Liquid crystal vitrimer, method for manufacturing same, material including same, and applications thereof
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-03-06
- Publication Date
- 2026-08-13
Smart Images
Figure KR2026003668_13082026_PF_FP_ABST
Abstract
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 liquid crystal vitremers, methods for manufacturing the same, materials comprising the same, and applications thereof; more specifically, to liquid crystal vitremers having stable thermal driveability, control of physical properties, self-healing and reprocessing characteristics, methods for manufacturing the same, materials comprising the same, and applications thereof.
[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, conventional dynamic covalent bonds have disadvantages such as activation at relatively high temperatures, low thermal actuation, high cost, and difficulty in controlling material properties including 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 allows for rapid activation of the exchange reaction at low temperatures and the use of inexpensive commercial monomers, thereby providing a liquid crystal vitremer capable of controlling physical properties such as thermomechanical and optical properties while possessing stable thermal actuation, 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 vitrimer formed by polymerizing a reactive liquid crystal monomer 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82); a dynamic chain extender represented by Formula 1 below; a crosslinking agent comprising a tetrathiol terminal group; and a catalyst is provided:
[0008] <Equation 1>
[0009]
[0010] Among the above Equation 1,
[0011] X 11 is an alkylene group, and
[0012] X 12 is a hectylene group.
[0013] According to another perspective, a composite material formed from the above liquid crystal vitremer is provided.
[0014] According to another perspective, the reactive liquid crystal monomer 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82); and
[0015] Step (S201) of producing a first mixture by mixing a dynamic chain extender represented by the above Equation 1 and
[0016] Chain extender containing a dithiol terminal group;
[0017] A crosslinking agent containing a tetrarathiol terminal group; and
[0018] A method for manufacturing a liquid crystal vitreamer is provided, comprising a step (S202) of producing a second mixture mixed with a catalyst.
[0019] Other aspects, features, and advantages other than those described above will become clear from the specific details, claims, and drawings for implementing the invention below.
[0020] 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.
[0021] FIG. 1 illustrates the structure of a liquid crystal vitreamer and hydrogen bonding within the liquid crystal vitreamer according to an exemplary embodiment of the present disclosure.
[0022] FIG. 2 is a schematic diagram illustrating a method for manufacturing a dynamic chain extender according to an exemplary embodiment of the present disclosure.
[0023] FIG. 3 is a schematic diagram illustrating a method for manufacturing a liquid crystal vitrimer according to an exemplary embodiment of the present disclosure.
[0024] FIG. 4 is a figure showing the hydrogen bond strength of a liquid crystal vitrimer according to an exemplary embodiment of the present disclosure.
[0025] FIG. 5 is a figure showing the gel fraction of a liquid crystal vitrimer according to an exemplary embodiment of the present disclosure.
[0026] 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.
[0027] FIG. 7 is a figure showing the melting temperature of a liquid crystal vitrimer according to an exemplary embodiment of the present disclosure.
[0028] FIG. 8 is a figure showing the results of WAXS (wide-angle X-ray scattering) for a liquid crystal bitrimer according to an exemplary embodiment of the present disclosure.
[0029] FIG. 9 is a figure showing the results of 2D WAXS (wide-angle X-ray scattering) for a liquid crystal bitrimer according to an exemplary embodiment of the present disclosure.
[0030] FIG. 10 is a figure showing the results of in-situ WAXS (wide-angle X-ray scattering) for a liquid crystal vitrimer according to an exemplary embodiment of the present disclosure.
[0031] FIG. 11 is a figure showing the results of dynamic mechanical analysis (DMA) for a liquid crystal vitremer according to an exemplary embodiment of the present disclosure.
[0032] FIGS. 12 and 13 are drawings showing the mechanical properties of a liquid crystal vitremer according to an exemplary embodiment of the present disclosure using a Universal Testing Machine (UTM).
[0033] FIG. 14 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.
[0034] FIG. 15 is a figure confirming the double refraction of an aligned liquid crystal vitremer film under a polarizing optical microscope for a liquid crystal vitremer according to an exemplary embodiment of the present disclosure.
[0035] FIG. 16 is a figure showing the thermal driving characteristics of a liquid crystal vitrimer according to an exemplary embodiment of the present disclosure.
