Blue-phase liquid crystal polymer fiber capable of changing color in mechanical response as well as preparation method and application of blue-phase liquid crystal polymer fiber

Abstract

The invention relates to the technical field of mechanochromic materials, and discloses a blue-phase liquid crystal polymer fiber capable of changing color through mechanical response and a preparation method and application of the blue-phase liquid crystal polymer fiber. The blue-phase liquid crystal polymer fiber with the mechanical response color changing function is of a skin-core structure, a skin layer is a blue-phase liquid crystal layer, and a core layer is a polymer fiber monofilament; and the blue-phase liquid crystal polymer fiber can generate color change response under stress change. When an external force is applied to the blue-phase liquid crystal polymer fiber, the lattice constant of the blue-phase liquid crystal is changed, so that the reflection wavelength is changed and the color is changed, and the blue-phase liquid crystal polymer fiber has a reversible color change behavior due to a stable polymer network structure; the preparation method disclosed by the invention is simple in process, and a blue phase structure with a good lattice structure and a large plate can be obtained through rapid cooling; the prepared blue-phase liquid crystal polymer fiber is good in processability and high in performance, and has very good application potential in the fields of sensors, display, stealth and anti-counterfeiting.

Description

Technical Field

[0001] The present application relates to the technical field of mechanochromic materials, and in particular to a blue phase liquid crystal polymer fiber that changes color in response to mechanical forces, and a preparation method and application thereof. Background Art

[0002] In nature, many organisms, such as chameleons, have gradually adapted to their surroundings during a long evolutionary process and developed the ability to change their body color according to external conditions. Inspired by this biological characteristic, researchers have developed a series of intelligent color-changing materials and devices, which are widely used in various fields such as flexible robots, anti-counterfeiting, camouflage, invisibility and display.

[0003] The blue phase is a special phase in a narrow temperature range between the cholesteric phase and the isotropic phase of liquid crystal. It is considered to be one of the most promising photonic crystal materials due to its unique self-assembled periodic cubic lattice structure, three-dimensional photonic band gap in the visible light band, and excellent external field response characteristics. Blue phase liquid crystal fiber is one of the main applications of blue phase liquid crystal. At present, it is mainly prepared by processing the prepolymer liquid crystal into fiber morphology through microtube injection molding, syringe extrusion molding or spinning molding, and then slowly cooling the prepolymer liquid crystal fiber to blue phase liquid crystal fiber under strict control of the program.

[0004] However, the temperature range of blue phase liquid crystal is narrow and it is highly sensitive to temperature. It is necessary to slowly cool down the liquid crystal polymer above the clearing point and strictly control the cooling rate, which makes the existing blue phase liquid crystal fiber preparation process complicated and has poor processability. Summary of the invention

[0005] The present application provides a blue phase liquid crystal polymer fiber that changes color in mechanical response, and a preparation method and application thereof, aiming to solve the problem of complex preparation process of the existing blue phase liquid crystal fiber.

[0006] In order to achieve the above objectives, the present application adopts the following technical solutions.

[0007] In a first aspect of the present application, a blue phase liquid crystal polymer fiber that changes color in mechanical response is provided, which has a skin-core structure, wherein the skin layer is a blue phase liquid crystal layer, and the core layer is a polymer fiber monofilament; the blue phase liquid crystal polymer fiber can change color in response to stress changes.

[0008] Preferably, the blue phase liquid crystal layer comprises the following raw materials in percentage by mass:

[0009] Nematic liquid crystal 65-80%, chiral compound 3.5-5%, chain extender 5-15%, cross-linking agent 10-20%, photoinitiator 1-5% and inhibitor 0.1-1.5%;

[0010] The chiral compounds include non-polymerizable chiral compounds and polymerizable chiral compounds;

[0011] The polymer fibers include polyurethane fibers.

[0012] Further preferably, the nematic liquid crystal includes at least one of C6M, RM23, RM82, RM257, C4M or C3M;

[0013] The non-polymerizable chiral compound is at least one of R5011, S5011, R811, S811, R1011, S1011, R3011, S3011 or CB15; the polymerizable chiral compound is DK756;

[0014] The chain extender is benzoic acid or its derivatives;

[0015] The cross-linking agent includes any one of EDDET, PETMP, HDT or SH-PEG2-SH;

[0016] The photoinitiator includes at least one of benzoin dimethyl ether, benzoin diethyl ether, PI1173, PI184, TPO, PBZ or PI819;

[0017] The polymerization inhibitor is p-methoxyphenol.

