CN112267174A - Method for preparing electrochromic fiber without external electrode by coaxial microfluid spinning method - Google Patents
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Abstract
The invention discloses a method for preparing electrochromic fibers without an external electrode by a coaxial microfluid spinning method, belonging to the technical field of fine chemical engineering and material science. The invention adopts a coaxial micro-flow spinning method to prepare the electrochromic liquid crystal fiber which takes black conductive polymer as an inner conductive layer, a transparent metal nanowire layer as an outer conductive layer and polymer dispersed cholesteric liquid crystal as an electrochromic layer, wherein the mass ratio of the metal nanowire layer, the black conductive layer and the cholesteric liquid crystal layer is 5-30: 100: 5 to 30. The electrochromic liquid crystal fiber prepared by the method can reversibly change color under the stimulation of an electric field, can realize a continuous stable state of a certain color change state under the condition of power failure, is bright and changeable in color, has low driving voltage lower than 23.9V (lower than the human body safety voltage of 36V), and has good solvent resistance and water resistance.
Description
Technical Field
The invention relates to a method for preparing electrochromic fibers without an external electrode by a coaxial microfluid spinning method, belonging to the technical field of fine chemical engineering and material science.
Background
The increasingly strong technological and personalized requirements have become new challenges and trends in the development of the textile and clothing industry. The intelligent textile is a novel textile which is built on textile base materials and technical characteristics, simulates a life system and has double functions of perception and reflection. The fabric has the performance of common fabric, can intelligently sense the change of external conditions, processes information through self-sensing, sends out instructions and executes actions. The electrochromic material can change the optical properties (reflectivity, transmittance, absorptivity and the like) of the textile under the stimulation of an electric field, so that the electrochromic material can show reversible change of color or light transmittance macroscopically, has wide application in the aspects of military protection hidden materials, flexible display, anti-counterfeiting marks, safety warnings, artistic ornaments and the like, and is a key component for sensing and visually feeding back the change of the external environment of the intelligent textile.
Different from the traditional electrochemical working mechanism of electrochromic materials, the electric stimulation response color change of the cholesteric liquid crystal is a physical change process, and has the advantages of long service life, quick response time, full spectrum display from a transparent state to a colored state and the like. However, cholesteric liquid crystals flow easily during device flexing and are difficult to shape; meanwhile, the spiral structure of the cholesteric liquid crystal exists in the form of intermolecular force, so that the cholesteric liquid crystal is very easily influenced by the external environment and loses electrochromic performance; in addition, most of the conventional electrochromic liquid crystal devices are rigid devices using glass as a substrate, but with the intelligentization of textile products such as clothes, development of flexible electrochromic devices is urgently needed. These have all greatly limited their further use in textiles. Compared with the traditional two-dimensional or three-dimensional device, the diameter of the fibrous electronic device is between tens of microns and hundreds of microns, the fibrous electronic device belongs to a one-dimensional structure, and the fibrous electronic device has the characteristics of light weight, good flexibility, strong knittability and the like. The advantages of the fiber device such as scalability, self-healing and shape memory are fully utilized, and the fiber device is woven into a flexible, deformable, breathable and waterproof intelligent textile, which is an important development direction of electrochromic liquid crystal devices.
At present, few researches are carried out on the application of electrochromic liquid crystal on textiles at home and abroad, and methods such as microcapsule coating and the like are mainly adopted. For example, chinese patents zl201711404913.x and zl201811152977.x prepare liquid crystal microcapsules with smooth surface and uniform particle size distribution by emulsion polymerization, and further prepare color-changing textiles by using the liquid crystal microcapsules to prepare electrochromic coatings. However, the above method is not suitable for the preparation of electrochromic liquid crystal fibers because the liquid crystal is easily doped in the polymer matrix during the preparation of microcapsules to cause staining phenomenon, and meanwhile, the microcapsule coating method still cannot get rid of the application limitation of the additional electrode and cannot meet the requirement of air permeability and flexibility of textiles.