[0036] FIGS. 17 and 18 are figures showing the results of evaluating the reprocessing characteristics of a liquid crystal vitremer according to an exemplary embodiment of the present disclosure.
[0037] FIG. 19 is a figure showing the results of evaluating the molecular configuration programming characteristics of a liquid crystal vitremer according to an exemplary embodiment of the present disclosure.
[0038] 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.
[0039] 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.
[0040] In the following examples, singular expressions include plural expressions unless the context clearly indicates otherwise.
[0041] 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.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] 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."
[0046] 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.
[0047] 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.
[0048] 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.
[0049] 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.
[0050] 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.
[0051] 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.
[0052] 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.
[0053] 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.
[0054] A liquid crystal bitrimer according to one aspect of the present invention will be described in detail below.
[0055] The above liquid crystal vitremer is a reactive liquid crystal monomer, 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82);
[0056] A dynamic chain extender represented by Formula 1 below;
[0057] Chain extender containing a dithiol terminal group;
[0058] It can be formed by polymerizing a crosslinking agent containing a tetrathiol terminal group; and a catalyst:
[0059] <Equation 1>
[0060]
[0061] Among the above Equation 1,
[0062] X 11 is an alkylene group, and
[0063] X 12 is a hectylene group.
[0064] The thiourethane group in this specification It refers to the group represented by . (* and *' are bonding sites with neighboring atoms.)
[0065] 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.
[0066] 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.
[0067] According to one embodiment, the above X 11It can be a hexylene group.
[0068] According to one embodiment, the dynamic chain extender can be represented by the following formula A.
[0069] <Equation A>
[0070]
[0071] According to one embodiment, the chain extender can be represented by the following Formula 2:
[0072] <Equation 2>
[0073]
[0074] Among the above Equation 2,
[0075] X 22 It can be an alkylene group.
[0076] According to one embodiment, the above X 22 is X 12 It can be the same as.
[0077] According to one embodiment, the above X 22 It can be a hexaren group.
[0078] According to one embodiment, the chain extender can be represented by the following formula B:
[0079] <Equation B>
[0080]
[0081] According to one embodiment, the crosslinking agent can be represented by the following Formula 3.
[0082] <Equation 3>
[0083]
[0084] Among the above Equation 3,
[0085] X 31 , X 32 , X 33 and X 34 They are independently alkylene groups.
[0086] According to one embodiment, X 31, X 32 , X 33 and X 34 It can be an ethylene group.
[0087] According to one embodiment, the crosslinking agent can be represented by the following formula C.
[0088] <Equation C>
[0089]
[0090] According to one embodiment, the catalyst may be a basic catalyst.
[0091] According to one embodiment, the catalyst may be an amine-based catalyst. For example, it may be n-butylamine, but is not limited thereto.
[0092] 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.
[0093] 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 1:0.3.
[0094] 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.
[0095] 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.
[0096] According to the implementation,
[0097] According to another aspect, a composite material formed from the liquid crystal bitrimer is provided.
[0098] According to one embodiment, the composite material may be characterized by reprocessability and / or self-healing.
[0099] According to one embodiment, the composite material may have a super coil-shaped structure.
[0100] According to one embodiment, the composite material may further include liquid metal or carbon nanotubes.
[0101] According to one embodiment, the composite material may be a material for artificial muscles, soft robots, or wearable devices, but is not limited thereto.
[0102] 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.
[0103] According to one embodiment, the method for manufacturing the liquid crystal vitreamer comprises a reactive liquid crystal monomer, 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene, RM82); and
[0104] A first mixture generation step (S201) in which a dynamic chain extender represented by the following formula 1 is mixed, and
[0105] Chain extender containing a dithiol terminal group;
[0106] A crosslinking agent containing a tetrarathiol terminal group; and
[0107] It may include a step (S202) of producing a second mixture mixed with a catalyst:
[0108] <Equation 1>
[0109]
[0110] Among the above Equation 1,
[0111] X 11is an alkylene group, and
[0112] X 12 is a hectylene group.
[0113] 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.
[0114] 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.
[0115] According to one embodiment, the casting step (S204) of the third mixture may be further included.
[0116] According to one embodiment, a heating step (S205) of the third mixture may be further included after the casting step.
