Cholesteric liquid crystal microcapsule thermochromic composite alginate fiber and preparation method thereof

Abstract

The invention discloses a cholesteric liquid crystal microcapsule thermochromic composite alginate fiber and a preparation method thereof, and belongs to the technical field of thermochromic alginate fibers. According to the composite alginate fiber, alginate fiber serves as a base material, microencapsulated cholesteric liquid crystal serves as a temperature-sensitive color-changing substance, microencapsulation is carried out through an interfacial polymerization method, the microencapsulated cholesteric liquid crystal is mixed with a dark-color substance, and the mixture is evenly dispersed in the fiber and on the surface of the fiber. The preparation method comprises the following steps: uniformly mixing alginate and an additive, then carrying out secondary mixing on the mixture, cholesteric liquid crystal microcapsules and part of dark-color substances, standing and defoaming to obtain a primary spinning solution, and pressing the primary spinning solution into a coagulating bath tank through a spinning nozzle based on a wet spinning technology to be coagulated and formed. And finally, filling gaps on the surface of the fiber by using a transparent polymer, and carrying out ultraviolet irradiation polymerization to obtain the colored fiber bundle capable of realizing full-spectrum color change along with temperature change. The composite alginate fiber has good heat resistance, washing resistance, friction resistance, mechanical stretchability and quick response thermosensitive discoloration.

Description

Technical Field

[0001] The invention relates to a fiber and a preparation method thereof, in particular to a full-spectrum thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber with a transparent polymer filled on the surface, belonging to the technical field of thermochromic seaweed fibers. Background Art

[0002] In recent years, with people's continuous pursuit of personalized clothing, traditional colored clothing has gradually failed to meet people's needs. The textile field has witnessed the continuous emergence of intelligent color-changing fibers. Among them, the continuous innovation of fiber technology is particularly eye-catching, paving a broad development path for the global textile and clothing industries. In 2018, Professor Zhu Ping's research group at Qingdao University combined thermochromic materials with seaweed fibers to prepare thermochromic seaweed fibers that can achieve blue and white interchanging between 37°C and 38°C. However, the temperature-sensitive color change range of the fiber is narrow, the color change is relatively single, and only blue and white changes can be achieved. In addition, in 2024, Professor Xia Yanzheng's research group at Qingdao University filled microcapsules coated with traditional thermochromic materials into seaweed fibers, which can achieve black and white color changes at 10°C-30°C, and the color change is relatively single; in addition, thermochromic microcapsule composite fibers of other colors, due to the uneven fiber surface after coating the microcapsules, lead to a large scattering effect, and the fiber color often appears whitish and uneven, which greatly limits its application effect. Summary of the invention

[0003] In order to solve the existing technical problems, the present invention provides a full-spectrum thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber with a transparent polymer filling the surface. The material is based on seaweed fiber, and cholesteric liquid crystal microcapsules or a mixture thereof with a dark substance are embedded in the interior and surface of the seaweed fiber, and transparent polymers are used to fill the gaps on the fiber surface and then polymerize. This method of uniformly dispersing cholesteric liquid crystal microcapsules or a mixture thereof with a dark substance inside the seaweed fiber, the prepared fiber color has full-spectrum continuous reversible color change and stability; because the external transparent polymer is polymerized after filling the fiber gaps to form an external polymer network, while reducing the effect of fiber surface scattering on color development, the fiber has good mechanical tensile properties and higher color saturation and is brighter.

[0004] The present invention provides a unique fiber external polymerization method, wherein cholesteric liquid crystal microcapsules or a mixture thereof with dark substances and polymers are prepared into a spinning solution, and then a thermochromic fiber is prepared using a wet spinning device. After that, the fiber surface voids are filled with a transparent liquid polymer, and then ultraviolet light is polymerized to form an external polymer network. This method of externally polymerizing the fiber surface reduces the effect of surface scattering on the color development of the fiber, making the fiber color development saturation and brightness higher, and the mechanical tensile properties of the fiber stronger.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing composite seaweed fiber comprises the following steps: S1. Preparation of cholesteric liquid crystal thermochromic microcapsules: cholesteric mixed liquid crystal as capsule core and external polymer shell as capsule wall; The capsule core comprises one or more of cholesterol oleyl carbonate, cholesterol nonanoate, cholesterol chloride, cholesterol benzoate, cholesterol acetate, cholesterol stearate, and cholesterol valerate; The capsule wall comprises one of polyurea, polymethyl methacrylate, melamine formaldehyde resin, polyurethane, gelatin, complex coagulation material and epoxy resin; S2, preparing cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber: spinning, curing, stretching and drying the spinning stock solution containing cholesteric liquid crystal thermochromic microcapsule to obtain cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber; S3. Preparation of cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber after transparent polymer surface polymerization: immersing the cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber in a transparent liquid polymer monomer containing a photoinitiator, polymerizing under ultraviolet light, to obtain the cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber after transparent polymer surface polymerization.