[0018] The second aspect of the present application provides a method for preparing a blue phase liquid crystal polymer fiber with mechanical response color change, comprising:

[0019] S1, dissolving the raw materials of the blue phase liquid crystal layer in a solvent to prepare a solution, heating the solution to completely volatilize the solvent in the solution, and raising the temperature to a clearing point of the blue phase liquid crystal to obtain a polymer liquid crystal prepolymer solution;

[0020] S2, passing the polymer fiber monofilament through the polymer liquid crystal prepolymer solution to obtain a precursor fiber; heating the precursor fiber to make the polymer liquid crystal prepolymer solution reach an isotropic state, and then quickly cooling the temperature of the precursor fiber to room temperature;

[0021] S3, the precursor fiber after cooling is polymerized by ultraviolet light to obtain a blue phase liquid crystal polymer fiber with mechanical response color change.

[0022] Preferably, the solvent includes at least one of ethanol, acetone, dichloromethane and dimethylformamide; and the polymer fiber monofilament is a polyurethane fiber monofilament.

[0023] Preferably, the heating temperature in S1 is 40-60°C.

[0024] Preferably, the clearing point of the blue phase liquid crystal is 85-90°C.

[0025] Preferably, the cooling rate in S2 is 50-500°C / min.

[0026] Preferably, the ultraviolet light energy density of the ultraviolet light polymerization is 0.3 to 25 mw / cm2, and the polymerization time is 0.1 to 0.5 h.

[0027] The third aspect of the present application provides the application of the above-mentioned mechanically responsive color-changing blue phase liquid crystal polymer fiber or the mechanically responsive color-changing blue phase liquid crystal polymer fiber prepared by the above-mentioned preparation method in the fields of sensors, displays, stealth or anti-counterfeiting.

[0028] Compared with the prior art, the beneficial effects of this application are:

[0029] When an external force is applied to the blue phase liquid crystal polymer fiber of the present application, the lattice constant of the blue phase liquid crystal changes, thereby causing the change of the reflected wavelength to change color, and because it has a stable polymer network structure, it has a reversible color change behavior. In the blue phase liquid crystal of the present application, the liquid crystal molecules form a three-dimensional cubic lattice structure (similar to the crystal structure, but with the fluidity of liquid crystal), and the coherence length is short, with a fast response time, and its response time can be accurately adjusted by changing the stress; the periodicity of the three-dimensional photonic crystal structure of the blue phase liquid crystal is equivalent to the wavelength of light, so it can selectively reflect light through Bragg reflection. In addition, the photonic band gap of the blue phase liquid crystal of the present application is narrow, and its color rendering is high.

[0030] The preparation method of the present application is simple in process, and a blue phase structure with good lattice structure and large plates can be obtained by rapid cooling. The prepared blue phase liquid crystal polymer fiber has good processability and high performance, and has very good application potential in the fields of sensors, displays, stealth and anti-counterfeiting. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 The blue phase liquid crystal polymer prepared in Example 1 is a physical image after rapid cooling, a polarizing microscope image and a reflection spectrum image;

[0033] Figure 2 This is a diagram showing the mechanical response color change effect of the blue phase liquid crystal polymer prepared in Example 1;

[0034] Figure 3 The blue phase liquid crystal polymer prepared in Comparative Example 1 is a physical image after rapid cooling, a polarizing microscope image and a reflection spectrum image;

[0035] Figure 4 This is a diagram showing the mechanical response color change effect of the blue phase liquid crystal polymer prepared in Comparative Example 1;

[0036] Figure 5 The actual image, polarizing microscope image and reflection spectrum image of the blue phase liquid crystal polymer prepared in Comparative Example 2 after slow cooling;

[0037] Figure 6 This is a diagram showing the mechanical response color change effect of the blue phase liquid crystal polymer prepared in Comparative Example 2. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0039] In the following description of this embodiment, the terms "include", "comprising", "having" and "containing" are all open terms, meaning including but not limited to.