[0117] According to one embodiment, the heating step may be performed at a temperature of about 100°C or higher and 150°C or lower.
[0118] According to one embodiment, the heating step may be performed for about 5 minutes or more and 15 hours or less.
[0119] According to one embodiment, the thiol-Michael addition reaction step in the third compound may be included.
[0120] 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.
[0121] According to another aspect, the dynamic chain extender and a method for manufacturing the same are provided.
[0122] The description of dynamic chain extenders can be interpreted by referring to the previously explained information.
[0123] According to one embodiment, the method for manufacturing the dynamic chain extender comprises: a mixing step (S101) of 1,6-hexanedithil and a metal catalyst; and
[0124] It may include a dropwise addition step (S103) of a first monomer containing a diisocyanate terminal group.
[0125] According to one embodiment, the first monomer can be represented by the following Equation 2:
[0126] <Equation 2>
[0127]
[0128] Among the above Equation 2,
[0129] X 11 It can be an alkyene group.
[0130] According to one embodiment, the above X 11 It can be a hexaren group.
[0131] According to one embodiment, the metal catalyst may be a zinc catalyst. For example, it may be zinc(II) dibutyldithiocarbamate (Zn(DTC)2), but is not limited thereto.
[0132] According to one embodiment, a first stirring step (S102) may be further included after the mixing step.
[0133] According to one embodiment, the first stirring step may be performed at a speed of about 100 rpm to 500 rpm.
[0134] 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.
[0135] According to one embodiment, a second stirring step (S104) may be further included after the drop step.
[0136] According to one embodiment, the second stirring step can be performed at a speed of about 300 rpm to 1000 rpm.
[0137] 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.
[0138] According to one embodiment, the molar ratio of the 1,6-hexanedithol and the first monomer may be about 1:1 to 3:1 or about 2:1.
[0139] 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 1,6-hexanedithol and the first monomer.
[0140] 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.
[0141] Synthetic example
[0142] Experiment preparation
[0143] 1,6-hexanedithiol (HDT) 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) dibutyl dithiocarbamate (Zn(DTC)2), and n-butylamine (nBA) 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.
[0144] Synthesis Example: Synthesis of Dynamic Chain Extender
[0145]
[0146] 8 g of dynamic chain extender HDT-TU was prepared by reacting 5.1 ml of HDI and 2.7 ml of HDT in a 2:1 molar ratio at 50°C for 1 hour in the presence of Zn(DTC)2. The above preparation method is briefly illustrated in Fig. 2.
[0147] Preparation Example 1: Preparation of Liquid Crystal Vitremer TU_25
[0148]
[0149] A first mixture is produced by mixing RM82, a reactive liquid crystal monomer, and HDT-TU, a dynamic chain extender prepared according to Synthesis Example 1; a second mixture is produced by mixing HDT, 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, HDT-TU, HDT, and PETMP are 1: 0.2: 0.8: 0.05, respectively, and the third mixture further contains 2 wt% of catalyst DPA based on the total weight of RM82, HDT-TU, HDT, and PETMP.
[0150] After cleaning, 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 via a thiol-Michael addition reaction, thereby producing the liquid crystal vitremer TU 0.2 of Example 2. The above preparation method is briefly illustrated in Fig. 3.
[0151] Preparation Examples 2 to 6
[0152] Except for modifying the molar ratios of RM82, HDT-TU, HDT, and PETMP in Preparation Example 1 as shown in Table 1 below, liquid crystal vitremers TU 0.0, TU 0.4, TU 0.6, TU 0.8, and TU 1.0 of Examples 1 and 3 to 6 were prepared in the same manner as Preparation Example 1.
[0153] That is, the liquid crystal vitremers according to Preparation Examples 1 to 6 were synthesized with an excess amount of Thiol relative to Acrylate of about 10 mol% to induce a linked exchange reaction, fixed the amounts of RM82 and PETMP, and adjusted the ratio of dynamic chain extender HDT-TU and chain extender HDT to 0:100 / 20:80 / 40:60 / 60:40 / 80:20 / 100:0 to produce the liquid crystal vitremers as shown below.