[0006] Furthermore, in step S1, the preparation process of the cholesteric liquid crystal thermochromic microcapsules is: adding the capsule core to the monomer solution of the capsule wall as an oil tank; then adding the aqueous solution, stirring and emulsifying, catalyzing the reaction, and washing and drying after the reaction to obtain the cholesteric liquid crystal thermochromic microcapsules.

[0007] Furthermore, the aqueous phase solution is a polyvinyl alcohol solution, and the catalyst used in the catalytic reaction is dibutyltin dilaurate.

[0008] Furthermore, in the step (2), the spinning solution includes alginate, additives and cholesteric liquid crystal thermochromic microcapsules; Firstly, alginate is dissolved in water, then additives are added, and then the alginate is mixed with cholesteric liquid crystal microcapsules or a mixture of the alginate and dark-colored substances for a second time.

[0009] Furthermore, the alginate is one or more of sodium alginate, potassium alginate, lithium alginate, ammonium alginate, zinc alginate, iron alginate, copper alginate, silver alginate, nickel alginate, and barium alginate; The additive is one or more of polyvinyl alcohol, polyethylene glycol, chitosan, gelatin, polyacrylamide and polyvinyl pyrrolidone.

[0010] Furthermore, the mass ratio of alginate, additive and cholesteric liquid crystal thermochromic microcapsule in the spinning solution is 1:(0.3-0.5):1.

[0011] Furthermore, the mass percentage concentration of alginate is 1%-6%; and the amount of the additive added is 1%-60% of the mass of alginate.

[0012] Furthermore, in step (3), the transparent liquid polymer monomer includes one or more of hydroxyethyl acrylate, acrylic acid, methyl methacrylate, lauryl acrylate, isooctyl acrylate, N,N-dimethylacrylamide, 4-hydroxybutyl acrylate, epoxy acrylate, glycidyl methacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, and isobornyl acrylate.

[0013] Specifically: a full-spectrum thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber with transparent polymer filling on the surface, comprising the following steps: a. Dissolve alginate in water and add additives to form hydrogen bond structures between the molecular chains, mix with cholesteric liquid crystal microcapsules or a mixture of the alginate and dark-colored substances at a specified temperature, and let stand to degas; b. Take out the mixed solution and supply it to the filter in a quantitative manner using a metering pump.

[0014] c. The filtered spinning solution is spun by wet spinning, and then the gaps on the fiber surface are filled with transparent liquid polymer monomers, and ultraviolet light is used for polymerization to prepare thermal-sensitive full-spectrum color-changing fibers.

[0015] Furthermore, in step a, the temperature is 20-60°C.

[0016] Further, in step c, the transparent liquid polymer monomer includes one or more or a complex of hydroxyethyl acrylate, acrylic acid, methyl methacrylate, lauryl acrylate, isooctyl acrylate, N,N-dimethylacrylamide, 4-hydroxybutyl acrylate, epoxy acrylate, glycidyl methacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, and isobornyl acrylate.

[0017] Furthermore, in step a, the standing degassing time is 12h-24h.

[0018] Furthermore, the coagulation bath includes 1%-6% CaCl 2 Aqueous solution, temperature between 20-80℃.

[0019] Furthermore, alginate is dissolved in the additive, stirred evenly, and then stirred twice with the cholesteric liquid crystal microcapsules. After the solution is mixed evenly, a spinning solution is obtained, which is quantitatively supplied to the filter by a metering pump for filtration, and is pressed into a coagulation bath through a nozzle for coagulation and forming. It is introduced into a preheating bath through a winding roller, and the preheating bath temperature is 20-80°C for preheating and stretching. The fiber bundle treated in the preheating bath is introduced into a washing tank for washing to wash away impurities on the fiber. After washing, the tow is dried and other processes to obtain fiber filaments. Afterwards, the voids on the fiber surface are filled with a transparent liquid polymer, and ultraviolet light is used for polymerization to obtain a thermosensitive full-spectrum color-changing fiber.

