Liquid crystal elastomer wrap yarn and preparation method thereof

Abstract

The invention relates to a liquid crystal elastomer wrap yarn and a preparation method thereof, aims to prepare intelligent fibers with high elasticity, high resilience and temperature responsiveness, and is suitable for the fields of intelligent wearing, flexible electronics, environmental response textiles and the like. The method comprises the following steps: dissolving LCE polymer particles in an organic solvent to prepare an LCE solution; the yarn is wrapped through a self-made wrapping device; after curing by an ultraviolet lamp, collecting by a winding device; and finally, drying in a drying oven. The organic solvent is a mixed solvent of N, N-dimethylacetamide and dichloromethane according to the volume ratio of 1: 1, and the best effect is achieved. By optimizing the concentration of the LCE solution and the type of the yarn, the deformation rate of the prepared coated yarn at the fixed temperature of 80 DEG C can reach 8%-10%, and the breaking strength and the elongation at break are both remarkably improved. The invention provides a simple, efficient and extensible preparation method for the development of intelligent materials, and provides a new technical scheme for the fields of intelligent textiles and flexible electronics.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of liquid crystal elastomer composite fibers, and particularly relates to a liquid crystal elastomer covered yarn and a preparation method thereof. Background Art

[0002] With the rapid development of intelligent materials and wearable technologies, the demand for materials that can respond to external stimuli and generate mechanical motion is increasing. Liquid Crystal Elastomers (LCEs), as a kind of intelligent material with unique physical and chemical properties, have received extensive attention because they can achieve large-scale and reversible shape changes under external stimuli. LCEs combine the anisotropy of liquid crystals and the elastic properties of elastomers, and can undergo phase transitions under stimuli such as heat, electricity, magnetism or light, thereby realizing the transition from the nematic phase to the isotropic phase, accompanied by significant dimensional changes and mechanical property alterations.

[0003] However, LCEs face some challenges in practical applications. Firstly, the mechanical strength of LCEs is usually weak, which limits their use in applications that need to bear large loads. Secondly, the driving modes of LCEs mainly focus on shrinkage deformation, lacking diverse driving behaviors. In addition, the preparation and processing methods of LCEs are relatively complex, making it difficult to achieve large-scale production and application.

[0004] To solve these problems, researchers have begun to explore the combination of LCEs with other materials to improve their mechanical properties and driving capabilities. Among them, covering LCEs outside other yarns is an effective strategy. By covering LCEs on high-strength and high-modulus yarns (such as carbon nanotube fibers, metal fibers or high-performance polymer fibers), not only can the mechanical strength of the composite fiber be significantly improved, but also the intelligent response characteristics of LCEs can be utilized to achieve controllable driving and shape changes.

[0005] This composite fiber structure has broad application prospects in the fields of intelligent textiles, soft robots, biomedical devices, etc. For example, in intelligent textiles, the composite fiber can be used to manufacture adaptive clothing that can respond to environmental changes (such as temperature, humidity or light); in soft robots, the composite fiber can be used as artificial muscles to achieve precise motion control and grasping functions; in biomedical devices, the composite fiber can be used to manufacture intelligent scaffolds or drug delivery systems to achieve the response and regulation of the physiological environment.

[0006] Although previous studies have reported methods for compounding LCEs with other materials, there is still a lack of a simple, efficient, and scalable preparation method that can achieve uniform coating of LCEs on other yarns while maintaining their intelligent response characteristics. Therefore, developing a new preparation method for elastic liquid crystal-coated yarns is of great significance for promoting the development of intelligent materials and wearable technologies. Summary of the Invention

[0007] The present invention provides a liquid crystal elastomer-coated yarn and a preparation method thereof, aiming to prepare intelligent fibers with high elasticity, high resilience, and temperature responsiveness, which are applicable to fields such as smart wearables, flexible electronics, and environment-responsive textiles. The technical solution adopted in the present invention is as follows:

[0008] The preparation method of the liquid crystal elastomer-coated yarn includes the following steps:

[0009] 1) Immerse the LCE polymer in an organic solvent and dissolve it by controlling the amount of the added organic solvent to obtain an LCE solution.