[0154] [Evaluation Example 1: Comparison of Hydrogen Bonding Strength According to Composition of Dynamic Chain Extender]
[0155] (Evaluation Method)
[0156] To compare the hydrogen bonding strength in liquid crystal vitremers according to the composition of dynamic chain extenders, FT-IR was used at a wavelength of 1640 cm⁻ 1 The hydrogen bonding peak formed by C=O in the band and 3300 cm⁻¹ -1 The hydrogen bond peak formed by the NH bond in the band was confirmed, and the results are shown in Figure 4.
[0157] (Evaluation Results)
[0158] Figure 4 is a figure showing the absorbance according to wavelength for Examples 1 to 6. Through Figure 4, it can be confirmed that the higher the composition of the dynamic chain extender, the greater the intensity of the hydrogen bond peak, that is, the greater the intensity of the hydrogen bond.
[0159] [Evaluation Example 2: Comparison of Gel Fraction According to Composition of Dynamic Chain Extender]
[0160] (Evaluation Method)
[0161] To compare the gel fraction in the liquid crystal vitremer according to the composition of the dynamic chain extender, a cross-linked thiourethane liquid crystal vitremer film was immersed in chloroform for 24 hours and then dried in a vacuum oven for 24 hours. The masses before and after immersion in chloroform were measured and compared, and the results are shown in Figure 5.
[0162] (Evaluation Results)
[0163] Figure 4 is a figure showing the absorbance according to wavelength for Examples 1 to 6. Through Figure 4, it can be confirmed that the higher the composition of the dynamic chain extender, the greater the intensity of the hydrogen bond peak, that is, the greater the intensity of the hydrogen bond.
[0164] Figure 5 illustrates the gel fractions for Examples 1 to 6. Through Figure 5, it can be seen that the gel fraction gradually increases as the composition of the dynamic chain extender increases. This can be attributed to the fact that physical crosslinking occurs due to hydrogen bonding of the thiourethane, causing the liquid crystal vitremer to form double crosslinks.
[0165] [Evaluation Example 3: Comparison of Thermal Properties According to Composition of Dynamic Chain Extender]
[0166] (Evaluation Method)
[0167] In order to confirm the thermal characteristics according to the composition of the dynamic chain extender, the change in heat quantity according to temperature was confirmed for Examples 1 to 5 using a differential scanning calorimeter (DSC), and the results are shown in Figures 6 and 7.
[0168] (Evaluation Results)
[0169] Figures 6 and 7 illustrate the change in heat quantity according to temperature for Examples 1 to 6.
[0170] Liquid crystal vitremers transition 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 can be exhibited. Through Fig. 6, the nematic-isotropic transition temperature can be confirmed, and it can be seen that the higher the composition of the dynamic chain extender, the lower the nematic-isotropic transition temperature. Therefore, it has the effect of enabling shape transformation at a relatively low temperature.
[0171] The liquid crystal vitremer of the present invention has a crystal structure formed in the liquid crystal vitremer network due to a chain extender, and the melting temperature (T) on the DSC is m ) was measured. Through Fig. 7, Example 1, which does not contain a dynamic chain extender, T at around 50°C m This appears, and as the composition of the dynamic chain extender increases, T at around 190℃ m It can be confirmed that this is found. Therefore, in this case, T ni Since the temperature is much lower than that, it maintains crystallinity, enabling stable thermal operation. Additionally, it can be confirmed that chain extenders and dynamic chain extenders can form different crystal structures.
[0172] [Evaluation Example 4: Comparison of Crystal Structures According to Composition of Dynamic Chain Extender]
[0173] (Evaluation Method)
[0174] In order to confirm the crystal structure according to the composition of the dynamic chain extender, WAXS (wide-angle X-ray scattering) measurements were performed on Examples 1 to 6, and the graph thereof is shown in Fig. 8, and the 2D WAXS pattern is shown in Fig. 9.
[0175] In addition, to confirm the change in the crystal structure of the liquid crystal vitremer as the temperature increases, in-situ WAXS measurements were performed on Examples 1 to 6, and the results are shown in FIG. 10.
