阅读说明：本技术 一种可螺旋弯曲的液晶弹性体纤维及其制备方法与应用 (Spirally bendable liquid crystal elastomer fiber and preparation method and application thereof ) 是由 袁冬 白龙飞 游雨欣 张悦 赵威 周国富 于 2021-08-24 设计创作，主要内容包括：本发明属于液晶材料技术领域,公开了一种可螺旋弯曲的液晶弹性体纤维及其制备方法与应用。该液晶弹性体纤维的制备方法,包括以下步骤：(1)将液晶单体、硫醇、迈克尔加成反应催化剂和光引发剂分散在挥发性有机溶剂中进行反应,持续搅拌至所述挥发性有机溶剂挥发完全,制得液晶弹性体预聚物；(2)将所述液晶弹性体预聚物牵拉成丝,经加捻后进行固定,使用紫外光照射进行聚合,得到所述液晶弹性体纤维。所述液晶弹性体纤维可实现三维螺旋卷曲,克服了现有液晶弹性体材料伸缩变形单一的缺陷,并具有变形范围更大、遇热形变且可逆回复的特点。(The invention belongs to the technical field of liquid crystal materials, and discloses a spirally bendable liquid crystal elastomer fiber, and a preparation method and application thereof. The preparation method of the liquid crystal elastomer fiber comprises the following steps: (1) dispersing a liquid crystal monomer, mercaptan, a Michael addition reaction catalyst and a photoinitiator in a volatile organic solvent for reaction, and continuously stirring until the volatile organic solvent is completely volatilized to prepare a liquid crystal elastomer prepolymer; (2) and drawing the liquid crystal elastomer prepolymer into filaments, twisting, fixing, and polymerizing by using ultraviolet irradiation to obtain the liquid crystal elastomer fiber. The liquid crystal elastomer fiber can realize three-dimensional spiral curling, overcomes the defect of single stretching deformation of the existing liquid crystal elastomer material, and has the characteristics of larger deformation range, thermal deformation and reversible recovery.)

1. The preparation method of the liquid crystal elastomer fiber is characterized by comprising the following steps of:

(1) dispersing a liquid crystal monomer, mercaptan, a Michael addition reaction catalyst and a photoinitiator in a volatile organic solvent for reaction, and continuously stirring until the volatile organic solvent is completely volatilized to prepare a liquid crystal elastomer prepolymer;

(2) and drawing the liquid crystal elastomer prepolymer into filaments, twisting, fixing, and polymerizing by using ultraviolet irradiation to obtain the liquid crystal elastomer fiber.

2. The method of claim 1, wherein the photoinitiator in step (1) comprises at least one of benzoin dimethyl ether, phenyl bis (2,4, 6-trimethylbenzoyl) phosphine oxide, and 2-hydroxy-4- (2-hydroxyethoxy) -2-methyl propiophenone.

3. The method according to claim 1, wherein the liquid crystal monomer in step (1) comprises at least one of liquid crystal monomer HCM009, liquid crystal monomer HCM008, liquid crystal monomer HCM020 and liquid crystal monomer HCM 021.

4. The method according to claim 1, wherein the mercaptan in step (1) comprises at least two of pentaerythritol tetrakis-3-mercaptopropionate, 2' - (1, 2-ethanediylbiooxo) bisethanethiol, 1, 6-hexanedithiol, and methyl mercaptan.

5. The method according to claim 1, wherein the Michael addition reaction catalyst in step (1) comprises at least one of triethylamine, dipropylamine, and n-butylamine.

6. The method according to claim 1, wherein the components for preparing the liquid crystal elastomer prepolymer in the step (1) are as follows in parts by mass: 72.5 to 81.5 portions of liquid crystal monomer, 17.0 to 26.4 portions of mercaptan, 0.6 to 1.2 portions of Michael addition reaction catalyst and 0.05 to 0.3 portion of photoinitiator.

7. The production method according to claim 1, wherein the polymerization is performed in step (2) under a closed nitrogen atmosphere using ultraviolet light irradiation.

8. The production method according to claim 1, wherein the ultraviolet light irradiation in the step (2) has an irradiation intensity of 95 to 110mW/cm²(ii) a The time of ultraviolet irradiation in the step (2) is 5-10 min.

9. A liquid crystal elastomer fiber produced by the production method according to any one of claims 1 to 8.

10. Use of a liquid crystalline elastomeric fiber according to claim 9 in the field of clothing.

Technical Field

The invention belongs to the technical field of liquid crystal materials, and particularly relates to a spirally bendable liquid crystal elastomer fiber, and a preparation method and application thereof.