[0010] 2) Pass the yarn through the LCE solution so that the LCE solution is coated on the yarn (in some embodiments of the present invention, it is achieved by using a self-made LCE solution coating device), and after coating, it is cured by an ultraviolet lamp; in this step, by changing the type of yarn, different types of LCE-coated yarns can be obtained.

[0011] 3) Wind and collect the cured yarn with a winding roller to obtain the liquid crystal elastomer-coated yarn. In particular, by using the method of the present invention, a liquid crystal elastomer-coated yarn with high elasticity, high resilience, and temperature responsiveness can be obtained, and the method is simple and can be stably produced on a large scale.

[0012] In the above technical solution, further, the organic solvent used in step 1) is a mixed solution of N,N-dimethylacetamide and dichloromethane in a volume ratio of 1:1.

[0013] Further, in step 1), the LCE particles are immersed in the mixed solution at a corresponding concentration of 5% - 20%, and then heated and stirred at 50°C for 4 - 6 hours, observing the state at any time until the LCE particles are completely dissolved. In some embodiments of the present invention, the liquid crystal monomer of the LCE used is RM82, which belongs to a thermotropic liquid crystal elastomer, and its phase state undergoes a reversible transformation with temperature change. The design of the present invention is mainly applied to self-adaptive breathable clothing.

[0014] Further, the yarn in step 2) is a nylon yarn, a polyester-spandex blended yarn, a cotton-spandex blended yarn, a viscose-nylon blended yarn, or silk, and more preferably a pure nylon yarn.

[0015] Further, in step 3), it is cured with an ultraviolet lamp before winding and collecting, and then put into an ultraviolet lamp box for ultraviolet lamp curing for 5 minutes after winding.

[0016] Further, after photo-curing in step 3), it is put into an oven for drying at a temperature of 60 °C for 30 minutes.

[0017] Due to the above technical solutions, the present invention has the following beneficial effects:

[0018] 1) In the present invention, the LCE particles are dissolved in a mixed solution of N, N-dimethylacetamide and dichloromethane in a volume ratio of 1:1 as the solvent, and the effect is the best. Appropriately increasing the temperature helps to accelerate the dissolution of the particles.

[0019] 2) When selecting the yarn for preparing the LCE-coated yarn, the roughness, thickness, and elasticity of the yarn itself need to be considered. For overly smooth yarns and relatively thick yarns, it is not conducive to the adhesion of the LCE solution. For yarns with too low elongation at break, brittle fracture is likely to occur. After the LCE is coated, the temperature-responsive performance of the LCE is difficult to take effect. In the present invention, nylon yarn is preferably used.

[0020] 3) When the LCE concentration is in the range of 5% - 20%, the higher the concentration, the mechanical properties are gradually improved and enhanced. With the increase of the concentration, the coating effect is better, and the temperature responsiveness of the LCE is gradually improved.

[0021] 4) At a fixed temperature (80 °C), the best deformation rate of the coated yarn obtained in the present invention can reach 8% - 10%, showing the characteristic of small deformation at a certain temperature. This small deformation meets the wearing requirements of environmentally responsive textiles. According to the literature and wearing standards, the elasticity of wearing fibers is generally more suitable in the range of 5% - 15%, which can ensure that the fabric can recover well after stretching while providing sufficient freedom of movement. If there is large deformation at a fixed temperature, it cannot meet the wearing requirements of textiles and cannot be used. Description of the Drawings

[0022] Figure 1 is the preparation process of the coated yarn of the liquid crystal elastomer polymer in Example 1 of the present invention;

[0023] Figure 2 is the liquid crystal elastomer polymer in Example 1 of the present invention;

[0024] Figure 3 is the preparation equipment of the coated yarn of the liquid crystal elastomer polymer in Example 1 of the present invention;

[0025] Figure 4 is the coated yarn made of the liquid crystal elastomer polymer-coated polyester and spandex blended yarn in Example 1 of the present invention;