[0176] (Evaluation Results)
[0177] Through Figures 8 and 9, it can be seen that the crystal structure present in the liquid crystal vitremer changes as the composition of the dynamic chain extender increases. In TU0.0 of Example 1, which does not contain a dynamic chain extender, four peaks were measured, and it can be seen that as the composition of the dynamic chain extender increases, the intensity of two peaks gradually increases and the remaining two peaks disappear. Through this, it can be seen that the composition of the dynamic chain extender affects the formation of the crystal structure of the liquid crystal vitremer.
[0178] Through Fig. 10, the change in the crystal structure of the liquid crystal vitremer as the temperature increased could be confirmed according to the composition of the dynamic chain extender. In Examples 1 to 3, where the composition of the dynamic chain extender is low, T m At temperatures above, the crystal structure disappears and only the amorphous peak remains, but in Examples 4 to 6, which have a high composition of dynamic chain extender, it can be confirmed that the crystal structure is maintained even at high temperatures.
[0179] [Evaluation Example 5: Comparison of Thermomechanical Properties According to Composition of Dynamic Chain Extender]
[0180] (Evaluation Method)
[0181] In order to confirm the thermomechanical properties according to the composition of the dynamic chain extender, dynamic mechanical analysis (DMA) was performed on Examples 1 to 6, and the results are shown in Fig. 11.
[0182] (Evaluation Results)
[0183] Through Fig. 11, it can be confirmed that liquid crystal vitremers with a high composition of dynamic chain extenders maintain a higher storage modulus because they have the effect of maintaining their crystal structure even at high temperatures.
[0184] [Evaluation Example 6: Comparison of Mechanical Properties According to Composition of Dynamic Chain Extender]
[0185] (Evaluation Method)
[0186] In order to confirm the mechanical properties according to the composition and crystallinity of the dynamic chain extender, the mechanical properties of Examples 1 to 6 were measured using a Universal Testing Machine (UTM), and the results are shown in FIG. 12, FIG. 13, Table 2, and Table 3.
[0187] (Evaluation Results)
[0188] In FIG. 12, FIG. 13, Table 2, and Table 3, C- represents a sample in which crystallization has been formed, and nC- represents a sample in which crystallization has not been formed. In all examples, it can be confirmed that the sample has higher mechanical properties when crystallization is formed compared to when crystallization is not formed.
[0189] [Evaluation Example 7: Control of Optical Properties According to Composition of Dynamic Chain Extender]
[0190] (Evaluation Method)
[0191] To compare optical properties according to the composition of dynamic chain extenders, the properties of liquid crystal molecules aligning in a specific direction were confirmed for Examples 1 to 6, and the results are shown in FIG. 14. For the liquid crystal vitremers of each example, samples in the polydomain state were stretched 100% uniaxially and stored for 12 hours, after which optical properties resulting from double refraction were measured using a polarizing optical microscope.
[0192] In addition, for Examples 1 and 6, the double refraction of the aligned liquid crystal vitremer films was confirmed under a polarizing optical microscope, and the results are shown in FIG. 15. (Scale bar = 1000 μm)
[0193] (Evaluation Results)
[0194] FIG. 14 is a polar coordinate graph showing the relative difference in transmitted light brightness according to the rotation angle between polarizers for Examples 1 to 6. It can be seen that as the composition of the dynamic chain extender increases, the bright optical characteristics decrease and the alignment of the liquid crystal is restricted, confirming that the composition of the dynamic chain extender affects the alignment performance of the liquid crystal. Additionally, through FIG. 15, the alignment of liquid crystal molecules can be confirmed more clearly.
[0195] [Evaluation Example 8: Control of Thermal Actuation Characteristics According to Composition of Dynamic Chain Extender]
[0196] (Evaluation Method)
[0197] After 100% uniaxial stretching the liquid crystal vitremers of Examples 1 to 6 and fixing them at room temperature, T ni When heated above, 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. 16. At this time, the driving strain can be controlled by the tensile strain applied initially.
[0198] (Evaluation Results)
[0199] Through Fig. 16, it can be seen that in the case of an example with a low composition of dynamic chain extender, a large driving deformation occurs with a normalized dimension perpendicular to the aligned direction of about 1.7 or more. As the composition of the dynamic chain extender increases, it can be confirmed that a driving deformation occurs with a normalized dimension perpendicular to the aligned direction of about 1.3 or more, even though the movement of the chains and the orientation of the liquid crystal are restricted because the crystal structure is maintained even at high temperatures.