[0020] A composite seaweed fiber is prepared by adopting the above preparation method.

[0021] A full-spectrum thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber with transparent polymer polymerized on the surface, which is based on seaweed fiber, and cholesteric liquid crystal microcapsules or a mixture thereof with 1%-2% dark matter are uniformly mixed and embedded on the surface and inside of the polymer fiber. Then, the transparent polymer is filled into the gaps on the fiber surface and polymerized by ultraviolet light.

[0022] Furthermore, the alginate includes one or more of sodium alginate, potassium alginate, lithium alginate, ammonium alginate, zinc alginate, iron alginate, copper alginate, silver alginate, nickel alginate, and barium alginate.

[0023] Furthermore, the cholesteric liquid crystal microcapsule is a capsule core of a cholesteric mixed liquid crystal, and the outside is encapsulated by a polymer microcapsule wall to form a core-shell structure. The preparation of the cholesteric liquid crystal microcapsule is generally prepared by an interfacial polymerization method and a solvent volatilization method. The mixed cholesteric mixed liquid crystal and the wall material monomer are dissolved in an organic phase solvent such as dichloromethane, and then mixed with an aqueous phase with an emulsifier, emulsified at high speed, and then reacted at a certain temperature and speed for a period of time. After the reaction is completed, centrifugal washing is performed to obtain a cholesteric liquid crystal microcapsule that can achieve thermal full-spectrum color change.

[0024] Furthermore, the dark-colored substance includes one or more mixtures or composites of carbon black, carbon nanotubes, organic black dyes, and graphene.

[0025] Furthermore, the cholesteric phase microcapsule core mixed liquid crystal includes one or more of cholesterol oleyl carbonate, cholesterol nonanoate, cholesterol chloride, cholesterol benzoate, cholesterol acetate, cholesterol stearate, and cholesterol valerate.

[0026] Furthermore, the capsule wall of the cholesteric liquid crystal microcapsule includes one or more of polyurea, polymethyl methacrylate, melamine formaldehyde resin, polyurethane, gelatin, complex condensation material, and epoxy resin.

[0027] Furthermore, the transparent liquid polymer monomer includes one or more or a complex of hydroxyethyl acrylate, acrylic acid, methyl methacrylate, lauryl acrylate, isooctyl acrylate, N,N-dimethylacrylamide, 4-hydroxybutyl acrylate, epoxy acrylate, glycidyl methacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, and isobornyl acrylate.

[0028] Furthermore, the particle size of the cholesteric liquid crystal microcapsule is 10-30 μm, wherein the capsule wall thickness of the cholesteric liquid crystal microcapsule is 300-500 nm, wherein the particle size of the cholesteric liquid crystal microcapsule is preferably 10-15 μm, and the capsule wall thickness of the cholesteric liquid crystal microcapsule is preferably 300-350 nm. The color saturation of the microcapsule changes with the capsule wall thickness.

[0029] Furthermore, the fiber diameter is 5-500 μm, wherein the fiber diameter is preferably 100-150 μm.

[0030] Furthermore, the cholesteric liquid crystal microcapsules or a mixture thereof with a dark substance are uniformly dispersed and embedded in the interior and surface of the fiber, wherein the content of the cholesteric liquid crystal microcapsules is 1-30% of the content of the alginate, and preferably the content of the cholesteric liquid crystal microcapsules is 10%-20%.

[0031] Beneficial effects of the present invention: The present invention selects cholesteric liquid crystal as a thermochromic substance, and adjusts the color change temperature range and color change types through liquid crystal mixing, so as to achieve reversible color change in the full spectrum of visible light. It is individually encapsulated by microcapsule technology, and the thermochromic cholesteric liquid crystal microcapsules are embedded in the interior and surface of the fiber by wet spinning technology. Then, transparent polymers are used to fill and polymerize the surface gaps to eliminate the scattering effect as much as possible and improve the color saturation. This transformation not only enables the fiber to achieve a continuous reversible change from red to purple under temperature changes, but also solves the problem that liquid crystal is not easy to be directly fixed on the surface of the substrate due to fluidity during use and the color development has angle dependence. At the same time, the external polymer network significantly improves its mechanical properties. Specifically, the friction resistance of this new type of thermochromic fiber reaches the fifth level standard, and it also performs well in water washability, mechanical stretching, heat resistance and light stability.