Therefore, based on a large-area electrochromic mechanism, the traditional additional rigid electrode is flexible and integrated, so that the technical bottleneck of the fibrosis of the flexible liquid crystal electrochromic material is overcome, the continuous preparation and application of the intelligent knitted electrochromic fiber are realized, and the problem to be solved is urgently needed.
Disclosure of Invention
In order to solve at least one of the above problems, the present invention is directed to developing flexible electrochromic liquid crystal fibers, which not only expand the non-display application field of liquid crystal, but also improve the production technology of electrochromic textiles, and meet the diversified demands of the market. The invention provides a preparation and production process of an electrochromic liquid crystal fiber with a coaxial sandwich structure, which adopts a coaxial microfluid spinning method to prepare an electrochromic liquid crystal fiber which takes a black conductive polymer fiber as an inner conductive layer, a transparent metal nanowire fiber layer as an outer conductive layer and polymer dispersed cholesteric liquid crystal as an electrochromic layer, and explores a process method for continuously producing electrochromic textile devices by preparing large-size electrical stimulation response electrochromic liquid crystal fibers.
The invention overcomes the difficulty that the prior art can not construct a large-scale and long-term stable electrochromic liquid crystal system under the condition of no external electrode (ITO glass and the like) by a method for preparing the electrochromic liquid crystal fiber by microfluid rectifying spinning; on the basis of single axial shear force of a wet spinning injection flow, the horizontal polymer flow is coaxially introduced to provide radial shear force, and cholesteric liquid crystal inside the middle layer is guided to assemble to form a uniform and flat electrochromic liquid crystal layer.
It is a first object of the present invention to provide a method for preparing an electrochromic liquid-crystalline fiber comprising the steps of:
(1) preparation of transparent conductive outer layer injection 1: dispersing sodium alginate, glucose and metal nanowires in a solvent, and uniformly mixing to obtain an injection 1;
(2) preparation of black conductive inner layer injection 2: dispersing sodium alginate, glucose and black conductive polymer in a solvent, and uniformly mixing to obtain an injection 2;
(3) preparation of electrochromic liquid crystal interlayer injection 3: dispersing sodium alginate, glucose and cholesteric liquid crystal in a solvent, and mixing uniformly to obtain an injection 3;
(4) salt solution preparation to drive polymer outward migration: preparing a calcium chloride coagulating bath; specifically, calcium chloride is added into water to be uniformly dispersed to obtain a coagulating bath containing a large amount of calcium ions;
(5) injecting the injection 1, the injection 2 and the injection 3 into a calcium chloride coagulating bath through coaxial injectors, and leading the sodium alginate to migrate outwards under the guidance of calcium ions to form polymer nanofluid, namely obtaining the electrochromic liquid crystal microfiber with a coaxial structure.
In one embodiment of the present invention, in the injection solution 1 described in step (1), the concentration of sodium alginate in the solvent is 0.2 to 1.5 wt%, the concentration of glucose in the solvent is 1 to 10 wt%, and the concentration of metal nanowires in the solvent is 0.05 to 0.3 wt%.
In one embodiment of the present invention, in the injection solution 2 described in the step (2), the concentration of sodium alginate is 0.2 to 1.5 wt% with respect to the solvent, the concentration of glucose is 1 to 10 wt% with respect to the solvent, and the concentration of the black conductive polymer is 0.05 to 0.3 wt% with respect to the solvent.
In one embodiment of the present invention, in the injection solution 3 described in step (3), the concentration of sodium alginate in the solvent is 0.2 to 1.5 wt%, the concentration of glucose in the solvent is 1 to 10 wt%, and the concentration of cholesteric liquid crystal phase in the solvent is 60 to 90 wt%.
In one embodiment of the invention, the solvent in the injection 1, the injection 2 and the injection 3 is water or a PVA aqueous solution, wherein the concentration of the PVA aqueous solution is 2-10 wt%.
In one embodiment of the present invention, the cholesteric liquid crystal in the step (3) is one or more of red cholesteric liquid crystal, yellow cholesteric liquid crystal, and blue cholesteric liquid crystal.