[0040] In the following description of this embodiment, the term "and / or" is used to describe the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, B exists alone, and A and B exist at the same time. A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0041] In the following description of this embodiment, the term "at least one" refers to one or more, and "plurality" refers to two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c", can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.

[0042] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0043] Those skilled in the art should understand that in the following description of the embodiments of the present application, the order of serial numbers does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0044] Those skilled in the art will appreciate that the numerical ranges in the embodiments of the present application are to be construed as specifically disclosing each intermediate value between the upper and lower limits of the scope. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present application. The upper and lower limits of these smaller ranges may be independently included or excluded in the scope.

[0045] Unless otherwise specified, the technical / scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which this application belongs. Although this application only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of this application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0046] In a first aspect, the present application provides a blue phase liquid crystal polymer fiber that changes color in mechanical response, which has a skin-core structure, wherein the skin layer is a blue phase liquid crystal layer, and the core layer is a polymer fiber monofilament; the blue phase liquid crystal polymer fiber can change color in response to stress changes.

[0047] In the blue phase liquid crystal polymer fiber of the present application, the blue phase liquid crystal layer includes the following raw materials in percentage by mass: 65-80% nematic phase liquid crystal, 3.5-5% chiral compound, 5-15% chain extender, 10-20% cross-linker, 1-5% photoinitiator and 0.1-1.5% inhibitor; the polymer fiber is preferably polyurethane fiber.

[0048] In the present application, the chiral compound includes a non-polymeric chiral compound and a polymerizable chiral compound. Specifically, the non-polymeric chiral compound is at least one of R5011, S5011, R811, S811, R1011, S1011, R3011, S3011 or CB15; the polymerizable chiral compound is DK756. In the present application, by changing the dosage ratio of the polymerizable chiral compound to the non-polymeric chiral compound, the density of the blue phase liquid crystal polymer network can be adjusted, thereby adjusting the mechanical response speed of the blue phase liquid crystal polymer fiber. In the present application, the chiral compound is preferably a mixture of DK756 and R5011, wherein the chemical structure of DK756 is as follows:

[0049]

[0050] The chemical structure of R5011 is shown below:

[0051]

[0052] In the present application, the nematic liquid crystal is a polymerizable liquid crystal, which can form a liquid crystal polymer network through photopolymerization reaction. The nematic liquid crystal can be selected from at least one of C6M, RM23, RM82, RM257, C4M or C3M. The preferred nematic liquid crystal in the present application is C6M, and its chemical structure is as follows:

[0053]

[0054] In the present application, the chain extender and the thiol crosslinker undergo Michael addition reaction to stabilize the polymer blue phase liquid crystal, broaden the temperature range of the blue phase liquid crystal, and improve the flexibility of the three-dimensional network structure of the blue phase liquid crystal. In the present application, the chain extender is benzoic acid or its derivatives, such as 4-(6-(acryloyloxy)hexyloxy)benzoic acid; the present application preferably uses 4-(6-(acryloyloxy)hexyloxy)benzoic acid, and its chemical structure is shown below:

[0055]

[0056] The cross-linking agent can be any one of EDDET, PETMP, HDT or SH-PEG2-SH; the preferred cross-linking agent in this application is EDDET, whose chemical structure is shown below:

[0057]

[0058] In the present application, the photoinitiator includes at least one of benzoin dimethyl ether, benzoin diethyl ether, PI1173, PI184, TPO, PBZ or PI819; preferably benzoin diethyl ether.

[0059] The polymerization inhibitor is used to prevent the C6M in the polymer liquid crystal prepolymer solution and the precursor fiber from self-reacting and reducing the flexibility of the polymer network. In the present application, the polymerization inhibitor is p-methoxyphenol.

[0060] The blue phase liquid crystal polymer fiber of the present application has an elastic skin-core fiber structure. When external force is applied, the lattice constant of the blue phase liquid crystal changes, resulting in a change in the reflection wavelength and discoloration. Because it has a stable polymer network structure, it has reversible discoloration behavior.

