Liquid crystal vitrimer, method for manufacturing same, material including same, and applications thereof

Abstract

The present disclosure provides a liquid vitrimer, a method for manufacturing same, a material including same, and applications thereof, the vitrimer being formed by polymerizing: a diacrylate-terminated reactive mesogen; a dithiol-terminated dynamic chain extender including thiourethane groups; a dithiol-terminated chain extender; a tetrathiol-terminated crosslinking agent; and a catalyst.

Description

Liquid crystal vitremer, method of manufacturing the same, material including the same, and application of the same

[0001] The embodiments of the present disclosure relate to a liquid crystal vitremer, a method for manufacturing the same, and a composite material formed therefrom; more specifically, they relate to a liquid crystal vitremer having properties of physical adjustment, self-healing, and reprocessing characteristics, a method for manufacturing the same, and a composite material formed therefrom.

[0002] Liquid Crystal Elastomers (LCEs) are stimulus-sensitive materials capable of reversible shape changes in response to external stimuli, possessing both the elasticity of rubber and the anisotropy of liquid crystals. Based on low-density polymer networks containing liquid crystal molecules, these LCEs enable reversible driving of large strokes and allow for the realization of sophisticated shape deformation designs beyond simple one-dimensional movements through the adjustment of local molecular arrangements in response to stimuli. Due to these characteristics, LCEs have high potential for application in various fields, such as artificial muscles, soft robots, and wearable devices.

[0003] To realize the shape deformation characteristics of LCEs, the design of the initial molecular arrangement plays a crucial role. To this end, methods involving the application of various physical or chemical processes prior to crosslinking are commonly used. Representative methods include physical tensile deformation, optical patterning techniques, and the application of electric or magnetic fields, through which the molecular arrangement can be fixed in a desired direction.

[0004] One method for redesigning the fixed shape deformation of such LCEs is Dynamic Covalent Chemistry. Dynamic Covalent Chemistry is a concept that allows chemical bonds to be activated under specific conditions to form new bonds, thereby enabling redesign and reprocessing.

[0005] However, existing dynamic covalent bonds have disadvantages, such as activation at relatively high temperatures, high cost, and difficulty in controlling operating temperature, thermomechanical properties, and optical properties.

[0006] The embodiments of the present disclosure aim to solve various problems, including those mentioned above, by applying a thiourethane dynamic covalent bond that can be rapidly activated at low temperatures and utilizes inexpensive commercial monomers, thereby providing a liquid crystal vitremer capable of controlling thermomechanical and optical properties while possessing self-healing and reprocessing characteristics, a method for manufacturing the same, and a composite material formed therefrom. However, these objectives are exemplary and the scope of the present disclosure is not limited by them.

[0007] According to one aspect of the present disclosure, a liquid crystal vitreamer formed by polymerizing a reactive liquid crystal monomer comprising a diacrylate terminal group; a dynamic chain extender comprising a dithiol terminal group and a thiourethane group; a chain extender comprising a dithiol terminal group; a crosslinking agent comprising a tetrathiol terminal group; and a catalyst is provided.

[0008] According to another perspective, a reactive liquid crystal monomer (reactive mesogen) containing a diacrylate terminal group; and

[0009] Step (S201) of producing a first mixture by mixing a dynamic chain extender including a dithiol terminal group and a thiourethane group and

[0010] Chain extender containing a dithiol terminal group;

[0011] A crosslinking agent containing a tetrarathiol terminal group; and

[0012] A method for manufacturing a liquid crystal vitreamer is provided, comprising a step (S202) of producing a second mixture mixed with a catalyst.

[0013] According to another perspective, a composite material formed from the liquid crystal vitremer is provided.

[0014] Other aspects, features, and advantages other than those described above will become clear from the following specific details, claims, and drawings for implementing the invention.

[0015] According to the exemplary embodiment of the present disclosure as described above, it is possible to realize a liquid crystal vitremer having self-healing and reprocessing properties while allowing control of thermomechanical and optical properties, a method for manufacturing the same, and a composite material formed therefrom. Of course, the scope of the present disclosure is not limited by these effects.

[0016] FIG. 1 illustrates the structure of a liquid crystal bitrimer according to an exemplary embodiment of the present disclosure.

[0017] FIG. 2 illustrates a dynamic exchange reaction and hydrogen bonding within a liquid crystal vitrimer according to an exemplary embodiment of the present disclosure.