Background

The liquid crystal elastomer is a novel high polymer material, is obtained by properly crosslinking a liquid crystal phase sequence (self-organization) and an elastic high molecular weight, can generate shape change by changing the arrangement of mesomorphic elements under the stimulation of an external field (an electric field, temperature, light and the like), further shows the change of shape, soft elasticity and optical characteristics, is a very active field in the research of the current high polymer material, and has good application prospect in various aspects such as artificial muscle, nano machinery, artificial intelligence and the like.

However, the conventional liquid crystal elastomer material has low shrinkage and limited deformation degree, and the application of the liquid crystal elastomer material in more fields is limited. Therefore, the present invention is intended to provide a novel liquid crystal elastomer fiber having a larger deformation range and reversible deformation.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art described above. Therefore, the invention provides a spirally bendable liquid crystal elastomer fiber, and a preparation method and application thereof. The liquid crystal elastomer fiber can realize three-dimensional spiral curling, overcomes the defect of single stretching deformation of the existing liquid crystal elastomer material, and has the characteristics of larger deformation range, thermal deformation and reversible recovery.

The invention provides a preparation method of a liquid crystal elastomer fiber, which comprises the following steps:

(1) dispersing a liquid crystal monomer, mercaptan, a Michael addition reaction catalyst and a photoinitiator in a volatile organic solvent for reaction, and continuously stirring until the volatile organic solvent is completely volatilized to prepare a liquid crystal elastomer prepolymer;

(2) and drawing the liquid crystal elastomer prepolymer into filaments, twisting, fixing, and polymerizing by using ultraviolet irradiation to obtain the liquid crystal elastomer fiber.

In the Michael addition reaction of mercaptan and a liquid crystal monomer, the liquid crystal monomer containing acrylate end group can flexibly adjust the crosslinking density and the polymer structure through the click reaction of mercaptan-acrylate in the Michael addition of the mercaptan and an alpha, beta-unsaturated carbonyl compound, and the thioether structure is generated by polymerization. The liquid crystal elastomer fiber prepared by the method has stronger bulkiness, and the cohesive force and the dimensional stability during fiber processing are improved.

The invention relates to a method for preparing liquid crystal elastomer fiber, which comprises the steps of pre-twisting (twisting, wherein one end of the fiber is fixed, the other end of the fiber rotates, the process is called twisting, the twisting is a process of twisting by utilizing bending and rotating motion of the fiber so as to fix the longitudinal relation between the fibers, the bending can cause winding, the twisting can form a twist, and tension and twisting are necessary conditions for twisting) and then crosslinking polymerization operation is carried out, so that the liquid crystal elastomer fiber generates three-dimensional twisting orientation, and a three-dimensional spiral curled fiber structure can be formed when being subjected to thermal stimulation; by controlling the number of turns of the twisting rotation, the degree of the helical deformation of the fibers can be controlled. Through rotary twisting, the deformation range of the prepared liquid crystal elastomer fiber is greatly improved, and the fiber performance is obviously improved. The liquid crystal elastomer fiber prepared by the invention can cause the disorder of the arrangement direction of partial liquid crystal elements under the thermal stimulation, so as to cause the phase transformation from a liquid crystal phase to an isotropic phase, and the change of molecular orientation can further cause the whole liquid crystal elastomer fiber to generate the macroscopic deformation of a three-dimensional spiral curled structure; when the liquid crystal elastomer fiber is subjected to and removed from thermal stimulation, spontaneous three-dimensional spiral crimp deformation and reversible recovery can be realized for avoiding the interaction of self space, and the deformation amplitude is larger than that of the traditional liquid crystal elastomer fiber.

Preferably, the photoinitiator in step (1) comprises at least one of benzoin dimethyl ether, phenyl bis (2,4, 6-trimethylbenzoyl) phosphine oxide, and 2-hydroxy-4- (2-hydroxyethoxy) -2-methyl propiophenone.

Preferably, the liquid crystal monomer in step (1) includes at least one of liquid crystal monomer HCM009, liquid crystal monomer HCM008, liquid crystal monomer HCM020, and liquid crystal monomer HCM 021. The liquid crystal monomers all contain acrylate end groups, and besides the same acrylate groups, the cross-linking density and the polymerization degree of a liquid crystal elastomer system are affected differently by factors such as different flexible chain lengths and different other end group groups in the liquid crystal monomers. The liquid crystal elastomer fiber prepared by the Michael addition reaction disturbs the arrangement direction of partial liquid crystal structures under the thermal stimulation, causes the phase transformation from a liquid crystal phase to an isotropic phase, and the change of molecular orientation further causes the whole liquid crystal elastomer fiber to generate the macroscopic deformation of a three-dimensional spiral curled structure.

Preferably, the mercaptan in step (1) comprises at least two of pentaerythritol tetra-3-mercaptopropionate, 2' - (1, 2-ethanediylbiooxo) bisethanethiol, 1, 6-hexanedithiol and methyl mercaptan.

Preferably, the michael addition reaction catalyst in the step (1) comprises at least one of triethylamine, dipropylamine and n-butylamine.