[0061] In the blue phase liquid crystal of the present application, the liquid crystal molecules form a three-dimensional cubic lattice structure (similar to the crystal structure, but with the fluidity of liquid crystal), and the coherence length is short, with a fast response time, and its response time can be accurately adjusted by changing the stress; the periodicity of the three-dimensional photonic crystal structure of the blue phase liquid crystal is equivalent to the wavelength of light, so it can selectively reflect light through Bragg reflection. In addition, the photonic band gap of the blue phase liquid crystal of the present application is narrow, and its color rendering is high.

[0062] In a second aspect, the present application provides a method for preparing a blue phase liquid crystal polymer fiber that changes color in mechanical response, comprising:

[0063] S1, dissolving the raw materials of the blue phase liquid crystal layer in a solvent to prepare a solution, heating the solution to completely volatilize the solvent in the solution, and raising the temperature to a clearing point of the blue phase liquid crystal to obtain a polymer liquid crystal prepolymer solution;

[0064] Specifically, the solvent includes at least one of ethanol, acetone, dichloromethane and dimethylformamide. The prepared solution is heated to 40-60°C to volatilize the solvent; after the solvent is completely volatilized, the temperature is raised to 85-90°C, which is the clearing point of the blue phase liquid crystal of the present application, to obtain a polymer liquid crystal prepolymer solution.

[0065] S2, passing the polymer fiber monofilament through the polymer liquid crystal prepolymer solution to obtain a precursor fiber; heating the precursor fiber to make the polymer liquid crystal prepolymer solution reach an isotropic state, and then quickly cooling the temperature of the precursor fiber to room temperature;

[0066] In the present application, the polymer fiber monofilament is a polyurethane fiber monofilament, and its surface is polished before use so that its surface has a certain degree of roughness, which serves as the inner core.

[0067] In the present application, the precursor fiber is heated to a temperature above the clearing point, preferably 100-105°C, so that the polymer liquid crystal prepolymer liquid reaches an isotropic state; then the temperature is cooled to the clearing point temperature of the polymer liquid crystal prepolymer liquid, i.e. 85-90°C; and then the temperature is rapidly cooled to room temperature at a cooling rate of 50-500°C / min, so that a layer of polymerizable blue phase liquid crystal with good lattice structure and large plates can be formed on the surface of the polyurethane fiber monofilament.

[0068] S3, the precursor fiber after cooling is polymerized by ultraviolet light to obtain a blue phase liquid crystal polymer fiber with mechanical response color change.

[0069] The precursor fiber is exposed to ultraviolet light with an energy density of 0.3 to 25 mw / cm 2 The blue phase liquid crystal polymer fiber with elastic skin-core fiber structure is obtained by irradiating the fiber with ultraviolet light for 0.1 to 0.5 hours for photopolymerization, so that the polymerizable blue phase liquid crystal on the surface of the polyurethane fiber monofilament in the precursor fiber is photopolymerized to obtain a blue phase liquid crystal polymer fiber with an elastic skin-core fiber structure, which has a mechanical response color change function.

[0070] The preparation process of the present application is simple and flexible, and a blue phase structure with good lattice structure and large plates can be obtained by rapid cooling. The prepared blue phase liquid crystal polymer fiber has good processability and high performance.

[0071] The blue phase liquid crystal polymer fiber of the present application changes color when an external force is applied, and has a controllable, stable and reversible force-responsive color change behavior. It has a narrow reflection bandgap and high color rendering index, and can be used in sensors, displays, stealth or anti-counterfeiting and other fields.

[0072] The present application is further described below by way of examples.

[0073] In the embodiment of the present application, the nematic liquid crystal is C6M, the chiral compound is a mixture of the non-polymerizable chiral compound R5011 and the polymerizable chiral compound DK756; the chain extender is 4-(6-(acryloyloxy)hexyloxy)benzoic acid; the crosslinker is EDDET; the photoinitiator is benzoin diethyl ether; and the aggregation inhibitor is p-methoxyphenol. All of the above raw materials can be purchased.