[0018] FIG. 3 illustrates the structure of a compound used in the manufacturing process of a liquid crystal vitrimer according to an exemplary embodiment of the present disclosure.

[0019] FIG. 4 is a schematic diagram illustrating a method for manufacturing a dynamic chain extender according to an exemplary embodiment of the present disclosure.

[0020] FIG. 5 is a schematic diagram illustrating a method for manufacturing a liquid crystal vitrimer according to an exemplary embodiment of the present disclosure.

[0021] FIG. 6 is a figure showing the measured nematic-isotropic transition temperature for a liquid crystal vitrimer according to an exemplary embodiment of the present disclosure.

[0022] FIG. 7 is a figure showing the driving temperature of a liquid crystal bitrimer according to an exemplary embodiment of the present disclosure.

[0023] FIG. 8 is a figure showing the relative difference in transmitted light brightness according to the rotation angle between polarizers for a liquid crystal vitremer according to an exemplary embodiment of the present disclosure.

[0024] FIG. 9 is a figure showing the transmitted light brightness relative to stress for a liquid crystal vitremer according to an exemplary embodiment of the present disclosure.

[0025] FIG. 10 is a figure for measuring stress relief for a liquid crystal vitremer according to an exemplary embodiment of the present disclosure.

[0026] FIGS. 11 to 13 are figures showing the results of evaluating the reprocessing characteristics of a liquid crystal vitremer according to an exemplary embodiment of the present disclosure.

[0027] FIGS. 14 and 15 are figures showing the results of evaluating the molecular configuration programming characteristics of a liquid crystal vitremer according to an exemplary embodiment of the present disclosure.

[0028] The present disclosure is capable of various modifications and may have various embodiments; specific embodiments are illustrated in the drawings and described in detail in the detailed description. The effects and features of the present disclosure and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various forms.

[0029] In the following embodiments, terms such as first, second, etc. are used not in a limiting sense, but for the purpose of distinguishing one component from another component.

[0030] In the following examples, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0031] In the following embodiments, terms such as "include" or "have" mean that the features or components described in the specification are present, and do not preclude the possibility that one or more other features or components may be added.

[0032] In the following embodiments, when a part such as a layer, region, or component is described as being on or above another part, it includes not only cases where it is directly on top of another part, but also cases where another region, component, etc. is interposed in between.

[0033] In the drawings, the size of components may be exaggerated or reduced for convenience of explanation. For example, the size and thickness of each component shown in the drawings are depicted arbitrarily for convenience of explanation, and therefore the present disclosure is not necessarily limited to what is depicted.

[0034] Where an embodiment can be implemented differently, a specific sequence of operations may be performed differently from the order described. For example, two steps described consecutively may be performed substantially simultaneously or proceed in the reverse order of the description.

[0035] In this specification, "A and / or B" indicates the case where it is A, B, or both A and B. And, "at least one of A and B indicates the case where it is A, B, or both A and B."

[0036] In the following embodiments, when layers, regions, components, etc. are described as being connected, this includes cases where the layers, regions, components are directly connected, or / or cases where other layers, regions, components are interposed between the layers, regions, components to form an indirect connection. For example, when layers, regions, components, etc. are described as being electrically connected in this specification, it indicates cases where the layers, regions, components, etc. are directly electrically connected, and / or cases where other layers, regions, components, etc. are interposed between them to form an indirect electrical connection.

[0037] The x-axis, y-axis, and z-axis are not limited to the three axes of an orthogonal coordinate system but can be interpreted in a broader sense that includes them. For example, the x-axis, y-axis, and z-axis may be orthogonal to each other, but they may also refer to different directions that are not orthogonal to each other.

[0038] The advantages and features of the present disclosure and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure is complete and to fully inform those skilled in the art of the scope of the present disclosure, and the present disclosure is defined only by the scope of the claims.

[0039] The terms used in this disclosure are for describing the embodiments and are not intended to limit this disclosure. In this disclosure, the singular form may include the plural form unless specifically stated otherwise in the text. The terms “comprises” and / or “comprising” used in this disclosure do not exclude the presence or addition of one or more other components in addition to the components mentioned. Throughout the disclosure, the same reference numerals refer to the same components, and “and / or” may include each of the mentioned components and all combinations of one or more. Although terms such as “first,” “second,” etc., are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another. Accordingly, the first component mentioned below may be the second component within the technical scope of this disclosure.