[0032] The present invention innovatively introduces thermosensitive full-spectrum color-changing cholesteric liquid crystal microcapsule composite seaweed fiber with a transparent polymer network filling on the outside, which has good friction resistance, water washing resistance, heat resistance, mechanical stretchability and fast-response thermosensitive color changing properties, and the color saturation is higher and brighter. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1This is a scanning electron microscope photograph of the thermochromic cholesteric liquid crystal microcapsule prepared in Example 1 of the present invention.

[0034] Figure 2 This is a scanning electron microscope photograph of the surface and cross-section of the thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber prepared in Example 1 of the present invention before polymerization.

[0035] Figure 3 This is a scanning electron microscope photograph of the surface of the thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber after polymerization prepared in Example 1 of the present invention.

[0036] Figure 4 This is a microscope photo of the surface of the thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber before polymerization prepared in Example 1 of the present invention. Figure 5 This is a microscope photograph of the surface of the thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber after polymerization prepared in Example 1 of the present invention.

[0037] Figure 6 This is a photograph of the test results of the single fiber strength of the thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber before and after polymerization prepared in Example 1 of the present invention.

[0038] Figure 7 This is a microscope photograph of the full-spectrum color change experimental results of a single thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be described below in conjunction with embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0040] The present invention relates to a method for preparing a full-spectrum thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber with a transparent polymer polymerized on the surface, and the specific steps are as follows: (1) Preparation of cholesteric mixed liquid crystal: cholesterol oleyl carbonate, cholesterol nonanoate, cholesterol acetate, cholesterol chloride and cholesterol benzoate were mixed in a 20 ml sample bottle at a mass ratio of 1:2:2:3:2 with a total mass of 1 g, heated to 70° C., and stirred at 400 rpm for 30 min to obtain a cholesteric mixed liquid crystal that can achieve spectral color change from red to purple at 25° C. to 75° C.; (2) Preparation of cholesteric liquid crystal thermochromic microcapsules: The cholesteric mixed liquid crystal was microencapsulated by interfacial polymerization. 1g of cholesteric mixed liquid crystal was dissolved in 10ml of dichloromethane, and then 0.25g of isophorone diisocyanate was added and stirred for 30min as the oil phase; 2g of polyvinyl alcohol was dissolved in 98g of water to prepare a 2%wt polyvinyl alcohol (PVA) solution as the aqueous phase and surfactant. 40g of 2% PVA solution was transferred to a 500ml three-necked flask, mechanically stirred at 150rpm, and the oil phase was added to the three-necked flask in a dropwise manner. After the dropwise addition was completed, the mechanical stirring was changed to 1000rpm, and emulsified for 30min, and then the speed was adjusted to 300rpm. 1% of the total system mass of dibutyltin dilaurate was added as a system catalyst, and the reaction temperature was adjusted to 40℃. The reaction was carried out for 6h. After the reaction was completed, the mixture was centrifuged, washed with water, and dried to obtain cholesteric liquid crystal thermochromic microcapsules; (3) Preparing a cholesteric liquid crystal thermochromic microcapsule aqueous solution: 2 g of cholesteric liquid crystal thermochromic microcapsules were mixed with 8 g of water to prepare a cholesteric liquid crystal thermochromic microcapsule aqueous solution; (4) preparing spinning solution: preparing 100 g of a sodium alginate aqueous solution with a mass percentage concentration of 2%, adding 0.8 g of polyvinyl alcohol as an additive to form hydrogen bonds between molecular chains, and mixing with the cholesteric liquid crystal thermochromic microcapsule aqueous solution obtained in step (3), and then adding carbon black with a mass percentage concentration of 1% of the spinning solution as a dark substance, stirring at room temperature and 300 r / min for 12 h, and then standing for degassing for 12 h to obtain a spinning solution; (5) Preparation of cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber: the spinning solution is extruded through a spinneret, solidified into filaments in a calcium chloride coagulation bath with a mass percentage concentration of 4%, and the temperature of the coagulation bath water tank is maintained at 30°C, and then fixed in a calcium chloride stretching bath with a mass percentage concentration of 4%, washed and dried to obtain cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber; (6) Preparing transparent polymer surface-polymerized cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber: immersing the cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber obtained in step (5) in a hydroxyethyl acrylate solution to which 1173 photoinitiator is added at a mass fraction of 1%, and polymerizing under ultraviolet light for 5 minutes to obtain transparent polymer surface-polymerized cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber; Example 2