In one embodiment of the present invention, the metal nanowires of step (1) comprise one or more of silver nanowires, copper nanowires, and aluminum nanowires; the metal nanowire has a high length-diameter ratio, the length is about 20-50 microns, and meanwhile, the metal nanowire has good conductivity.
In one embodiment of the present invention, the black conductive polymer in step (2) includes one or more of graphene polymer, polythiophene polymer, and conductive carbon black polymer; further preferred is sodium poly (3,4 ethylenedioxythiophene) polystyrene sulfonate; the black conductive polymer has excellent water-soluble dispersibility and good conductive characteristics.
In one embodiment of the present invention, the cholesteric liquid crystal in step (3) is one or more cholesteric liquid crystals, and the cholesteric phase includes one or more of cholesterol acetate, cholesterol propionate, cholesterol n-butyrate, cholesterol pelargonate, cholesterol oleate, cholesterol linoleate, cholesterol benzoate, cholesterol cinnamate, cholesterol ethyl carbonate, cholesterol oleyl carbonate, cholesterol isostearyl carbonate, cholesterol butenyl crotonate, cholesterol alkenyl carbonate, and chlorinated cholesterol.
In one embodiment of the present invention, the cholesteric liquid crystal in the step (3) has a radial topology and an axial wheatear topology inside, which has bistable electrochromic characteristics under the action of an electric field.
In an embodiment of the invention, the cholesteric liquid crystal in the step (3) needs to be heated to a temperature higher than a clear point (i.e., heated to a state where the mixture is dissolved and transparent) before use, stirred for 1 to 3 hours, cooled to a temperature at which the cholesteric liquid crystal is colored or turbid, heated to be just transparent, and stirred at a constant temperature for 2 to 5 hours.
In one embodiment of the present invention, the molar concentration of calcium chloride in the calcium chloride coagulation bath in step (4) is 10 to 100mM, preferably 50 to 80mM, and more preferably 50 mM; when the concentration of calcium chloride is too low, the internal polymer sodium alginate lacks sufficient traction force, and a stable and smooth hydrogel skin is difficult to form at the interface; the concentration of calcium chloride is too high, and the excessive calcium ions are crosslinked with sodium alginate, so that the liquid crystal fiber is not easy to take out from the receiving liquid.
In one embodiment of the present invention, the preparation method of the calcium chloride coagulation bath in step (4) comprises: adding calcium chloride into water, and performing ultrasonic dispersion uniformly to obtain a coagulating bath containing a large amount of calcium ions.
In one embodiment of the invention, the injection 1, the injection 2 and the injection 3 in the step (5) have a mass ratio of 5-30: 100: 5 to 30.
In one embodiment of the present invention, the injection speed in step (5) is 0.5-4 mL/min; the injection speed was controlled by a peristaltic pump; preferably, the injection speed is 1-2 mL/min; further preferably, the injection rate is 15 mL/min.
In one embodiment of the present invention, the conditions for the coagulation of the fibers in step (5) are: the temperature is 20-30 ℃, and the time is 3-8 min.
In one embodiment of the invention, the sodium alginate used in the preparation is of AR grade and is 90% pure.
In one embodiment of the invention, the mass percent concentration of sodium alginate used in the steps (1) to (3) in the preparation process is 0.2-1.5 wt%, and when the concentration of sodium alginate is too low, the liquid crystal microfiber is not easy to form a stable and smooth hydrogel skin; the concentration of sodium alginate is too high, and the viscosity is too high, so that the rapid arrangement and assembly of the cholesteric liquid crystal layer are not facilitated.
The second object of the invention is the electrochromic liquid crystal fiber prepared by the method of the invention.
The third purpose of the invention is to provide an electrochromic liquid crystal fiber, which has a three-layer structure, wherein the outer layer is a metal nanowire fiber layer, the middle layer is a cholesteric liquid crystal layer, and the inner layer is a black conductive fiber layer.
In one embodiment of the invention, the metal nanowire fiber layer is obtained by dispersing and uniformly mixing sodium alginate, glucose and metal nanowires in water; wherein the mass percentage concentration of sodium alginate relative to water is 0.2-1.5 wt%, the mass percentage concentration of glucose relative to water is 1-10 wt%, and the mass percentage concentration of metal nanowires relative to water is 0.05-0.3 wt%.