[0040] The word "exemplary" is used in this disclosure to mean "used as an example or illustration." Any embodiment described as "exemplary" in this disclosure should not be interpreted as being preferred or having an advantage over other embodiments.

[0041] Spatially relative terms such as "below," "beneath," "lower," "above," and "upper" may be used to facilitate the description of the relationship between one component and other components as illustrated in the drawings. Spatially relative terms should be understood as encompassing different orientations of components during use or operation, in addition to the orientations depicted in the drawings. For example, if a component depicted in a drawing is inverted, a component described as "below" or "beneath" of another component may be placed "above" of that component. Therefore, the exemplary term "below" may encompass both the lower and upper directions. Components may also be oriented in other directions, and accordingly, spatially relative terms may be interpreted according to the orientation.

[0042] Unless otherwise defined, all terms used in this disclosure (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which this disclosure pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0043] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings. When describing with reference to the drawings, identical or corresponding components are given the same reference numerals, and redundant descriptions thereof will be omitted.

[0044] A liquid crystal bitrimer according to one aspect of the present invention will be described in detail below.

[0045] The above liquid crystal vitrimer is a reactive liquid crystal monomer (reactive mesogen) containing a diacrylate terminal group;

[0046] Dynamic chain extender comprising dithiol terminal groups and thiourethane groups;

[0047] Chain extender containing a dithiol terminal group;

[0048] It can be formed by polymerizing a crosslinking agent containing a tetrathiol terminal group; and a catalyst.

[0049] The thiourethane group in this specification It refers to the group represented by . (* and *' are bonding sites with neighboring atoms.)

[0050] A liquid crystal vitremer according to one embodiment of the present invention is formed as described above, thereby having self-healing and reprocessing characteristics through thiourethane dynamic covalent bonds and hydrogen bonds, while also having control characteristics for thermomechanical and optical properties.

[0051] According to one embodiment, the dynamic chain extender may be represented by the following Formula 1 or Formula 2:

[0052] <Equation 1>

[0053]

[0054] <Equation 2>

[0055]

[0056] Among the above Equation 1,

[0057] X 11 , X 12 , X 13 and X 14 are independently alkylene groups, and

[0058] Among the above Equation 2,

[0059] X 21 and X 22 They are independently alkylene groups.

[0060] The alkylene groups in this specification may independently be methylene, ethylene, propylene, butylene, pentylene, hexalene, heptylene, octylene, nonylene, or decanene groups, and these may be substituted.

[0061] According to one embodiment, the X in Formula 1 above 11 It can be a hexaren group.

[0062] According to one embodiment, the X in Formula 1 above 12 It can be an ethylene group.

[0063] According to one embodiment, the X in Formula 1 above 13 It can be an ethylene group.

[0064] According to one embodiment, the X in Formula 1 above 14 It can be an ethylene group.

[0065] According to one embodiment, the dynamic chain extender can be represented by the following formula A.

[0066] <Equation A>

[0067]

[0068] According to one embodiment, the reactive liquid crystal monomer is 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82), 1,4-bis-[4-(3-acryloyloxypropyloxy)benzoyloxy]-2-methylbenzene (1,4-bis-[4-(3-acryloyloxypropyloxy)benzoyloxy]-2-methylbenzene (RM257), 4-[6-(acryloyloxy)hexyloxy]phenyl 4-[6-(acryloyloxy)hexyloxy]benzoate (4-[6-(Acryloyloxy)hexyloxy]phenyl4-[6-(acryloyloxy)hexyloxy]benzoate) and thereof It can be selected from any combination.

[0069] According to one embodiment, the chain extender may be represented by the following Formula 3 or Formula 4:

[0070] <Equation 3>

[0071]

[0072] <Equation 4>

[0073]

[0074] Among the above Equation 3,

[0075] X 32 , X 33 , X 34 They are independently alkylene groups, and

[0076] Among the above Equation 4,

[0077] X 42 It can be an alkylene group.

[0078] According to one embodiment, the above X 31 is X 11 It can be the same as.

[0079] According to one embodiment, the above X 32 is X 12 It can be the same as.

[0080] According to one embodiment, the above X 33 is X 13 It can be the same as.

[0081] According to one embodiment, the above X 31 It can be a hexaren group.