[0041] The present invention relates to a method for preparing a full-spectrum thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber with transparent polymer polymer filling on the surface, and the specific steps are as follows: (1) Preparation of cholesteric mixed liquid crystal: the specific steps are the same as those in Example 1; (2) Preparation of cholesteric liquid crystal thermochromic microcapsules: The specific steps are the same as those in Example 1; (3) Preparation of cholesteric liquid crystal thermochromic microcapsule aqueous solution: 2 g of thermochromic microcapsules were mixed with 8 g of water to prepare a thermochromic microcapsule aqueous solution; (4) preparing a spinning solution: preparing 100 g of a sodium alginate aqueous solution with a mass percentage concentration of 3%, adding 1.2 g of polyvinyl alcohol as an additive, and mixing with the cholesteric liquid crystal thermochromic microcapsule aqueous solution obtained in step (3), and then adding carbon black with a mass percentage concentration of 1% of the spinning solution as a dark substance, stirring at room temperature and 300 r / min for 12 h, and then standing for degassing for 12 h to obtain a spinning solution; (5) Preparation of cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber: extruding the spinning solution through a spinneret, solidifying it into filaments in a calcium chloride coagulation bath with a mass percentage concentration of 5%, and maintaining the coagulation bath water tank temperature at 30°C, and then shaping it in a calcium chloride stretching bath with a mass percentage concentration of 5%, washing and drying, to obtain cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber; (6) Preparing a transparent polymer surface-polymerized cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber: immersing the cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber obtained in step (5) in an acrylic acid solution to which a 1173 photoinitiator with a mass fraction of 1% is added, polymerizing under ultraviolet light for 5 minutes to obtain a transparent polymer surface-polymerized cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber; Example 3

[0042] The present invention relates to a method for preparing a full-spectrum thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber with transparent polymer polymer filling on the surface, and the specific steps are as follows: (1) Preparation of cholesteric mixed liquid crystal: the specific steps are the same as those in Example 1; (2) Preparation of cholesteric liquid crystal thermochromic microcapsules: The specific steps are the same as those in Example 1; (3) Preparation of cholesteric liquid crystal thermochromic microcapsule aqueous solution: 2 g of thermochromic microcapsules were mixed with 8 g of water to prepare a thermochromic microcapsule aqueous solution; (4) preparing a spinning solution: preparing 100 g of a sodium alginate aqueous solution with a mass percentage concentration of 4%, adding 2.4 g of polyvinyl alcohol as an additive, and mixing with the cholesteric liquid crystal thermochromic microcapsule aqueous solution obtained in step (3), and then adding carbon black with a mass percentage concentration of 1% of the spinning solution as a dark substance, stirring at room temperature and 300 r / min for 12 h, and then standing for degassing for 12 h to obtain a spinning solution; (5) Preparation of cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber: the spinning solution is extruded through a spinneret, solidified into filaments in a calcium chloride coagulation bath with a mass percentage concentration of 6%, and the temperature of the coagulation bath water tank is maintained at 30°C, and then fixed in a calcium chloride stretching bath with a mass percentage concentration of 6%, washed and dried to obtain cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber; (6) Preparing transparent polymer surface-polymerized cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber: soaking the cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber obtained in step (5) in methyl methacrylate to which 1 mass% 1173 photoinitiator is added, polymerizing under ultraviolet light for 5 min, and obtaining transparent polymer surface-polymerized cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber; Example 4