In one embodiment of the invention, the black conductive fiber layer is obtained by dispersing and uniformly mixing sodium alginate, glucose and a black conductive polymer in water; wherein the mass percentage concentration of sodium alginate relative to water is 0.2-1.5 wt%, the mass percentage concentration of glucose relative to water is 1-10 wt%, and the mass percentage concentration of black conductive polymer relative to water is 0.05-0.3 wt%.
In one embodiment of the invention, the cholesteric liquid crystal layer is obtained by adding cholesteric liquid crystal, sodium alginate and glucose into water and uniformly mixing; wherein the mass percentage concentration of sodium alginate relative to water is 0.2-1.5 wt%, the mass percentage concentration of glucose relative to water is 1-10 wt%, and the mass percentage concentration of cholesteric phase liquid relative to water is 60-90 wt%.
In one embodiment of the invention, the electrochromic liquid crystal fiber is obtained by co-axial spinning.
In one embodiment of the invention, the mass ratio of the metal nanowire fiber layer, the black conductive fiber layer and the cholesteric liquid crystal layer is 5-30: 100: 5 to 30.
The fourth purpose of the invention is the application of the electrochromic liquid crystal fiber in military protection concealing materials, flexible displays, anti-counterfeiting marks or safety warnings or artistic ornaments.
The invention has the beneficial effects that:
(1) the invention prepares the coaxial electrochromic liquid crystal fiber by microfluid rectification, introduces a horizontal polymer flow to provide a radial shearing force on the basis of single coaxial shearing force of a wet spinning injection flow, and guides an internal polymer dispersed (cholesteric) liquid crystal layer to assemble to form a chiral liquid crystal fiber layer. The method is simple to operate and easy for large-scale production, and the prepared liquid crystal microfiber has a long-range ordered structure, a stable topological configuration and a controllable optical appearance and has wide application potential in basic soft substance research and specific optical sensing and identification.
(2) In the method, the transparent metal nanowire fiber and the black conductive fiber are used as self-contained parallel electrodes and are used for protecting the middle cholesteric phase liquid crystal from being polluted by the external environment and fixing the relative positions. The electrochromic liquid crystal fiber prepared by the method can reversibly change color under the stimulation of an electric field, can realize a continuous stable state of a certain color change state under the condition of power failure, has gorgeous and changeable color, low driving voltage which is lower than 23.9V (lower than the safe voltage of a human body), good solvent resistance and water resistance, can still keep the original bistable electrochromic performance after weaving processing, and can meet the requirements of people on individuation and diversity of liquid crystal color development in flexible display and intelligent textiles. The electrochromic liquid crystal fiber prepared by the method has good physical, chemical and optical properties and wide application prospect.
(3) The chiral cholesteric liquid crystal array has high content, so that the liquid crystal microfiber displays single color in a natural light visual field, displays uniform interference color in polarized light, has low driving voltage and better meets the textile taking conditions.
(4) The electrochromic liquid crystal fiber which is good in light transmittance, high in mechanical strength and resistant to chemical corrosion is prepared by using cholesteric liquid crystal, and meanwhile, the fiber needs to meet the requirements of lower driving voltage and colorful electrochromic capacity and has the bistable characteristic of zero-electric-field color development.
(5) The invention researches a specific preparation method of the electrochromic liquid crystal fiber, and the electrochromic liquid crystal fiber without an additional electrode is prepared by screening a proper electrode material and liquid crystal ratio and adopting a coaxial microfluid spinning method; the composition proportion and the shape distribution of the cholesteric liquid crystal material play a crucial role in bistable state display, and in the experimental process, it is found that not all cholesteric liquid crystals can be added to realize fiber bistable state color development. The bistable electrochromic selection conditions mainly include two aspects: firstly, calcium alginate (sodium alginate is crosslinked with calcium chloride in coagulation bath to form calcium alginate) and glucose base material have certain binding force with cholesteric liquid crystal, and the orientation distribution state of cholesteric liquid crystal can be fixed in the fiber forming process, so that the bistable display effect is achieved; secondly, the interaction force between the calcium alginate and glucose materials and the cholesteric liquid crystal phase is not too strong, otherwise the response performance of the liquid crystal under an electric field is affected, and the color change effect is lost. Multiple experiments of the inventor prove that only the thickness of the cholesteric liquid crystal intermediate layer is at least more than 20 micrometers, and the ratio of sodium alginate to glucose base material in the cholesteric liquid crystal is about 5-15 wt% so as to meet the bistable electrochromic characteristic.