[0082] According to one embodiment, the above X 42 is X 22 It can be the same as.

[0083] According to one embodiment, the chain extender can be represented by the following formula B:

[0084] <Equation B>

[0085]

[0086] According to one embodiment, the crosslinking agent can be represented by the following Formula 5.

[0087] <Equation 5>

[0088]

[0089] Among the above Equation 5,

[0090] X 51 , X 52 , X 53 and X 54 They are independently alkylene groups.

[0091] According to one embodiment, X 51 , X 52 , X 53 and X 54 It can be an ethylene group.

[0092] According to one embodiment, the crosslinking agent can be represented by the following formula C.

[0093] <Equation C>

[0094]

[0095] According to one embodiment, the catalyst may be a basic catalyst.

[0096] According to one embodiment, the catalyst may be an amine-based catalyst. For example, it may be dipropylamine, but is not limited thereto.

[0097] According to one embodiment, the ratio of the molar amount of the liquid crystal monomer to the total molar amount of the dynamic chain extender, chain extender, and crosslinking agent may be about 1:1 to 1:1.5, about 1:1.05 to 1.2, or about 1:1.05 to 1:1.15.

[0098] According to one embodiment, the molar ratio of the liquid crystal monomer and the crosslinking agent may be about 1:0.01 to 1:0.5 or about 1:0.01 to 1:0.3.

[0099] According to one embodiment, the crosslinking agent may be about 0.01 to 0.5 wt% or about 0.01 to 0.3 wt% with respect to the total mass of the liquid crystal monomer and the dynamic chain extender.

[0100] According to one embodiment, the catalyst may be about 1 to 5 wt% or about 1 to 3 wt% with respect to the total mass of the liquid crystal monomer and the dynamic chain extender.

[0101] According to another aspect, a composite material formed from the liquid crystal bitrimer is provided.

[0102] According to one embodiment, the composite material may be characterized by reprocessability and / or self-healing.

[0103] According to one embodiment, the composite material may have a super coil-shaped structure.

[0104] According to one embodiment, the composite material may further include liquid metal or carbon nanotubes.

[0105] According to one embodiment, the composite material may be a material for artificial muscles, soft robots, or wearable devices, but is not limited thereto.

[0106] Up to this point, only liquid crystal vitremers and composite materials formed therefrom have been described, but the present disclosure is not limited thereto. For example, a method for manufacturing such liquid crystal vitremers is also considered to fall within the scope of the present disclosure.

[0107] According to one embodiment, a method for manufacturing the liquid crystal vitreamer comprises: a reactive liquid crystal monomer (reactive mesogen) including a diacrylate terminal group; and

[0108] Step (S201) of producing a first mixture by mixing a dynamic chain extender including a dithiol terminal group and a thiourethane group and

[0109] Chain extender containing a dithiol terminal group;

[0110] A crosslinking agent containing a tetrarathiol terminal group; and

[0111] It may include a step (S202) of producing a second mixture by mixing the catalyst.

[0112] By following the above manufacturing method, the compositional ratio between the dynamic chain extender and the chain extender can be adjusted, thereby allowing for the control of the operating temperature, optical and thermomechanical properties.

[0113] According to one embodiment, the method may further include a step (S203) of producing a third mixture by mixing the first mixture and the second mixture.

[0114] According to one embodiment, the method may further include a casting step (S204) of the third mixture.

[0115] According to one embodiment, a heating step (S205) of the third mixture may be further included after the molding step.

[0116] According to one embodiment, the heating step may be performed at a temperature of about 100°C or higher and 150°C or lower.

[0117] According to one embodiment, the heating step may be performed for about 5 minutes or more and 15 hours or less.

[0118] According to one embodiment, the thiol-Michael addition reaction step in the third compound may be included.

[0119] The reactive liquid crystal monomer, dynamic chain extender, chain extender, crosslinking agent, and catalyst in this specification may be interpreted independently of each other with reference to the previously described.

[0120] According to another aspect, the dynamic chain extender and a method for manufacturing the same are provided.

[0121] The description of dynamic chain extenders can be interpreted by referring to the previously explained information.

[0122] According to one embodiment, the method for manufacturing the dynamic chain extender comprises: a mixing step (S101) of a first monomer including a dithiol terminal group and a metal catalyst; and

[0123] It may include a dropwise addition step (S103) of a first monomer containing a diisocyanate terminal group.