[0026] Figure 5 It is a covered yarn made of a liquid crystal elastomer polymer-coated cotton and spandex blended yarn in Embodiment 2 of the present invention;

[0027] Figure 6 It is a covered yarn made of a liquid crystal elastomer polymer-coated viscose and polyamide blended yarn in Embodiment 3 of the present invention;

[0028] Figure 7 It is a covered yarn made of a liquid crystal elastomer polymer-coated polyamide yarn in Embodiment 4 of the present invention;

[0029] Figure 8 It is a covered yarn made of a 5% concentration liquid crystal elastomer polymer solution-coated polyamide in Embodiment 5 of the present invention;

[0030] Figure 9 It is a covered yarn made of a 10% concentration liquid crystal elastomer polymer solution-coated polyamide in Embodiment 6 of the present invention;

[0031] Figure 10 It is a covered yarn made of a 20% concentration liquid crystal elastomer polymer solution-coated polyamide in Embodiment 7 of the present invention; Detailed implementation manners

[0032] The technical method of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The concentrations in the present invention are all mass concentrations unless otherwise specified.

[0033] As Figure 1 、 Figure 3 shown, it is a schematic diagram of the covering preparation process and principle adopted by the present invention. In some embodiments of the present invention, first, the LCE polymer shown in Figure 2 is added to an equal-volume mixed solvent of N, N-dimethylacetamide and dichloromethane to prepare an LCE solution, and then the yarn is passed through the LCE solution so that the LCE solution is coated on the yarn. After ultraviolet curing, it is wound, and it can also be dried after ultraviolet curing to obtain a liquid crystal elastomer covered yarn. As shown in the figure, the following specific method is adopted in the embodiments of the present invention: Take a 5 ml syringe to extract 3 ml of LCE solution, pass the yarn through the rubber stopper at the rear end of the syringe barrel, pass through the LCE solution in the syringe barrel, then select a needle that is thin enough but can pass the yarn, and then the yarn is pulled out from the needle. The needle is installed at the front end of the syringe. The pulled-out yarn is cured by an ultraviolet lamp, and finally wound into a cylinder by a collecting winding roller at a constant speed. Since the structure is not damaged, the original air pressure difference principle of the syringe is utilized. At the same time, due to the relatively high viscosity of the LCE solution, the LCE solution is not easily leaked from the syringe; with this simple device scheme, the present invention realizes the efficient and uniform coating of the yarn.

[0034] Embodiment 1

[0035] As Figure 1-3As shown in the figure, the preparation method of the LCE covered yarn includes the following steps: Dissolve the LCE polymer in an equal-volume mixed solvent of N,N-dimethylacetamide and dichloromethane, where the LCE concentration is 15%. Stir at 50 °C for 4-6 h, then put it into a self-made covering device. After the polyester and spandex blended yarn is covered by the covering device, it is cured by ultraviolet light irradiation, and finally through the winding device with a winding speed of 10 r / min.

[0036] After the temperature responsiveness test and mechanical property test, it is found that the breaking strength of the polyester and spandex blended yarn is about 5.82 N, and the elongation at break is about 18.16%. In terms of mechanical properties, it can basically meet the use requirements. However, its deformation rate at a fixed temperature (80 °C) can only be about 2%, with a very small change. At the same time, it can be seen from Figure 4 that the uniformity of the LCE covering layer is insufficient, probably because the surface of the yarn is too smooth, which is not conducive to the covering of LCE and does not meet the use requirements.

[0037] Example 2

[0038] As Figure 1-3 shown in the figure, the preparation method of the LCE covered yarn includes the following steps: Dissolve the LCE polymer in an equal-volume mixed solvent of N,N-dimethylacetamide and dichloromethane, so that the LCE concentration is 15%, that is, take 1 g of liquid crystal elastomer polymer particles, add 2.5 ml of N,N-dimethylacetamide and dichloromethane each, stir at 50 °C for 4-6 h, then put it into a self-made covering device. After the cotton and spandex blended yarn is covered by the covering device, it is cured by ultraviolet light irradiation, and finally through the winding device with a winding speed of 10 r / min. As shown in the figure, after testing, it is found that the breaking strength is only 2.67 N, and the elongation at break is only 3.48. Since the yarn is mainly cotton and has a core-spun yarn structure, the elasticity of the yarn itself is poor. Therefore, from the perspective of mechanical properties, it does not meet the performance requirements for use. Its deformation rate at a fixed temperature (80 °C) is only 1%, with a negligible change. The temperature-responsive characteristics of LCE are not brought into play.