Drawings
FIG. 1 is a coaxial electrochromic liquid crystal fiber structure and stimulus response mechanism in which (a) there is no electric field; (b) there is an electric field.
Detailed Description
The following description of the preferred embodiments of the present invention is provided for the purpose of better illustrating the invention and is not intended to limit the invention thereto. The sodium alginate powder used below was of AR grade, 90% pure, purchased from shanghai alatin biochemical science and technology ltd; glucose powder is AR grade, molecular weight: 180.16, available from Shanghai Aladdin Biotechnology, Inc.
The test method comprises the following steps:
and (3) testing the photoelectric performance: fixing the prepared electrochromic liquid crystal fibers on a rigid substrate, driving the device by adopting a direct-current steady-state power supply, and verifying the electrochromic phenomenon of the display device; the display effect and the electro-optic performance of the liquid crystal fiber device are respectively characterized: the display effect of the device under voltage driving is recorded by real-time photography; and (3) testing an incident light transmittance curve of the device under different external voltages by using the central reflection wavelength of the device in a color development state as a fixed detection wavelength by using a fiber optic spectrometer. During the test, black inner layer fibers were used as blank reference.
The method for testing the loading capacity of the fiber liquid crystal core material comprises the following steps: weighing electrochromic liquid crystal fibers with the weight a, grinding the electrochromic liquid crystal fibers, dissolving the fibers by using an ethanol solvent, centrifugally collecting lower-layer precipitate, and weighing the lower-layer precipitate as b, wherein the calculation formula of the loading capacity c of the fiber liquid crystal core material is as follows:
water resistance test method and solvent resistance test method: referring to GB/T5211.5-2008, the solvents selected include ethanol, ethylene glycol, acetone.
Example 1
A method for preparing electrochromic liquid crystal fibers by a coaxial microfluid spinning method comprises the following steps:
(1) preparation of transparent conductive outer layer injection 1: dispersing 0.05g of sodium alginate powder, 0.5g of glucose powder and 1.5g of silver nanowires (with the length and the diameter of 10 mu m and 60nm) (Sigma company) in 10mL of water, and magnetically stirring for 10min to prepare a uniform injection 1, wherein the mass fraction of the silver nanowires relative to the water is 0.15 wt%;
(2) preparation of black conductive inner layer injection 2: dispersing 0.05g of sodium alginate powder, 0.5g of glucose powder and 0.15g of poly (3, 4-ethylenedioxythiophene) -poly (styrenesulfonic acid) (Shanghai test Co., Ltd.) in 10mL of water, and magnetically stirring for 10min to prepare a uniform injection 2, wherein the mass fraction of the poly (3, 4-ethylenedioxythiophene) -poly (styrenesulfonic acid) relative to the water is 0.015 wt%;
(3) preparation of electrochromic liquid crystal interlayer injection 3: adding 0.05G of sodium alginate powder, 0.5G of glucose powder and 9G of red cholesteric liquid crystal (U10-006G-680, Shijia Chengxi Yonghua company) into 10mL of water, and magnetically stirring for 10min to prepare uniform injection 3, wherein the mass fraction of the red cholesteric liquid crystal phase relative to the water is 90 wt%;
(4) salt solution preparation to drive polymer outward migration: adding 2.775g anhydrous calcium chloride (Shanghai Aladdin Biotechnology Co., Ltd.) into 500mL water, and performing ultrasonic treatment under 100W ultrasonic condition for 5min to obtain 50mM calcium chloride coagulation bath;
(5) preparing electrochromic liquid crystal fibers: injecting the injection 1, the injection 2 and the injection 3 obtained in the steps (1) to (3) into the calcium chloride coagulating bath obtained in the step (4) through an injector to obtain the electrochromic liquid crystal fiber with a chiral cholesteric array, a long-range ordered internal structure, stable liquid crystal configuration and controllable optical appearance; wherein the injection speed of the syringe is controlled to be 1.5mL/min by a peristaltic pump.