[0124] According to one embodiment, the first monomer may be represented by the following Equation 6 or Equation 7:

[0125] <Equation 6>

[0126]

[0127] <Equation 7>

[0128]

[0129] Among the above Equation 6,

[0130] X 12 , X 13 and X 14 are independently alkylene groups, and

[0131] Among the above Equation 7,

[0132] X22 It can be an alkyene group.

[0133] According to one embodiment, among the above Equation 6, X 12 , X 13 and X 14 It can be an ethylene group.

[0134] According to one embodiment, the second monomer can be represented by the following Equation 8:

[0135] <Equation 8>

[0136]

[0137] Among the above Equation 8,

[0138] X 11 It can be an alkyene group.

[0139] According to one embodiment, among the above Equation 8, X 11 It can be a hexaren group.

[0140] According to one embodiment, a first stirring step (S102) may be further included after the mixing step.

[0141] According to one embodiment, the first stirring step may be performed at a speed of about 100 rpm to 500 rpm.

[0142] According to one embodiment, the first stirring step can be performed at a temperature of about 30°C or higher and 70°C or lower.

[0143] According to one embodiment, a second stirring step (S104) may be further included after the drop step.

[0144] According to one embodiment, the second stirring step can be performed at a speed of about 300 rpm to 1000 rpm.

[0145] According to one embodiment, the second stirring step may be performed at a temperature of about 40°C or higher and 70°C or about 50°C or higher and 60°C or lower.

[0146] According to one embodiment, the molar ratio of the first monomer and the second monomer may be about 3:1 to 1:1 or about 2:1.

[0147] According to one embodiment, the metal catalyst may be about 1 to 5 wt% or about 1 to 3 wt% with respect to the total mass of the first monomer and the second monomer.

[0148] Hereinafter, a liquid crystal vitremer according to one embodiment of the present invention, a method for manufacturing the same, and a composite material formed therefrom will be described in more detail with reference to synthesis examples and embodiments.

[0149] Synthetic example

[0150] Experiment preparation

[0151] 2,2'-(ethylenedioxy)diethanethiol (EDDT) having two or more thiol groups (-SH), hexamethylene diisocyanate (HDI) having two or more isocyanate groups (-NCO), pentaerythritol tetra(mercaptopropionate) (PETMP) having four or more thiol groups, zinc(II) dibutyldithiocarbamate (Zn(DTC)2), and dipropylamine (DPA) were purchased from Sigma-Aldrich, and the reactive liquid crystal monomer 11,4-bis[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82) was purchased from Synthon Chemical and used. The structures of the above compounds are shown in Fig. 3.

[0152] Synthesis Example: Synthesis of Dynamic Chain Extender

[0153]

[0154] 4.5 mL of EDDT was added to 20.146 g of Zn(DTC), and the mixture was stirred at a speed of 100 to 200 rpm at a temperature of 50°C. While stirring, 2.2 mL of HDI was slowly added drop by drop so that the reaction ratio of HDI to EDDT was 1:2. After adding all of the HDI, the mixture was stirred vigorously for 5 seconds, and then stirred at a speed of 500 rpm at a temperature of 50°C for 1 hour to prepare 7.5 g of dynamic chain extender EDDT-TU. The above preparation method is briefly illustrated in Fig. 4.

[0155] Preparation Example 1: Preparation of Liquid Crystal Vitremer TU_25

[0156]

[0157] A first mixture is produced by mixing RM82, a reactive liquid crystal monomer, and EDDT-TU, a dynamic chain extender prepared according to Synthesis Example 1; a second mixture is produced by mixing EDDT, a chain extender, and PETMP, a crosslinking agent; and a third mixture is produced by mixing the first mixture and the second mixture. Here, the molar ratios of RM82, EDDT-TU, EDDT, and PETMP are 49.77%, 11.41%, 34.28%, and 4.56%, respectively, and the third mixture further contains 2 wt% of catalyst DPA based on the total weight of RM82, EDDT-TU, EDDT, and PETMP.