[0043] The present invention relates to a method for preparing a full-spectrum thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber with transparent polymer polymer filling on the surface, and the specific steps are as follows: (1) Preparation of cholesteric mixed liquid crystal: the specific steps are the same as those in Example 1; (2) Preparation of cholesteric liquid crystal thermochromic microcapsules: The specific steps are the same as those in Example 1; (3) Preparation of cholesteric liquid crystal thermochromic microcapsule aqueous solution: 2 g of thermochromic microcapsules were mixed with 8 g of water to prepare a thermochromic microcapsule aqueous solution; (4) preparing a spinning solution: preparing 100 g of a sodium alginate aqueous solution with a mass percentage concentration of 4%, adding 3 g of polyvinyl alcohol as an additive, and mixing with the cholesteric liquid crystal thermochromic microcapsule aqueous solution obtained in step (3), and then adding carbon black with a mass percentage concentration of 2% of the spinning solution as a dark substance, stirring at room temperature and 300 r / min for 12 h, and then standing for degassing for 12 h to obtain a spinning solution; (5) Preparation of cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber: the spinning solution is extruded through a spinneret, solidified into filaments in a calcium chloride coagulation bath with a mass percentage concentration of 6%, and the temperature of the coagulation bath water tank is maintained at 30°C, and then fixed in a calcium chloride stretching bath with a mass percentage concentration of 6%, washed and dried to obtain cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber; (6) Preparing transparent polymer surface-polymerized cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber: soaking the cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber obtained in step (5) in 1% by mass of 1173 photoinitiator isooctyl acrylate monomer, polymerizing under ultraviolet light for 5 min to obtain transparent polymer surface-polymerized cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber; Example 5

[0044] The present invention relates to a method for preparing a full-spectrum thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber with transparent polymer polymer filling on the surface, and the specific steps are as follows: (1) Preparation of cholesteric mixed liquid crystal: the specific steps are the same as those in Example 1; (2) Preparation of cholesteric liquid crystal thermochromic microcapsules: The specific steps are the same as those in Example 1; (3) Preparation of cholesteric liquid crystal thermochromic microcapsule aqueous solution: 2 g of thermochromic microcapsules were mixed with 8 g of water to prepare a thermochromic microcapsule aqueous solution; (4) preparing a spinning solution: preparing 100 g of a sodium alginate aqueous solution with a mass percentage concentration of 1%, adding 0.6 g of polyvinyl alcohol as an additive, and mixing with the cholesteric liquid crystal thermochromic microcapsule aqueous solution obtained in step (3), and then adding carbon black with a mass percentage concentration of 2% of the spinning solution as a dark substance, stirring at room temperature and 300 r / min for 12 h, and then standing for degassing for 12 h to obtain a spinning solution; (5) Preparation of cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber: the spinning solution is extruded through a spinneret, solidified into filaments in a calcium chloride coagulation bath with a mass percentage concentration of 6%, and the temperature of the coagulation bath water tank is maintained at 30°C, and then fixed in a calcium chloride stretching bath with a mass percentage concentration of 6%, washed and dried to obtain cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber; (6) Preparing transparent polymer surface-polymerized cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber: immersing the cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber obtained in step (5) in lauryl acrylate to which 1173 photoinitiator is added at a mass fraction of 1%, and polymerizing under ultraviolet light for 5 minutes to obtain transparent polymer surface-polymerized cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber; Example 6