The prepared electrochromic liquid crystal fiber was subjected to a photoelectric property test (see table 1) and a water and solvent resistance test (see table 2).
FIG. 1 is a coaxial electrochromic liquid crystal fiber structure and stimulus response mechanism in which (a) there is no electric field; (b) there is an electric field. As can be seen from fig. 1: when no electric field is applied, the liquid crystal layer is in the color of the liquid crystal itself (red in example 1), and the liquid crystal layer changes color to a transparent color after the electric field is applied, thereby realizing electrochromic.
Example 2
Adjusting 90 wt% of red cholesteric liquid crystal in the injection 3 of example 1 to 80 wt% of blue cholesteric liquid crystal (U10-006G-480, Shijia Cheng Yonghua Co., Ltd.), and using copper nanowires as the metal nanowires in the injection 1, wherein the mass fraction of the copper nanowires is 0.3 wt%; the electrochromic liquid crystal microfiber was prepared by following the same preparation procedure as in example 1.
The electrochromic liquid crystal fiber prepared above was subjected to a photoelectric property test (see table 1) and a water and solvent resistance test (see table 2). From the test results it can be seen that: the thickness of the liquid crystal layer of the electrochromic liquid crystal fiber obtained in comparative example 1 becomes thinner as the concentration of the cholesteric liquid crystal decreases, and the required electrochromic driving voltage increases.
Example 3
Preparation of injection 3 of example 1 90 wt% of red cholesteric liquid crystal was adjusted to 70 wt% of yellow cholesteric liquid crystal (U10-006G-580, Shijia Cheng Yonghua Co., Ltd.) and electrochromic liquid crystal microfibers were prepared by the same preparation procedure as in example 1.
The prepared electrochromic liquid crystal fiber was subjected to a photoelectric property test (see table 1) and a water and solvent resistance test (see table 2). From the test results it can be seen that: the thickness of the liquid crystal layer of the electrochromic liquid crystal fiber obtained in comparative example 1 continued to be thinner and the required electrochromic driving voltage continued to be higher as the cholesteric liquid crystal concentration continued to be lower.
Example 4
Preparation of injection 3 of example 1 to 90 wt% of red cholesteric liquid crystal was adjusted to 60 wt% of red cholesteric liquid crystal (U10-006G-680, Shijia Cheng Yonghua Co., Ltd.), and electrochromic liquid crystal microfibers were prepared by the same preparation procedure as in example 1.
The prepared electrochromic liquid crystal fiber was subjected to a photoelectric property test (see table 1) and a water and solvent resistance test (see table 2). From the test results it can be seen that: the thickness of the liquid crystal layer of the electrochromic liquid crystal fiber obtained in comparative example 1 continued to be thinner and the required electrochromic driving voltage continued to be higher as the cholesteric liquid crystal concentration continued to be lower.
Comparative example 1
Electrochromic liquid crystal microfibers were prepared by the same preparation procedure as in example 1 except that 90 wt% of red cholesteric liquid crystal in injection solution 3 of example 1 was adjusted to 40 wt% of red cholesteric liquid crystal (U10-006G-680, Shijia Chengxi Yonghua Co., Ltd.) and sodium alginate was used in an amount exchanged for glucose.
The prepared electrochromic liquid crystal fiber was subjected to a photoelectric property test (see table 1) and a water and solvent resistance test (see table 2). The electrochromic liquid crystal fiber obtained in example 1 has high mechanical strength, excellent ductility and uniform color rendering property, the electrochromic liquid crystal fiber obtained in comparative example 1 has low mechanical strength, the fiber elongation is 1.5%, and the tensile stress is 4MPa, which is much lower than the mechanical property of the electrochromic liquid crystal fiber obtained in example 1; and sodium ions in the injection liquid can continuously migrate into the receiving liquid, and finally, the calcium chloride coagulation bath is also crosslinked, so that the liquid crystal fiber cannot be taken out of the receiving liquid. Meanwhile, the electrochromic driving voltage of the fiber is increased to be higher than the human body safety voltage (less than 36V) due to the reduction of the liquid crystal ratio.