[0158] After washing, a microscope glass slide (75 mm x 25 mm) was coated with Rain-X, a glass water repellent. To control the thickness of the liquid crystal vitremer, 0.3 mm thick spacers were placed at both ends of the glass slide. After the mixture was transferred to the prepared glass slide, it was covered with another glass slide. The prepared cell was heated at a temperature of 120°C for 12 hours to promote oligomerization and crosslinking through a thiol-Michael addition reaction, thereby producing the liquid crystal vitremer TU_2 of Example 2. The above preparation method is briefly illustrated in Fig. 5.

[0159] Preparation Examples 2 to 5

[0160] Liquid crystal vitremers TU_0, TU_50, TU_75, and TU_100 of Examples 1 and 3 to 5 were prepared in the same manner as Preparation Example 1, except that the molar ratios of RM82, EDDT-TU, EDDT, and PETMP in Preparation Example 1 were modified as shown in Table 1 below.

[0161] That is, the liquid crystal vitremers according to Preparation Examples 1 to 5 were synthesized with an excess amount of Thiol relative to Acrylate of 10 mol% to induce a linked exchange reaction, fixed the amounts of RM82 and PETMP, and adjusted the ratio of dynamic chain extender EDDT-TU and chain extender EDDET to 0:100 / 25:75 / 50:50 / 75:25 / 100:0 to produce the liquid crystal vitremers as shown below.

[0162] Examples Liquid Crystal Trimer Acrylate terminated monomer Thiol terminated monomer RM82 (mol%) TU (mol%) EDDET (mol%) PETMP (mol%) Example 1 TU_0 49.77 0 45.66 4.56 Example 2 TU_25 49.77 11.41 34.28 4.56 Example 3 TU_50 49.77 22.8 322.8 34.56 Example 4 TU_75 49.77 34.28 11.41 4.56 Example 5 TU_100 49.77 45.66 04.56

[0163] [Evaluation Example 1: T according to the composition of the dynamic chain extender ni [and driving temperature control](evaluation method)

[0164] Nematic-isotropic transition temperature (T) of liquid crystal vitrimer according to the composition of dynamic chain extender ni To verify the nematic-isotropic transition temperature for Examples 1 to 5, the change in heat quantity with temperature was measured using a differential scanning calorimeter (DSC) and the temperature of the inflection point was measured, and the results are shown in Fig. 6.

[0165] After 100% uniaxial stretching of the liquid crystal vitremers of Examples 1 to 5 and fixing them at room temperature, T ni When heated, thermal driving occurs as it contracts along the aligned direction and expands in a direction perpendicular to it, and the results are shown in Fig. 7. At this time, the driving strain can be controlled by the tensile strain applied initially.

[0166] (Evaluation Results)

[0167] FIG. 6 illustrates the change in heat quantity according to temperature for Examples 1 to 5. Liquid crystal vitremers change to an isotropic state above a certain temperature as the arrangement of the nematic state changes randomly; this temperature is called the nematic-isotropic transition temperature (T ni It is called ). At this time, the liquid crystal elastomer is T ni At the above temperatures, the orientation changes, and accordingly, actuation behavior may be exhibited. Through Figure 6, it can be confirmed that the nematic-isotropic transition temperature decreases as the composition of the dynamic chain extender increases.

[0168] Through Figure 7, it can be confirmed that the higher the composition of the dynamic chain extender, the lower the driving temperature.

[0169] In a polymer network containing liquid crystal monomers, the liquid crystal monomers are connected by chain extenders. As the length of these chain extenders increases, the liquid crystal monomers can gain mobility with less energy and form disordered orientations, which allows for a phase transition to occur at a low temperature. Therefore, Figures 6 and 7 demonstrate that the glass transition temperature and driving temperature of the liquid crystal vitremer can be controlled by adjusting the composition of the dynamic chain extender.

[0170] [Evaluation Example 2: Control of Optical Properties According to Composition of Dynamic Chain Extender]

[0171] (Evaluation Method)

[0172] To compare optical properties according to the composition of dynamic chain extenders, the relative difference in transmitted light brightness according to the rotation angle between polarizers was determined for Examples 1 to 5, and the results are shown in Fig. 8. For the liquid crystal vitremers of each example, samples in the polydomain state were 100% uniaxially stretched and stored for 12 hours, after which optical properties resulting from double refraction were measured using a polarizing optical microscope.

[0173] For Examples 1 to 5, the brightness of transmitted light according to stress was confirmed, and the results are shown in FIG. 9.