[0039] Example 3

[0040] As Figure 1-3 shown in the figure, the preparation method of the LCE covered yarn includes the following steps: Dissolve the LCE polymer in an equal-volume mixed solvent of N,N-dimethylacetamide and dichloromethane, so that the LCE concentration is 15%, that is, take 1 g of liquid crystal elastomer polymer particles, add 2.5 ml of N,N-dimethylacetamide and dichloromethane each, stir at 50 °C for 4-6 h, then put it into a self-made covering device. After the viscose and polyamide blended yarn is covered by the covering device, it is cured by ultraviolet light irradiation, and finally through the winding device with a winding speed of 10 r / min. As Figure 6After testing, it was found that the breaking strength was only 4.09 N, the elongation at break was 12.43%, but its deformation rate at a fixed temperature (80 °C) was 2%, with a small change, and the temperature-responsive characteristics of the LCE were not exerted. It did not meet the application requirements.

[0041] Example 4

[0042] As Figure 1-3 shown, the preparation method of the LCE-covered yarn: includes the following steps: Dissolve the LCE polymer in an equal-volume mixed solvent of N,N-dimethylacetamide and dichloromethane to make the LCE concentration 15%, that is, take 1 g of liquid crystal elastomer polymer particles, add 2.5 ml each of N,N-dimethylacetamide and dichloromethane, stir at 50 °C for 4 - 6 h, then load it into a self-made covering device. After the pure polyamide yarn is covered by the covering device, it is cured by ultraviolet lamp irradiation, and finally through a winding device with a winding speed of 10 r / min. As Figure 7 shown, after testing, it was found that the breaking strength was 5.84 N, the elongation at break was 17.91%, and its deformation rate at a fixed temperature (80 °C) reached 5%. Compared with the first three samples, both the mechanical properties and the temperature-responsive properties were the best, and it basically met the usage requirements, so this sample met the requirements.

[0043] Example 5

[0044] After the tests and comparisons of the first four groups of samples, it was found that the pure polyamide yarn was the best choice in terms of mechanical properties, temperature-responsive properties, covering uniformity, etc. Therefore, next, try to change the concentration of the liquid crystal elastomer solution to explore the performance changes of the LCE-covered yarn. The preparation method of the LCE-covered yarn: includes the following steps: Dissolve the LCE polymer in an equal-volume mixed solvent of N,N-dimethylacetamide and dichloromethane to make the LCE concentration 5%, that is, take 0.3 g of LCE polymer particles, add 4.5 ml each of N,N-dimethylacetamide and dichloromethane, stir at 50 °C for 4 - 6 h, then load it into a self-made covering device. After the pure polyamide yarn is covered by the covering device, it is cured by ultraviolet lamp irradiation, and finally through a winding device with a winding speed of 10 r / min. As Figure 8 shown, after testing, it was found that the breaking strength was 5.2 N, the elongation at break was 22.73%, and its deformation rate at a fixed temperature (80 °C) was only about 1%. From Figure 8 the sample diagram, it can also be seen that the covering property of the 5% concentration LCE solution is poor, so this sample does not meet the requirements.

[0045] Example 6

[0046] As Figure 1-3As shown in the figure, the preparation method of the liquid crystal elastomer-coated yarn includes the following steps: Dissolve the LCE polymer in an equal-volume mixed solvent of N,N-dimethylacetamide and dichloromethane to make the LCE concentration 10%, that is, take 0.5 g of liquid crystal elastomer polymer particles, add 2 ml each of N,N-dimethylacetamide and dichloromethane, stir at 50 °C for 4 - 6 h, then put it into a self-made coating device. After the pure nylon yarn is coated by the coating device, it is cured by ultraviolet light irradiation, and finally through the winding device with a winding speed of 10 r / min. As Figure 9 shown, after testing, it is found that the breaking strength is 5.83 N, the breaking elongation rate is 22.36%, and its deformation rate at a fixed temperature (80 °C) is only about 2%. The temperature response characteristic is too small to meet the use requirements.