Comparative example 2
Electrochromic liquid crystal fibers were produced by the same production procedure as in example 1 except that the calcium chloride coagulation bath in step (4) of example 1 was changed to one using anhydrous ethanol (95%) as the coagulation bath.
The liquid crystal fiber prepared as described above was subjected to a photoelectric property test (see table 1) and a water and solvent resistance test (see table 2). From the test results it can be seen that: the electrochromic liquid crystal fiber obtained in example 1 had high mechanical strength, excellent ductility and uniform color development, and the liquid crystal fiber obtained in comparative example 2 had low mechanical strength and the surface of the liquid crystal fiber was not smooth, resulting in uneven color development of the liquid crystal. In the absolute ethyl alcohol coagulating bath, the sodium alginate in the injection is precipitated and hardened, and the water in the liquid crystal fiber migrates to the absolute ethyl alcohol, so that the surface of the liquid crystal fiber is stressed unevenly, a rough surface is formed, the forming cannot be carried out, and the electrochromic property is avoided.
TABLE 1 electro-optical Properties of the electrochromic liquid Crystal fiber Material
Note: "-" indicates that no fibers could be formed.
TABLE 2 Water and solvent resistance of electrochromic liquid-crystalline fiber materials
Example 5 Red cholesteric liquid Crystal concentration optimization
The mass fraction of the red cholesteric liquid crystal phase with respect to water in injection 3 of example 1 was adjusted to 60% and 80%, and electrochromic liquid crystal microfibers were prepared by the same preparation procedure as in example 1.
Comparative example 3
The mass fraction of the red cholesteric liquid crystal phase with respect to water in injection 3 of example 1 was adjusted to 50% and 95%, and electrochromic liquid crystal microfibers were prepared by the same preparation procedure as in example 1.
The electrochromic liquid crystal fibers prepared in example 5 and comparative example 3 were subjected to the photoelectric property test (see table 3) and the water and solvent resistance test (see table 4).
TABLE 3 electro-optical Properties of the electrochromic liquid Crystal fiber Material
TABLE 4 Water and solvent resistance of electrochromic liquid-crystalline fiber materials
Example 6
Electrochromic liquid-crystal microfibers were prepared by the same preparation procedure as in example 1 except that the mass concentrations of sodium alginate with respect to water in steps (1) to (3) of example 1 were adjusted to 0.2%, 1%, and 1.5%.
Comparative example 4
Electrochromic liquid crystal microfibers were prepared by the same preparation procedure as in example 1 except that the mass concentration of sodium alginate with respect to water in steps (1) to (3) of example 1 was adjusted to 0.01% and 20%.
The electrochromic liquid crystal fibers prepared in example 6 and comparative example 4 were subjected to the photoelectric property test (see table 5) and the water and solvent resistance test (see table 6).
TABLE 5 electro-optical Properties of the electrochromic liquid Crystal fiber Material
Note: "-" indicates that it is not conductive, i.e., there is no driving voltage.
TABLE 6 Water and solvent resistance of electrochromic liquid-crystalline fiber materials
Example 7
Electrochromic liquid crystal microfibers were prepared by the same preparation procedure as in example 1 except that the concentration of glucose powder in water was adjusted to 1% and 10% by mass in steps (1) to (3) of example 1.
Comparative example 5
Electrochromic liquid crystal microfibers were prepared by the same preparation procedure as in example 1 except that the mass concentration of glucose powder relative to water in steps (1) to (3) of example 1 was adjusted to 0.05% and 50%.
The electrochromic liquid crystal fibers prepared in example 7 and comparative example 5 were subjected to the photoelectric property test (see table 7) and the water and solvent resistance test (see table 8).
