0049] Embodiment 3

[0050] The difference from Example 1 is that in step A1, the molar ratio of the liquid crystal monomer, the chain extender and the crosslinking agent is 3.6:3:0.1.

[0051] Example 4

[0052] The difference from Example 1 is that in step A1, the molar ratio of the liquid crystal monomer, the chain extender and the crosslinking agent is 3.9:3:0.1.

[0053] Comparative Example

[0054] B1. First, place the liquid crystal monomer RM257 in an 85°C oven and heat it until it melts, then add the chain extender n-butylamine and the photoinitiator Irgacure-651 to obtain a mixture; in the mixture, the mass fraction of the liquid crystal monomer RM257 is 92.3%, the mass fraction of the chain extender n-butylamine is 5.7%, and the mass fraction of the photoinitiator is 2.0%.

[0055] B2. Stir and react the mixture to obtain a liquid crystal elastomer prepolymer; among them, the temperature of the stirring reaction is 80°C, the rotation speed is 200 rpm, and the time is 1.5 h.

[0056] B3. Pour the liquid crystal elastomer prepolymer into a syringe, then heat the liquid crystal elastomer prepolymer to 80°C, and then extrude the liquid crystal elastomer prepolymer through a mechanical pump, and stretch and orient it under ultraviolet light irradiation by a roller to obtain the liquid crystal elastomer fiber.

[0057] Application Example

[0058] Use cotton thread and the liquid crystal elastomer fiber prepared in Example 2 to prepare a smart fabric. The smart fabric includes a common part and a driving part, the common part and the driving part are arranged at intervals, the common part is woven by cotton thread 5, and the driving part is woven by liquid crystal elastomer fiber 4.

[0059] Experimental Example

[0060] The detection results of the phase transition temperature of the liquid crystal elastomer prepolymers prepared in Examples 1-4 and the comparative example are shown in Table 1. It can be seen from Table 1 that compared with the comparative example, the phase transition temperature of the liquid crystal elastomer prepolymers prepared in Examples 1-4 is lower, which in turn determines that the driving temperature of the liquid crystal elastomer fibers prepared in Examples 1-4 is lower.

[0061] Table 1

[0062] Sample number Phase change temperature (°C) Example 1 25 Example 2 30 Example 3 35 Example 4 45 Comparative example 100

[0063] Heat the liquid crystal elastomer fiber prepared in Example 2 to 22°C, 30°C, and 35°C respectively, and observe its shrinkage situation. The results are shown in Figure 5 , fromFigure 5 It can be seen that the shrinkage rates of the liquid crystal elastomer fibers prepared in Example 2 at 22 °C, 30 °C, and 35 °C are 0%, 7.69%, and 23% respectively, indicating that the liquid crystal elastomer fibers prepared in Example 2 can be driven at temperatures above 30 °C. It should be noted that Figure 5 In the three pictures from top to bottom, the initial length of the liquid crystal elastomer fibers is 130 mm, and the length in the figure is the actual length of the liquid crystal elastomer fibers when heated to the corresponding temperature.

[0064] The test results of the thermal driving ability of the intelligent fabric prepared in the application example are shown in Figure 6 , from Figure 6 It can be seen that for the intelligent fabric prepared in the application example, obvious shrinkage occurs as the temperature increases. At 100 °C, the shrinkage rate is 16.7%, and at 150 °C, the shrinkage rate is 25.0%. After the external thermal stimulus is removed, the intelligent fabric returns to its original state, with a response time of about 2 s and a recovery time of about 2 s. From the characterization results, it can be seen that after the liquid crystal elastomer fibers prepared in Example 2 are woven into an intelligent fabric, the entire intelligent fabric has good heat shrinkage and recovery properties, proving the feasibility of the intelligent fabric woven from the liquid crystal elastomer fibers provided in the present invention in thermal management.

[0065] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. A method for preparing a liquid crystal elastomer fiber, characterized in that, Including: Step S1: Mix a liquid crystal monomer, a chain extender, a crosslinking agent, an antioxidant, a photoinitiator, and a catalyst uniformly to obtain a mixture; wherein, the liquid crystal monomer is RM257, the chain extender is ethylene glycol bis(3-mercaptopropionate), and the crosslinking agent is triallyl isocyanurate; the molar ratio of the liquid crystal monomer, the chain extender, and the crosslinking agent is (3 to 3.9):3:0.1; Step S2: Stir and react the mixture to obtain a liquid crystal elastomer prepolymer; Step S3: After extruding and printing the liquid crystal elastomer prepolymer, stretch and orient it under ultraviolet light irradiation to obtain liquid crystal elastomer fibers.

2. The preparation method of the liquid crystal elastomer fiber according to claim 1, characterized in that, In step S1, the molar ratio of the liquid crystal monomer, the chain extender, and the crosslinking agent is 3.3:3:0.

1.

3. The preparation method of the liquid crystal elastomer fiber according to claim 1, characterized in that, In step S1, in the mixture, the mass fraction of the antioxidant is 2%, the mass fraction of the photoinitiator is 1.5%, and the mass fraction of the catalyst is 1%.

4. The preparation method of the liquid crystal elastomer fiber according to claim 1, characterized in that, In step S1, the antioxidant is 2,6-di-tert-butyl-p-cresol.

5. The preparation method of the liquid crystal elastomer fiber according to claim 1, wherein In step S1, the photoinitiator is Irgacure-369.

6. The preparation method of the liquid crystal elastomer fiber according to claim 1, wherein, In step S1, the catalyst is dipropylamine.

7. The preparation method of the liquid crystal elastomer fiber according to claim 1, characterized in that In step S2, the temperature of the stirring reaction is 75°C to 85°C, the rotation speed is 190 rpm to 210 rpm, and the time is 1 h to 2 h.

8. A liquid crystal elastomer fiber, characterized in that, Prepared by the method for preparing liquid crystal elastomer fibers according to any one of claims 1 to 7.

9. An intelligent fabric, characterized in that, Including the liquid crystal elastomer fibers according to claim 8.

10. The intelligent fabric according to claim 9, wherein, Also including nylon or cotton thread.

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