[0174] (Evaluation Results)

[0175] FIG. 8 is a polar coordinate graph showing the relative difference in brightness of transmitted light according to the rotation angle between polarizers for Examples 1 to 5, and it can be confirmed that the higher the composition of the dynamic chain extender, the greater the relative difference in brightness of transmitted light, and the better the liquid crystal is aligned.

[0176] FIG. 9 is a graph showing the brightness of transmitted light relative to stress for Examples 1 to 5, and it can be seen that under the same tensile conditions, the brightness of transmitted light increases as the composition of the dynamic chain extender increases.

[0177] In other words, it can be confirmed that the higher the composition ratio of the dynamic chain extender, the better the alignment, and the liquid crystals are rapidly aligned even at low uniaxial strain. This can be attributed to hydrogen bonding between the thiourethane groups of the dynamic chain extender, and thus, as shown in Figures 8 and 9, it is demonstrated that the optical properties of the liquid crystal vitremer can be controlled by adjusting the composition of the dynamic chain extender.

[0178] [Evaluation Example 3: Control of Mechanical Properties According to Composition of Dynamic Chain Extender]

[0179] (Evaluation Method)

[0180] Stress relaxation for Examples 1 to 5 was measured and is shown in FIG. 10.

[0181] (Evaluation Results)

[0182] Through Figure 10, it can be seen that the higher the composition ratio of the dynamic chain extender, the shorter the stress relaxation time due to the dynamic exchange reaction of the liquid crystal vitremer.

[0183] [Evaluation Example 4: Low-temperature driving, reprocessing, and self-healing characteristics of liquid crystal vitremers]

[0184] (Evaluation Method)

[0185] For Example 5, which is 20 mm long, stress was applied to uniaxially stretch it to a length of about 50 mm, and then it was placed in water at 45°C to evaluate low-temperature driving characteristics, and the results are shown in Fig. 11.

[0186] After cutting Examples 1 and 5, reprocessing characteristics were evaluated by reprocessing using a hot press under high temperature and high pressure conditions of 150°C and 10 MPa, and the results are shown in Fig. 12.

[0187] After applying a scratch to Example 5, a reprocessing characteristic evaluation was performed under high temperature conditions of 150°C for 30 minutes, and the results are shown in FIG. 13.

[0188] (Evaluation Results)

[0189] Through Fig. 11, it can be seen that the liquid crystal vitremer containing a dynamic chain extender is reprocessed to a size similar to its original size of 23 mm after being placed in water at 45°C.

[0190] Through FIG. 12, it can be seen that Example 1, which does not contain a dynamic chain extender, is not reprocessed by heat and shows a non-uniform shape, whereas Example 5, which contains a dynamic chain extender, is reprocessed into the same film shape.

[0191] Through Fig. 13, it can be confirmed that the liquid crystal vitremer containing a dynamic chain extender is reprocessed under high temperature conditions of 150°C for 30 minutes.

[0192] [Evaluation Example 5: Molecular Orientation Programming of Liquid Crystal Vitreamers]

[0193] (Evaluation Method)

[0194] For Example 5, programming into a specific shape was performed under conditions of 150°C and 30 minutes, and after shape deformation by tension, a temperature above the nematic-isotropic transition temperature was applied to confirm the change, and the results are shown in FIG. 14.

[0195] For Example 5, programming was performed under IR conditions and verified, and the results are shown in FIG. 15.

[0196] (Evaluation Results)

[0197] Through FIG. 14, it can be confirmed that Example 5, which includes a dynamic chain extender, can be programmed with a specific molecular orientation, thereby enabling secondary and tertiary iterative reprocessing and reshaping, as well as reprocessing back to the original state. Additionally, through FIG. 15, it can be confirmed that programming is also possible under IR conditions.

[0198] In conclusion, the present invention provides a liquid crystal vitreamer utilizing thiourethane dynamic covalent bonds and hydrogen bonds that can be rapidly activated at relatively low temperatures and utilize inexpensive commercial monomers, and a method for manufacturing the same. More specifically, the present invention provides a liquid crystal vitreamer capable of dynamic exchange reaction through a Michael addition reaction utilizing a base catalyst and a one-pot method based on acrylate-thiol click chemistry, by mixing a dynamic chain extender containing two or more thiol terminal groups and a thiourethane group with a conventional chain extender having two or more thiol terminal groups.