[0074] Example 1

[0075] This embodiment provides a method for preparing a blue phase liquid crystal polymer fiber that changes color in mechanical response, comprising:

[0076] Weigh the liquid crystal raw materials and mix them in the following ratio:

[0077]

[0078] S1, take the above raw materials and put them into a 3ml sample box, use a rubber dropper to draw 2-3 drops of dichloromethane and drip them into the sample box, stir thoroughly until the raw materials are completely dissolved by the solvent and mixed evenly. Place the mixed solution in a 60℃ oven for 0.5h until the dichloromethane solvent is completely volatilized, and raise the temperature to the clear point of the blue phase liquid crystal to obtain the polymer liquid crystal prepolymer solution.

[0079] S2, passing the polyurethane fiber monofilament through a polymer liquid crystal prepolymer liquid by a coaxial coating method, raising the temperature of the oven to 105° C. to make the polymer liquid crystal prepolymer liquid on the surface of the polyurethane fiber monofilament reach an isotropic state, and then cooling the temperature from the blue phase liquid crystal clearing point temperature to 26° C. at a cooling rate of 200° C. / min to form a blue phase polymerizable liquid crystal layer on the surface of the polyurethane fiber monofilament to obtain a precursor fiber;

[0080] S3, photopolymerizing the precursor fiber under ultraviolet light environment to polymerize the blue phase polymerizable liquid crystal layer to generate a blue phase liquid crystal layer, wherein the intensity of the ultraviolet light is 0.3mw / cm 2 The irradiation time is 30 minutes. After photopolymerization, an elastic core-skin fiber structure is formed, namely, a blue phase liquid crystal polymer fiber with mechanical response color change.

[0081] Example 2

[0082] This embodiment provides a method for preparing a blue phase liquid crystal polymer fiber that changes color in mechanical response, comprising:

[0083] Weigh the liquid crystal raw materials and mix them in the following ratio:

[0084]

[0085] S1, take the above raw materials and put them into a 3ml sample box, use a rubber dropper to draw 2-3 drops of dichloromethane and drop them into the sample box, stir thoroughly until the raw materials are completely dissolved by the solvent and mixed evenly. Place the mixed solution in a 60℃ oven for 0.3h until the dichloromethane solvent is completely volatilized, and raise the temperature to the clear point of the blue phase liquid crystal to obtain the polymer liquid crystal prepolymer solution.

[0086] S2, passing the polyurethane fiber monofilament through a polymer liquid crystal prepolymer liquid by a coaxial coating method, raising the temperature of the oven to 105° C. to make the polymer liquid crystal prepolymer liquid on the surface of the polyurethane fiber monofilament reach an isotropic state, and then cooling the temperature from the blue phase liquid crystal clearing point temperature to 26° C. at a cooling rate of 200° C. / min to form a blue phase polymerizable liquid crystal layer on the surface of the polyurethane fiber monofilament to obtain a precursor fiber;

[0087] S3, photopolymerizing the precursor fiber under ultraviolet light environment to polymerize the blue phase polymerizable liquid crystal layer to generate a blue phase liquid crystal layer, wherein the intensity of the ultraviolet light is 0.3mw / cm 2 The irradiation time is 30 minutes. After photopolymerization, an elastic core-skin fiber structure is formed, namely, a blue phase liquid crystal polymer fiber with mechanical response color change.

[0088] Example 3

[0089] This embodiment provides a method for preparing a blue phase liquid crystal polymer fiber that changes color in mechanical response, comprising:

[0090] Weigh the liquid crystal raw materials and mix them in the following ratio:

[0091]

[0092] S1, take the above raw materials and put them into a 3ml sample box, use a rubber dropper to draw 2-3 drops of dichloromethane and drop them into the sample box, stir thoroughly until the raw materials are completely dissolved by the solvent and mixed evenly. Place the mixed solution in a 60℃ oven for 0.3h until the dichloromethane solvent is completely volatilized, and raise the temperature to the clear point of the blue phase liquid crystal to obtain the polymer liquid crystal prepolymer solution.