[0200] [Evaluation Example 9: Reprocessing and Self-Healing Properties of Liquid Crystal Vitremers]
[0201] (Evaluation Method)
[0202] To compare the self-healing performance of liquid crystal vitremers using heat, the liquid crystal vitremers of Example 1 and Example 3 were cut and hot-pressed at 150°C at 10 MPa for 30 minutes, and the results are shown in FIG. 17.
[0203] For the liquid crystal vitremers before and after the above hot-press, i.e., the original film and the reprocessed film, toughness was measured using a UTM, and the results are shown in Fig. 18, and self-healing efficiency was measured and is shown in Table 4.
[0204] (Evaluation Results)
[0205] Through Fig. 17, it can be seen that the liquid crystal vitremer without a dynamic chain extender does not undergo reprocessing and is not formed into a film, whereas the film containing a dynamic chain extender undergoes a dynamic exchange reaction and is reprocessed and restored into a uniform film.
[0206] In addition, through Figure 18 and Table 4, the toughness and self-healing efficiency of the original film and the reprocessed film of Example 3 were checked, and it was confirmed that more than 80% of the toughness measured in the original film was recovered.
[0207] [Evaluation Example 10: Molecular Orientation Programming of Liquid Crystal Vitreamers]
[0208] (Evaluation Method)
[0209] For the liquid crystal vitremers of Examples 1 and 3, programming into a specific shape was performed under conditions of 150°C for 1 hour, and after removing the shape through shape deformation, the nematic-isotropic transition temperature (T ni Changes were observed by applying a temperature above ) and the results are shown in Fig. 19.
[0210] (Evaluation Results)
[0211] Through FIG. 19, the liquid crystal vitremer of Example 1, which does not contain a dynamic chain extender, after removing the shape, T ni Above, when heat is applied, it returns to its initial rectangular shape, but the liquid crystal vitremer of Example 3 containing a dynamic chain extender T after the shape is removed ni As described above, it can be confirmed that applying heat causes it to return to the programmed shape. In other words, it can be seen that it returns from the existing rectangular shape to the programmed twisted shape, and it can be confirmed that repetitive molecular orientation reprogramming is possible in various forms thereafter.
[0212] In conclusion, the present invention provides a liquid crystal vitremer utilizing thiourethane dynamic covalent bonds and hydrogen bonds that can be rapidly activated at relatively low temperatures and utilize inexpensive commercial monomers, as well as a method for manufacturing the same. Furthermore, the liquid crystal vitremer of the present invention can maintain crystallinity and possess stable thermal drive because its nematic-isotropic transition temperature is much lower than the melting temperature.
[0213] In addition, as can be seen from the previous evaluation examples, by controlling the composition of a dynamic chain extender containing a thiourethane group, the hydrogen bonding strength, gel fraction, thermal properties, crystal structure, thermomechanical properties, mechanical properties, and optical properties of the liquid crystal vitremer can be controlled. Furthermore, it has reprocessing and self-healing properties and allows for repetitive molecular orientation programming.
[0214] Therefore, it can be seen that the liquid crystal vitremer has stable thermal driving properties and can be controlled with optimized thermal properties, crystal structure, thermomechanical properties, mechanical properties, and optical properties, while also possessing reprocessing and self-healing properties, making it suitable for use in composite materials.
[0215] 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.
[0216] 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 technical scope of protection of the present disclosure should be determined by the technical spirit of the appended claims.
[0217] Synthetic example
[0218] Experiment preparation
[0219] 1,6-hexanedithiol (HDT) 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) dibutyl dithiocarbamate (Zn(DTC)2), and n-butylamine (nBA) 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.
[0220] Synthesis Example: Synthesis of Dynamic Chain Extender
[0221]
[0222] 8 g of dynamic chain extender HDT-TU was prepared by reacting 5.1 ml of HDI and 2.7 ml of HDT in a 2:1 molar ratio at 50°C for 1 hour in the presence of Zn(DTC)2. The above preparation method is briefly illustrated in Fig. 2.