[0045] The present invention relates to a method for preparing a full-spectrum thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber with transparent polymer polymer filling on the surface, and the specific steps are as follows: (1) Preparation of cholesteric mixed liquid crystal: the specific steps are the same as those in Example 1; (2) Preparation of cholesteric liquid crystal thermochromic microcapsules: The specific steps are the same as those in Example 1; (3) Preparation of cholesteric liquid crystal thermochromic microcapsule aqueous solution: 2 g of thermochromic microcapsules were mixed with 8 g of water to prepare a thermochromic microcapsule aqueous solution; (4) preparing a spinning solution: preparing 100 g of a sodium alginate aqueous solution with a mass percentage concentration of 4%, adding 1.6 g of polyvinyl alcohol as an additive and mixing it with the cholesteric liquid crystal thermochromic microcapsule aqueous solution obtained in step (3), then adding carbon black with a mass percentage concentration of 2% of the spinning solution as a dark substance, stirring at room temperature and 300 r / min for 12 h, and then standing and degassing for 24 h to obtain a spinning solution; (5) Preparation of cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber: the spinning solution is extruded through a spinneret, solidified into filaments in a calcium chloride coagulation bath with a mass percentage concentration of 4%, and the temperature of the coagulation bath water tank is maintained at 25°C, and then fixed in a calcium chloride stretching bath with a mass percentage concentration of 4%, washed and dried to obtain cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber; (6) Preparing a transparent polymer surface-polymerized cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber: immersing the cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber obtained in step (5) in pentaerythritol triacrylate to which 1 mass% of 1173 photoinitiator is added, polymerizing under ultraviolet light for 5 min to obtain a transparent polymer surface-polymerized cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber; Compared with other examples, Example 5 and Example 1 have lower elongation at break and maximum stress. The concentration of sodium alginate determines the mechanical properties of seaweed fiber. As the concentration of sodium alginate increases, the maximum stress and elongation at break gradually increase. Compared with Example 4 and Example 5, as the amount of polyvinyl alcohol added increases, the number of hydrogen bonds between polyvinyl alcohol and seaweed molecules increases, and the maximum stress that the fiber can withstand increases, but the plasticity of the composite seaweed fiber decreases, and the elongation at break decreases. The coagulation bath concentration will affect the Ca 2+ and Na + The exchange rate of ions is generally higher when the concentration of the coagulation bath is higher, the faster the ion exchange rate is, the greater the maximum stress that the fiber can withstand, the tight crosslinking between molecules, the limited molecular activity, and the reduced elongation at break. At the same time, compared with Examples 1, 2, and 3 and Examples 4, 5, and 6, the increase in the amount of carbon black added will increase the overall color brightness and reflectivity of the fiber. Example 7

[0046] This example relates to the characterization and performance testing of the full-spectrum thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber filled with a transparent polymer on the surface prepared in Example 1.

[0047] The cholesteric liquid crystal microcapsules prepared in Example 1 were characterized by scanning electron microscopy. Figure 1 shown.

[0048] from Figure 1It can be seen that the cholesteric liquid crystal microcapsules are spherical and have a particle size distribution between 1-20 μm.

[0049] The surface and cross section of the thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber prepared in Example 1 before polymerization were characterized by scanning electron microscopy. The results are as follows: Figure 2 shown.

[0050] from Figure 2 It can be seen that the surface of the thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber presents spherical protrusions, and the internal cross-section also presents spherical holes, indicating that the cholesteric liquid crystal microcapsules are successfully loaded inside and on the surface of the composite seaweed fiber.

[0051] The surface of the thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber prepared in Example 1 was characterized by scanning electron microscopy after polymerization. The results are as follows: Figure 3 shown.

[0052] from Figure 3 It can be seen that compared with the surface without transparent polymer filling, the surface flatness of the seaweed fiber is improved, and exposed spherical microcapsules and surface spherical protrusions are rarely seen on the surface.

[0053] The surface of the thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber prepared in Example 1 before and after polymerization was characterized by optical microscopy. The results are as follows: Figure 4 and Figure 5 shown.

[0054] from Figure 4 and Figure 5 It can be seen from the comparison that before the transparent polymer is filled into the fiber surface, the color of the seaweed fiber is seriously affected by the scattering of the uneven surface, the color saturation is low, and the color is whitish. After the transparent polymer monomer is filled into the surface gap and polymerized by ultraviolet light, the scattering effect is significantly improved, and the color saturation and brightness of the seaweed fiber are greatly improved.

[0055] The single fiber strength test and comparison of the thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber prepared in Example 1 before and after polymerization are as follows: Figure 6 As shown. Figure 6 It can be seen that the stress and strain of the fiber are greatly improved after surface polymer filling, with higher strength and greater strain.

[0056] The thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber filled with transparent polymer on the surface prepared in Example 1 was subjected to a thermochromic color change test. The fiber filled with transparent polymer on the surface was placed on a heating table and heated from 25°C to 75°C, then placed under an optical microscope and photographed to record the color change. The results are shown in the figure. Figure 7 As shown. Figure 7It can be seen that at 25°C, the fiber is red, and as the temperature rises, it gradually changes from red to orange, yellow, green, cyan, and blue. When the temperature rises to 75°C, the fiber color turns purple. Repeated cooling and heating can cause continuous reversible changes.