TABLE 7 electro-optical Properties of the electrochromic liquid Crystal fiber Material
Note: "-" indicates that it is not conductive, i.e., there is no driving voltage.
TABLE 8 Water and solvent resistance of electrochromic liquid-crystalline fiber materials
Comparative example 6
Electrochromic liquid crystal fibers were produced by the same production procedure as in example 1 except that the calcium chloride coagulation bath in step (4) of example 1 was changed to a methanol aqueous solution (5 wt%) as the coagulation bath.
As a result, it was found that no fibers could be formed at all.
Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A method of making an electrochromic liquid crystal fiber comprising the steps of:
(1) preparation of transparent conductive outer layer injection 1: dispersing sodium alginate, glucose and metal nanowires in a solvent, and uniformly mixing to obtain an injection 1;
(2) preparation of black conductive inner layer injection 2: dispersing sodium alginate, glucose and black conductive polymer in a solvent, and uniformly mixing to obtain an injection 2;
(3) preparation of electrochromic liquid crystal interlayer injection 3: dispersing sodium alginate, glucose and cholesteric liquid crystal in a solvent, and mixing uniformly to obtain an injection 3;
(4) salt solution preparation to drive polymer outward migration: preparing a calcium chloride coagulating bath; specifically, calcium chloride is added into water to be uniformly dispersed to obtain a coagulating bath containing a large amount of calcium ions;
(5) injecting the injection 1, the injection 2 and the injection 3 into a calcium chloride coagulating bath through coaxial injectors, and leading the sodium alginate to migrate outwards under the guidance of calcium ions to form polymer nanofluid, namely obtaining the electrochromic liquid crystal microfiber with a coaxial structure.
2. The method according to claim 1, wherein the injection solution 1 of step (1) comprises 0.2 to 1.5 wt% of sodium alginate, 1 to 10 wt% of glucose and 0.05 to 0.3 wt% of metal nanowires.
3. The method according to claim 1 or 2, wherein the injection solution 2 in the step (2) has a concentration of 0.2 to 1.5 wt% of sodium alginate with respect to the solvent, a concentration of 1 to 10 wt% of glucose with respect to the solvent, and a concentration of 0.05 to 0.3 wt% of the black conductive polymer with respect to the solvent.
4. The method according to any one of claims 1 to 3, wherein the concentration of sodium alginate in the injection solution 3 in the step (3) is 0.2 to 1.5 wt% based on the mass of the solvent, the concentration of glucose in the injection solution is 1 to 10 wt% based on the mass of the solvent, and the concentration of the cholesteric liquid crystal phase in the injection solution is 60 to 90 wt% based on the mass of the solvent.
5. The method according to any one of claims 1 to 4, wherein the mass ratio of the injection solution 1, the injection solution 2 and the injection solution 3 in the step (5) is 5 to 30: 100: 5 to 30.
6. The method according to any one of claims 1 to 5, wherein the injection rate in step (5) is 0.5 to 4 mL/min.
7. The method according to any one of claims 1 to 6, wherein the molar concentration of calcium chloride in the calcium chloride coagulation bath in the step (4) is 10 to 100 mM.
8. An electrochromic liquid crystal fiber prepared by the method of any one of claims 1 to 7.
9. An electrochromic liquid crystal fiber is characterized in that the structure of the electrochromic liquid crystal fiber is a three-layer structure, the outer layer is a metal nanowire fiber layer, the middle layer is a cholesteric liquid crystal layer, and the inner layer is a black conductive fiber layer; the mass ratio of the metal nanowire fiber layer to the black conductive fiber layer to the cholesteric liquid crystal layer is 5-30: 100: 5 to 30.
10. Use of the electrochromic liquid crystal fibers of claim 8 or 9 in military protective concealment materials, flexible displays, security signs or safety warnings or art ornaments.
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| IT202100012038A1 (en) * | 2021-05-12 | 2022-11-12 | Technocell Ag | ELECTROCHROMIC TEXTILE THREAD AND RELATED FABRICS |
| CN115247291A (en) * | 2021-09-15 | 2022-10-28 | 青岛大学 | Electroluminescent fiber and preparation method and application thereof |
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