[0223] Preparation Example 1: Preparation of Liquid Crystal Vitremer TU_25
[0224]
[0225] A first mixture is produced by mixing RM82, a reactive liquid crystal monomer, and HDT-TU, a dynamic chain extender prepared according to Synthesis Example 1; a second mixture is produced by mixing HDT, 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, HDT-TU, HDT, and PETMP are 1: 0.2: 0.8: 0.05, respectively, and the third mixture further contains 2 wt% of catalyst DPA based on the total weight of RM82, HDT-TU, HDT, and PETMP.
[0226] After cleaning, 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 via a thiol-Michael addition reaction, thereby producing the liquid crystal vitremer TU 0.2 of Example 2. The above preparation method is briefly illustrated in Fig. 3.
[0227] Preparation Examples 2 to 6
[0228] Except for modifying the molar ratios of RM82, HDT-TU, HDT, and PETMP in Preparation Example 1 as shown in Table 1 below, liquid crystal vitremers TU 0.0, TU 0.4, TU 0.6, TU 0.8, and TU 1.0 of Examples 1 and 3 to 6 were prepared in the same manner as Preparation Example 1.
[0229] That is, the liquid crystal vitremers according to Preparation Examples 1 to 6 were synthesized with an excess amount of Thiol relative to Acrylate of about 10 mol% to induce a linked exchange reaction, fixed the amounts of RM82 and PETMP, and adjusted the ratio of dynamic chain extender HDT-TU and chain extender HDT to 0:100 / 20:80 / 40:60 / 60:40 / 80:20 / 100:0 to produce the liquid crystal vitremers as shown below.
[0230] Examples Liquid Crystal Vitremer Acrylate terminated monomer Thiol terminated monomer RM82 (mol ratio) HDT-TU (mol ratio) HDT (mol ratio) PETMP (mol ratio) Example 1 TU 0.01 0.01 0.05 Example 2 TU 0.21 0.20 8 0.05 Example 3 TU 0.41 0.40 6 0.05 Example 4 TU 0.61 0.60 40.05 Example 5 TU 0.81 0.80 20.05 Example 6 TU 1.011 0.00 0.05
[0231] [Evaluation Example 1: Comparison of Hydrogen Bonding Strength According to Composition of Dynamic Chain Extender]
[0232] (Evaluation Method)
[0233] To compare the hydrogen bond strength in the liquid crystal vitrimer according to the composition of the dynamic chain extender, FT-IR was used to identify the hydrogen bond peak formed by C=O in the 1640 cm-1 wavelength band and the hydrogen bond peak formed by NH bonds in the 3300 cm-1 band, and the results are shown in Figure 4.
[0234] (Evaluation Results)
[0235] Figure 4 is a figure showing the absorbance according to wavelength for Examples 1 to 6. Through Figure 4, it can be confirmed that the higher the composition of the dynamic chain extender, the greater the intensity of the hydrogen bond peak, that is, the greater the intensity of the hydrogen bond.
[0236] [Evaluation Example 2: Comparison of Gel Fraction According to Composition of Dynamic Chain Extender]
[0237] (Evaluation Method)
[0238] To compare the gel fraction in the liquid crystal vitremer according to the composition of the dynamic chain extender, a cross-linked thiourethane liquid crystal vitremer film was immersed in chloroform for 24 hours and then dried in a vacuum oven for 24 hours. The masses before and after immersion in chloroform were measured and compared, and the results are shown in Figure 5.
[0239] (Evaluation Results)
[0240] Figure 4 is a figure showing the absorbance according to wavelength for Examples 1 to 6. Through Figure 4, it can be confirmed that the higher the composition of the dynamic chain extender, the greater the intensity of the hydrogen bond peak, that is, the greater the intensity of the hydrogen bond.
[0241] Figure 5 illustrates the gel fractions for Examples 1 to 6. Through Figure 5, it can be seen that the gel fraction gradually increases as the composition of the dynamic chain extender increases. This can be attributed to the fact that physical crosslinking occurs due to hydrogen bonding of the thiourethane, causing the liquid crystal vitremer to form double crosslinks.
[0242] [Evaluation Example 3: Comparison of Thermal Properties According to Composition of Dynamic Chain Extender]
[0243] (Evaluation Method)
[0244] In order to confirm the thermal characteristics according to the composition of the dynamic chain extender, the change in heat quantity according to temperature was confirmed for Examples 1 to 5 using a differential scanning calorimeter (DSC), and the results are shown in Figures 6 and 7.