[0093] S2, passing the polyurethane fiber monofilament through a polymer liquid crystal prepolymer liquid by a coaxial coating method, raising the temperature of the oven to 105° C. to make the polymer liquid crystal prepolymer liquid on the surface of the polyurethane fiber monofilament reach an isotropic state, and then cooling the temperature from the blue phase liquid crystal clearing point temperature to 26° C. at a cooling rate of 200° C. / min to form a blue phase polymerizable liquid crystal layer on the surface of the polyurethane fiber monofilament to obtain a precursor fiber;

[0094] S3, photopolymerizing the precursor fiber under ultraviolet light environment to polymerize the blue phase polymerizable liquid crystal layer to generate a blue phase liquid crystal layer, wherein the intensity of the ultraviolet light is 0.3mw / cm 2 The irradiation time is 30 minutes. After photopolymerization, an elastic core-skin fiber structure is formed, namely, a blue phase liquid crystal polymer fiber with mechanical response color change.

[0095] Comparative Example 1

[0096] The liquid crystal raw material of Comparative Example 1 does not contain a chain extender. The liquid crystal raw material ratio is:

[0097]

[0098] The preparation method of Comparative Example 1 is the same as that of Example 1.

[0099] Comparative Example 2

[0100] The liquid crystal raw material ratio of comparative example 2 is the same as that of embodiment 1. The difference between the preparation method of comparative example 2 and the preparation method of embodiment 1 is that the cooling rate from the clearing point temperature of the blue phase liquid crystal to room temperature is 0.5°C / min, which is the same as that of embodiment 1.

[0101] The blue phase liquid crystal polymer fiber prepared in Example 1 has a physical image, a polarizing microscope image and a reflection spectrum image of the blue phase liquid crystal after rapid cooling as shown in FIG. Figure 1 The left, middle and right pictures show the mechanical response color change effect of the color-changing blue phase liquid crystal fiber. Figure 2 shown.

[0102] from Figure 1 It can be seen from the actual picture and the polarizing microscope composition diagram that the Michael addition reaction of C6M and 4-(6-(acryloyloxy)hexyloxy)benzoic acid in the blue phase liquid crystal system can obtain blue phase liquid crystal with large plates, complete and stable lattice under rapid cooling; from the reflection spectrum diagram, it can be seen that the reflection bandwidth of the blue phase liquid crystal is narrow and the color rendering is good.

[0103] from Figure 2 It can be seen that the blue phase liquid crystal fibers prepared by this system change color due to the change in the lattice constant of the blue phase liquid crystal when external force is applied, which leads to a change in the reflection wavelength. It has the color change behavior in response to the increase of stress from red.

[0104] The blue phase liquid crystal polymer fiber prepared in Comparative Example 1 has a physical image, a polarizing microscope image and a reflection spectrum image of the blue phase liquid crystal after rapid cooling as shown in FIG. Figure 3 The left, middle and right figures are shown in the figure; the mechanical response color change effect diagram of the color-changing blue phase liquid crystal fiber is shown in Figure 4 shown.

[0105] from Figure 3 It can be seen that the blue phase liquid crystal prepared in the benzoic acid-free system in Comparative Example 1 exhibits an uneven and complete blue phase lattice structure under rapid cooling conditions due to the lack of the Michael addition reaction between C6M and 4-(6-(acryloyloxy)hexyloxy)benzoic acid, and the color rendering of the blue phase liquid crystal is poor. Furthermore, it can be seen from the reflection spectrum that the blue phase liquid crystal prepared in this system has low reflectivity and poor color rendering.

[0106] from Figure 4 It can be seen that in the blue phase liquid crystal fiber prepared in the benzoic acid-free system in Comparative Example 1, as the stress increases, the lattice constant of the blue phase liquid crystal changes, resulting in a change in the reflection wavelength and discoloration, and it has a mechanical response color change behavior.

[0107] The blue phase liquid crystal polymer fiber prepared in Comparative Example 2 has a real-life image of the blue phase liquid crystal after slowing down, a polarizing microscope image, and a reflection spectrum image as shown in FIG. Figure 5 As shown, the actual picture of the color-changing blue phase liquid crystal fiber is as follows Figure 6 shown.

[0108] from Figure 5 It can be seen that the blue phase liquid crystal prepared in Comparative Example 2 has a strong light scattering ability and poor color rendering due to slow cooling, and the lattice structure of the blue phase liquid crystal is incomplete.