[0199] Furthermore, as can be seen from the preceding evaluation examples, the nematic-isotropic transition temperature, operating temperature, optical properties, and thermomechanical properties of the liquid crystal vitremer can be controlled by adjusting the composition of the dynamic chain extender containing thiourethane groups. Additionally, it possesses reprocessing and self-healing properties, and allows for repetitive molecular orientation programming.

[0200] Therefore, it can be seen that the liquid crystal vitremer is suitable for use as a composite material because it can be controlled with optimized operating temperature, optical and mechanical properties, and also possesses reprocessing and self-healing properties.

[0201] Although preferred embodiments according to the present invention have been described above with reference to the drawings and embodiments, this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the scope of protection of the present invention should be determined by the appended claims.

[0202] Although the present disclosure has been described with reference to the embodiments illustrated in the drawings, this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true scope of technical protection of the present disclosure should be determined by the technical spirit of the appended claims.

Claims

1. Reactive liquid crystal monomer (reactive mesogen) containing a diacrylate terminal group; Dynamic chain extender comprising dithiol terminal groups and thiourethane groups; Chain extender containing a dithiol terminal group; Crosslinking agent containing tetrathiol terminal groups; and are formed by polymerizing a catalyst, wherein the reactive liquid crystal monomer is 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82), 1,4-bis-[4-(3-acryloyloxypropyloxy)benzoyloxy]-2-methylbenzene (RM257), 4-[6-(acryloyloxy)hexyloxy]phenyl 4-[6-(acryloyloxy)hexyloxy]benzoate and any combination thereof selected liquid crystal vitremer.

2. In Paragraph 1, The above dynamic chain extender is a liquid crystal vitremer represented by the following Formula 1 or Formula 2: <Equation 1> <Equation 2> Among the above Equation 1, X 11 , X 12 , X 13 and X 14 are independently alkylenes, and Among the above Equation 2, X 21 and X 22 They are independently alkynes.

3. In Paragraph 2, Among the above Equation 1, The above X 11 is a hexylene group, and The above X 12 is an ethylene group, and The above X 13 is an ethylene group, and The above X 14 is a liquid crystal vitrimer that is an ethylene group.

4. In Paragraph 1, The above chain extender is a liquid crystal vitremer represented by the following Formula 3 or Formula 4: <Equation 3> <Equation 4> Among the above Equation 3, X 32 , X 33 , X 34 They are independently alkylene groups, and Among the above Equation 4, X 42 It is an alkylene group.

5. In Paragraph 1, The above crosslinking agent is a liquid crystal vitremer represented by the following formula 5: <Equation 5> Among the above Equation 5, X 51 , X 52 , X 53 and X 54 They are independently alkylene groups.

6. In Paragraph 1, The above catalyst is a liquid crystal vitrimer that is a basic catalyst.

7. An artificial muscle comprising the liquid crystal vitremer of claim 1.

8. An actuator comprising the liquid crystal vitremer of claim 1.

9. A reactive liquid crystal monomer (reactive mesogen) containing a diacrylate terminal group; and Step (S201) of producing a first mixture by mixing a dynamic chain extender including a dithiol terminal group and a thiourethane group and Chain extender containing a dithiol terminal group; A crosslinking agent containing a tetrarathiol terminal group; and It includes a step (S202) of producing a second mixture by mixing the catalyst, and The above reactive liquid crystal monomer is selected from 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82), 1,4-bis-[4-(3-acryloyloxypropyloxy)benzoyloxy]-2-methylbenzene (1,4-bis-[4-(3-acryloyloxypropyloxy)benzoyloxy]-2-methylbenzene (RM257), 4-[6-(acryloyloxy)hexyloxy]phenyl 4-[6-(acryloyloxy)hexyloxy]benzoate (4-[6-(Acryloyloxy)hexyloxy]phenyl4-[6-(acryloyloxy)hexyloxy]benzoate) and any combination thereof, Method for manufacturing liquid crystal vitrimer.

10. In Paragraph 9, A method for manufacturing a liquid crystal vitreamer, further comprising a step (S203) of producing a third mixture by mixing the first mixture and the second mixture.

11. In Paragraph 10, A method for manufacturing a liquid crystal vitremer, further comprising a casting step (S204) of the above third mixture.

12. In Paragraph 11, A method for manufacturing a liquid crystal vitreamer, further comprising a heating step (S205) of the third mixture after the molding step.

Images