Preferably, the volatile organic solvent in step (1) comprises at least one of dichloromethane, toluene, xylene and tetrahydrofuran.

Preferably, the components for preparing the liquid crystal elastomer prepolymer in the step (1) are as follows in parts by mass: 72.5 to 81.5 portions of liquid crystal monomer, 17.0 to 26.4 portions of mercaptan, 0.6 to 1.2 portions of Michael addition reaction catalyst and 0.05 to 0.3 portion of photoinitiator. The invention realizes the control of the polymerization degree and the viscosity of the prepolymer of the liquid crystal elastomer by adjusting the dosage proportion of the mercaptan and the Michael addition reaction catalyst; the elastic strength of the liquid crystal elastomer prepolymer can be adjusted by adjusting the ratio of the liquid crystal monomer to the mercaptan, so that the fiber can be conveniently processed and prepared.

Preferably, step (1) is carried out by carrying out the reaction under yellow light conditions.

Preferably, the polymerization is performed using ultraviolet light irradiation in step (2) under a closed nitrogen atmosphere.

Preferably, the intensity of the ultraviolet light irradiation in the step (2) is 95-110mW/cm²。

Preferably, the time of the ultraviolet irradiation in the step (2) is 5-10 min.

The invention also provides a liquid crystal elastomer fiber prepared by the preparation method.

The invention also provides application of the liquid crystal elastomer fiber in the field of clothing. The invention discovers that when the liquid crystal elastomer fiber is used as a part of weaving material in clothes and is woven together with other normal textile fibers, the spiral bending structure of the liquid crystal elastomer fiber can contract when the temperature of the prepared fabric rises, so that the upper and lower layers of normal textile fibers adjacent to each other are driven to elongate, the pores are enlarged, the effect of enhancing the air permeability is achieved, and good cooling feeling is realized. When the temperature is reduced, the liquid crystal elastomer fiber is restored to the original shape, so that the pores are reduced to reduce the dissipation of human body heat, and the heat preservation effect is achieved.

Compared with the prior art, the invention has the following beneficial effects:

the invention makes the three-dimensional spiral geometric structure of the liquid crystal elastomer recorded through the stretching and twisting operation, so that the prepared liquid crystal elastomer fiber can generate the deformation of three-dimensional spiral curling when being heated and stimulated (has thermal responsiveness), and meanwhile, the deformation degree of the fiber can be controlled through the twisting degree. Through the operation, the deformation range of the prepared liquid crystal elastomer fiber is greatly improved, and the fiber performance is obviously improved. Due to this property, the liquid crystal elastomer fiber can be used to prepare a self-regulating breathable fabric having a temperature response. Compared with the conventional liquid crystal elastomer fiber which can only stretch and contract along the axial direction to generate reversible deformation when being subjected to and removed from thermal stimulation, the liquid crystal elastomer fiber prepared by the invention can realize three-dimensional spiral crimp deformation and reversible recovery when being subjected to and removed from the thermal stimulation. The invention also controls the polymerization degree and viscosity of the prepolymer of the liquid crystal elastomer by adjusting the dosage proportion of the mercaptan and the Michael addition reaction catalyst.

Drawings

FIG. 1 is a schematic view of a liquid crystal elastomer prepolymer in an example of the present invention after being drawn into filaments and twisted, and then fixed;

FIG. 2 is a photograph showing the thermal response of the liquid crystal elastomer fiber according to the embodiment of the present invention after being spirally curled and recovered after leaving the heat source;

FIG. 3 is a diagram showing the deformation of a conventional liquid crystal elastomer material and a thermally responsive liquid crystal elastomer fiber produced according to an embodiment of the present invention; wherein a is a photograph of the deformation degree of the traditional liquid crystal elastomer material under the condition of tensile force or thermal stimulation, and b is a simulation diagram of three-dimensional spiral curling deformation and recovery of the thermal response liquid crystal elastomer fiber in the embodiment of the invention;

FIG. 4 is a graph illustrating the effect of self-regulating the air permeability of a knitted fabric according to the present invention according to the ambient temperature.

Detailed Description

In order to make the technical solutions of the present invention more apparent to those skilled in the art, the following examples are given for illustration. It should be noted that the following examples are only preferred embodiments of the present invention, and the claimed protection scope is not limited thereto, and any modification, substitution, combination made without departing from the spirit and principle of the present invention are included in the protection scope of the present invention.

The starting materials, reagents or apparatuses used in the following examples are conventionally commercially available or can be obtained by conventionally known methods, unless otherwise specified.