[0109] from Figure 6 It can be seen that, in the blue phase liquid crystal fiber prepared by slow cooling in comparative example 2, as the stress increases, the lattice constant of the blue phase liquid crystal changes, which leads to a change in the reflection wavelength and a color change mechanical response color change behavior.

[0110] From the above test results, it can be seen that the blue phase liquid crystal of the present application has a blue phase structure with good lattice structure and large plates, a narrow photonic band gap and high color rendering; the prepared blue phase liquid crystal polymer fiber has good processability and high performance, and has very good application potential in the fields of sensors, displays, stealth and anti-counterfeiting.

[0111] Although the present application has been described in detail in general terms and in specific embodiments in this specification, it is obvious to those skilled in the art that some modifications or improvements may be made to the present application. Therefore, these modifications or improvements made without departing from the spirit of the present application are within the scope of protection claimed in the present application.

Claims

1. A blue phase liquid crystal polymer fiber with mechanical response color change, characterized in that: It is a skin-core structure, the skin layer is a blue phase liquid crystal layer, and the core layer is a polymer fiber monofilament; the blue phase liquid crystal polymer fiber can respond to color change under stress changes.

2. The blue phase liquid crystal polymer fiber according to claim 1, characterized in that: The blue phase liquid crystal layer includes the following raw materials in percentage by mass: Nematic liquid crystal 65-80%, chiral compound 3.5-5%, chain extender 5-15%, cross-linking agent 10-20%, photoinitiator 1-5% and inhibitor 0.1-1.5%; The chiral compounds include non-polymerizable chiral compounds and polymerizable chiral compounds; The polymer fibers include polyurethane fibers.

3. The blue phase liquid crystal polymer fiber according to claim 2, characterized in that: The nematic liquid crystal includes at least one of C6M, RM23, RM82, RM257, C4M or C3M; The non-polymerizable chiral compound is at least one of R5011, S5011, R811, S811, R1011, S1011, R3011, S3011 or CB15; the polymerizable chiral compound is DK756; The chain extender is benzoic acid or its derivatives; The cross-linking agent includes any one of EDDET, PETMP, HDT or SH-PEG2-SH; The photoinitiator includes at least one of benzoin dimethyl ether, benzoin diethyl ether, PI1173, PI184, TPO, PBZ or PI819; The polymerization inhibitor is p-methoxyphenol.

4. A method for preparing a blue phase liquid crystal polymer fiber with mechanical response color change, characterized in that: include: S1, dissolving the raw materials of the blue phase liquid crystal layer in a solvent to prepare a solution, heating the solution to completely volatilize the solvent in the solution, and raising the temperature to a clearing point of the blue phase liquid crystal to obtain a polymer liquid crystal prepolymer solution; S2, passing the polymer fiber monofilament through the polymer liquid crystal prepolymer solution to obtain a precursor fiber; heating the precursor fiber to make the polymer liquid crystal prepolymer solution reach an isotropic state, and then quickly cooling the temperature of the precursor fiber to room temperature; S3, the precursor fiber after cooling is polymerized by ultraviolet light to obtain a blue phase liquid crystal polymer fiber with mechanical response color change.

5. The preparation method according to claim 4, characterized in that: The solvent includes at least one of ethanol, acetone, dichloromethane and dimethylformamide; and the polymer fiber monofilament is a polyurethane fiber monofilament.

6. The preparation method according to claim 4, characterized in that: In S1, the heating temperature is 40 to 60°C.

7. The preparation method according to claim 4, characterized in that: The clearing point of the blue phase liquid crystal is 85-90°C.

8. The preparation method according to claim 4, characterized in that: The cooling rate in S2 is 50-500°C / min.

9. The preparation method according to claim 4, characterized in that: The ultraviolet light energy density of the ultraviolet light polymerization is 0.3 to 25 mw / cm 2 , the polymerization time is 0.1~0.5h.

10. Application of the mechanically responsive color-changing blue phase liquid crystal polymer fiber according to any one of claims 1 to 3 or the mechanically responsive color-changing blue phase liquid crystal polymer fiber prepared by the preparation method according to any one of claims 4 to 9 in the fields of sensors, displays, stealth or anti-counterfeiting.

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