[0047] Example 7

[0048] As Figure 1-3 shown, the preparation method of the LCE-coated yarn includes the following steps: Dissolve the liquid crystal elastomer polymer in an equal-volume mixed solvent of N,N-dimethylacetamide and dichloromethane to make the LCE concentration 20%, that is, take 1 g of LCE polymer particles, add 1.8 ml each of N,N-dimethylacetamide and dichloromethane, stir at 50 °C for 4 - 6 h, then put it into a self-made coating device. After the pure nylon yarn is coated by the coating device, it is cured by ultraviolet light irradiation, and finally through the winding device with a winding speed of 10 r / min. As Figure 10 shown, after testing, it is found that the breaking strength is 6.3 N, the breaking elongation rate is 25.52%, and its deformation rate at a fixed temperature (80 °C) reaches about 8%, showing the characteristics of small deformation at a certain temperature. This small deformation meets the wearing requirements of environmentally responsive textiles. At the same time, the mechanical properties are also the best among all the tested samples. Compared with the original sample without coating the LCE solution, both the breaking strength and the breaking elongation rate have been improved.

Claims

1. A method for preparing a liquid crystal elastomer coated yarn, characterized in that: The following steps are involved: Dissolving liquid crystal elastomer (LCE) polymer particles in an organic solvent to prepare an LCE solution; Passing the yarn through the LCE solution so that the LCE solution is coated on the yarn; After curing with UV lamp, the coated yarn is collected by winding device; The collected coated yarn is placed in an oven for drying to obtain the liquid crystal elastomer coated yarn.

2. The method for preparing liquid crystal elastomer coated yarn according to claim 1, characterized in that: The organic solvent is a solution of N,N-dimethylacetamide and dichloromethane mixed in a volume ratio of 1:

1.

3. The method for preparing liquid crystal elastomer coated yarn according to claim 1, characterized in that: The mass concentration range of the liquid crystal elastomer in the LCE solution is 5%-20%.

4. The method for preparing liquid crystal elastomer coated yarn according to claim 1, characterized in that: The yarn is nylon yarn, polyester plus spandex blended yarn, cotton plus spandex blended yarn, viscose plus nylon blended yarn or silk.

5. The method for preparing liquid crystal elastomer coated yarn according to claim 1, characterized in that: The yarn is passed through the LCE solution so that the LCE solution is coated on the yarn. The specific method is as follows: a needle tube is used to extract the LCE solution, and the yarn is passed through the rubber plug at the rear end of the syringe, through the LCE solution in the syringe, and then a needle that is thin enough but can pass the yarn is selected, and then the yarn is pulled out from the needle, and the needle is installed at the front end of the needle tube. The pulled yarn is cured by an ultraviolet lamp and finally wound into a tube by a collecting winding roller.

6. The method for preparing liquid crystal elastomer coated yarn according to claim 1, characterized in that: The dissolution is carried out by stirring at 50° C. for 4-6 hours; after winding, the yarn is put into the UV light box again for 5 minutes of UV light curing treatment.

7. A liquid crystal elastomer coated yarn, characterized in that: The yarn is prepared by the method according to any one of claims 1 to 6, and has high elasticity, high recovery and temperature responsiveness.

8. The liquid crystal elastomer coated yarn according to claim 7, characterized in that: The deformation rate of the yarn at a fixed temperature of 80° C. is 8%-10%.

9. The liquid crystal elastomer coated yarn according to claim 7, characterized in that: The breaking strength of the yarn is greater than 5.8N, and the breaking elongation is greater than 17%.

10. An application of a liquid crystal elastomer coated yarn, characterized in that: The liquid crystal elastomer coated yarn is used in the fields of smart wearables, flexible electronics and environmentally responsive textiles.

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