According to the thermal response type liquid crystal elastomer fiber provided by the embodiment of the invention, the preparation method comprises the following steps:

(1) adding liquid crystal monomers HCM008 and HCM009 and a photoinitiator IR819 into a sample bottle, adding a stirrer, dropwise adding a proper amount of dichloromethane for dissolving, stirring until the system is transparent, and dropwise adding 2, 2' - (1, 2-ethanediylbis oxo) bisethanethiol, pentaerythritol tetra-3-mercaptopropionate and dipropylamine; the raw materials used in the method comprise the following components in parts by weight: 72.5-81.5 parts of liquid crystal monomers (HCM008 and HCM009), 17.0-26.4 parts of mercaptan (2, 2' - (1, 2-ethanediylbiooxo) bisethanethiol, pentaerythritol tetra-3-mercaptopropionate), 0.6-1.2 parts of catalyst (dipropylamine) and 0.05-0.3 part of photoinitiator (IR 819); continuously stirring at room temperature under yellow light to perform Michael addition reaction until dichloromethane serving as a solvent is completely volatilized to form a viscous liquid crystal elastomer prepolymer;

(2) a proper amount of the liquid crystal elastomer prepolymer was dipped with a spatula and slowly drawn into a filament, and after the helical twisting, the resulting fiber was fixed on a device as shown in FIG. 1. Then placing the device in a closed nitrogen atmosphere to perform ultraviolet irradiation to induce polymerization, wherein the irradiation intensity of the ultraviolet irradiation is 95-110mW/cm²And irradiating the fiber for 5-10min to obtain the thermal response type liquid crystal elastomer fiber.

The liquid crystal monomer HCM008 can be purchased from Jiangsu Hecheng New Material Co., Ltd, and has a structural formula:

HCM009 is available from Jiangsu and New materials, Inc. and has the structural formula:

photoinitiator IR819 is available from Tianjin Xiencsi Biotechnology Ltd and has the structural formula:

2, 2' - (1, 2-ethanediylbis-oxo) bisethanethiol is available from Merck, Germany and has the formula:

pentaerythritol tetra-3-mercaptopropionate, available from Aladdin, having the formula

Fig. 2 shows a schematic diagram of the thermo-responsive liquid crystal elastomer fiber prepared in this example, and it can be seen that when the temperature of the thermo-responsive liquid crystal elastomer fiber is raised to T' (above Tg), liquid crystal molecules change from an ordered state to a disordered state, and when the elastomer fiber is stimulated, the elastomer fiber avoids three-dimensional spiral curling and winding caused by self-space interaction, so as to form a tendril-like curled structure; when the temperature is reduced to T (room temperature, below Tg), the liquid crystal molecules reversibly change back to the original monodomain ordered state, and the responsive liquid crystal elastomer fiber returns to its original state. In fig. 3, a is a photograph of the deformation degree of the conventional liquid crystal elastomer material under the stimulation of tensile force or heat, and the deformation shrinkage rate is only about 40%; and b in fig. 3 is a simulation diagram of the deformation and recovery of the three-dimensional spiral crimp of the thermally responsive liquid crystal elastomer fiber in the present embodiment, the degree of crimp depends on the geometry of the twisted three-dimensional spiral, and the value H1/H2 can be controlled within 2-5, i.e. the larger the ratio is, the larger the degree of spiral crimp is. Therefore, the response type liquid crystal elastomer fiber prepared by the embodiment of the invention can not only break through the conventional traditional shrinkage rate, but also realize large-amplitude three-dimensional spiral crimp deformation when being stimulated.

The preparation method of the self-adjusting breathable knitted fabric with temperature response by using normal textile fibers and the thermal response type liquid crystal elastomer fibers (spiral crimped fibers) as knitting materials and adopting a weft knitting mode comprises the following steps:

first, yarns are formed into a fabric in a loop shape along the width direction of the fabric, each yarn is fed at about ninety degrees (weft direction) to the fabric forming direction (warp direction), and the schematic diagram of the fabric obtained by weaving is shown in the left diagram in fig. 4, wherein white fibers are thermal response type liquid crystal elastomer fibers (spiral crimp fibers) prepared by the embodiment of the invention, gray black fibers are conventional textile fibers, and the two fibers are interlaced with each other.

As shown in fig. 4, the self-regulating air-permeable knitted fabric obtained by compositely knitting the normal textile fiber and the thermal responsive liquid crystal elastomer fiber has a temperature response characteristic. When the knitted fabric is heated, the thermal response type liquid crystal elastomer fiber is spirally curled and shrunk, so that the upper layer and the lower layer of the adjacent normal textile fiber are driven to be elongated, the pores are enlarged, the effect of enhancing air permeability is achieved, and good cooling feeling is realized. When the knitted fabric is cooled, the liquid crystal elastomer fiber is restored to the original shape, so that the pores are reduced, and a better heat preservation effect is achieved.

The embodiments of the present application have been described in detail with reference to the drawings, but the present application is not limited to the embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present application. Furthermore, the embodiments and features of the embodiments of the present application may be combined with each other without conflict.