[0057] As described above, the full-spectrum thermochromic cholesteric liquid crystal microcapsule composite seaweed fiber with transparent polymer filling on the surface prepared by the present invention has high sensitivity to the increase of ambient temperature, and can undergo a full-spectrum color change reaction from red to purple during the temperature rise and fall process from 25°C to 75°C.

[0058] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing composite seaweed fiber, characterized in that: The following steps are involved: S1. Preparation of cholesteric liquid crystal thermochromic microcapsules: cholesteric mixed liquid crystal as capsule core and external polymer shell as capsule wall; The capsule core comprises one or more of cholesterol oleyl carbonate, cholesterol nonanoate, cholesterol chloride, cholesterol benzoate, cholesterol acetate, cholesterol stearate, and cholesterol valerate; The capsule wall comprises one of polyurea, polymethyl methacrylate, melamine formaldehyde resin, polyurethane, gelatin, complex coagulation material and epoxy resin; S2, preparing cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber: spinning, curing, stretching and drying the spinning stock solution containing cholesteric liquid crystal thermochromic microcapsule to obtain cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber; S3. Preparation of cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber after transparent polymer surface polymerization: immersing the cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber in a transparent liquid polymer monomer containing a photoinitiator, polymerizing under ultraviolet light, to obtain the cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber after transparent polymer surface polymerization.

2. The method for preparing a composite seaweed fiber according to claim 1, characterized in that: In the step S1, the preparation process of the cholesteric liquid crystal thermochromic microcapsules is as follows: adding the capsule core to the monomer solution of the capsule wall as an oil tank; then adding the aqueous solution, stirring and emulsifying, catalyzing the reaction, and washing and drying after the reaction to obtain the cholesteric liquid crystal thermochromic microcapsules.

3. The method for preparing a composite seaweed fiber according to claim 2, characterized in that: The aqueous phase solution is a polyvinyl alcohol solution, and the catalyst used in the catalytic reaction is dibutyltin dilaurate.

4. The method for preparing a composite seaweed fiber according to claim 1, characterized in that: In the step (2), the spinning solution includes alginate, additives, cholesteric liquid crystal thermochromic microcapsules and dark-colored substances; the alginate is first dissolved in water, the additives are added, and then the alginate is mixed with the cholesteric liquid crystal microcapsules and the dark-colored substances for a second time.

5. The method for preparing a composite seaweed fiber according to claim 4, characterized in that: The alginate is one or more of sodium alginate, potassium alginate, lithium alginate, ammonium alginate, zinc alginate, iron alginate, copper alginate, silver alginate, nickel alginate, and barium alginate; The additive is one or more of polyvinyl alcohol, polyethylene glycol, chitosan, gelatin, polyacrylamide, and polyvinyl pyrrolidone; The dark substance is one or more of carbon black, carbon nanotubes, organic black dye, and graphene.

6. The method for preparing a composite seaweed fiber according to claim 4, characterized in that: The spinning solution includes alginate, additives and cholesteric liquid crystal thermochromic microcapsules in a mass ratio of 1: (0.3-0.5): 1, and the dark substance accounts for 1%-2% of the mass percentage concentration of the spinning solution.

7. The method for preparing a composite seaweed fiber according to claim 1, characterized in that: The mass percentage concentration of alginate is 1%-6%; The additive is added in an amount of 1%-60% of the mass of the alginate.

8. The method for preparing a composite seaweed fiber according to claim 1, characterized in that: In the step (3), the transparent liquid polymer monomer includes one or more of hydroxyethyl acrylate, acrylic acid, methyl methacrylate, lauryl acrylate, isooctyl acrylate, N,N-dimethylacrylamide, 4-hydroxybutyl acrylate, epoxy acrylate, glycidyl methacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, and isobornyl acrylate.

9. A composite seaweed fiber, characterized in that: The method is prepared by any one of claims 1 to 8.

10. The composite seaweed fiber according to claim 9, characterized in that: The diameter of the composite seaweed fiber is 5-500 μm; in the composite seaweed fiber, the particle size of the cholesteric liquid crystal microcapsule is 10-30 μm, wherein the thickness of the polymer capsule wall is 300-500 nm; The cholesteric liquid crystal microcapsules are mixed with dark substances and embedded in the interior and surface of the cholesteric liquid crystal thermochromic microcapsule composite seaweed fiber.

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