[0245] (Evaluation Results)
[0246] Figures 6 and 7 illustrate the change in heat quantity according to temperature for Examples 1 to 6.
[0247] Liquid crystal vitremers transform into 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 (Tni). At this temperature, the liquid crystal elastomer changes its orientation at temperatures above Tni and can exhibit actuation behavior accordingly. Through Figure 6, the nematic-isotropic transition temperature can be confirmed, and it can be observed that the higher the composition of the dynamic chain extender, the lower the nematic-isotropic transition temperature becomes. Therefore, it has the effect of enabling shape transformation at relatively low temperatures.
[0248] In the liquid crystal vitremer of the present invention, a crystal structure is formed in the liquid crystal vitremer network due to the chain extender, and the melting temperature (Tm) was measured on DSC. Through Fig. 7, it can be confirmed that Example 1, which does not contain a dynamic chain extender, shows a Tm around 50°C, and as the composition of the dynamic chain extender increases, a Tm is found around 190°C. Therefore, in this case, since Tni is a much lower temperature, crystallinity is maintained, allowing for stable thermal operation. In addition, it can be confirmed that the chain extender and the dynamic chain extender can form different crystal structures.
[0249] [Evaluation Example 4: Comparison of Crystal Structures According to Composition of Dynamic Chain Extender]
[0250] (Evaluation Method)
[0251] In order to confirm the crystal structure according to the composition of the dynamic chain extender, WAXS (wide-angle X-ray scattering) measurements were performed on Examples 1 to 6, and the graph thereof is shown in Fig. 8, and the 2D WAXS pattern is shown in Fig. 9.
[0252] In addition, to confirm the change in the crystal structure of the liquid crystal vitremer as the temperature increases, in-situ WAXS measurements were performed on Examples 1 to 6, and the results are shown in FIG. 10.
[0253] (Evaluation Results)
[0254] Through Figures 8 and 9, it can be seen that the crystal structure present in the liquid crystal vitremer changes as the composition of the dynamic chain extender increases. In TU0.0 of Example 1, which does not contain a dynamic chain extender, four peaks were measured, and it can be seen that as the composition of the dynamic chain extender increases, the intensity of two peaks gradually increases and the remaining two peaks disappear. Through this, it can be seen that the composition of the dynamic chain extender affects the formation of the crystal structure of the liquid crystal vitremer.
[0255] Through Fig. 10, changes in the crystal structure of the liquid crystal vitremer as the temperature increases could be confirmed according to the composition of the dynamic chain extender. In Examples 1 to 3, where the composition of the dynamic chain extender is low, the crystal structure disappears at temperatures above Tm, leaving only amorphous peaks, whereas in Examples 4 to 6, where the composition of the dynamic chain extender is high, it can be confirmed that the crystal structure is maintained even at high temperatures.
[0256] [Evaluation Example 5: Comparison of Thermomechanical Properties According to Composition of Dynamic Chain Extender]
[0257] (Evaluation Method)
[0258] In order to confirm the thermomechanical properties according to the composition of the dynamic chain extender, dynamic mechanical analysis (DMA) was performed on Examples 1 to 6, and the results are shown in Fig. 11.
[0259] (Evaluation Results)
[0260] Through Fig. 11, it can be confirmed that liquid crystal vitremers with a high composition of dynamic chain extenders maintain a higher storage modulus because they have the effect of maintaining their crystal structure even at high temperatures.
[0261] [Evaluation Example 6: Comparison of Mechanical Properties According to Composition of Dynamic Chain Extender]
[0262] (Evaluation Method)
[0263] In order to confirm the mechanical properties according to the composition and crystallinity of the dynamic chain extender, the mechanical properties of Examples 1 to 6 were measured using a Universal Testing Machine (UTM), and the results are shown in FIG. 12, FIG. 13, Table 2, and Table 3.
[0264] (Evaluation Results)
[0265] In FIG. 12, FIG. 13, Table 2, and Table 3, C- represents a sample in which crystallization has been formed, and nC- represents a sample in which crystallization has not been formed. In all examples, it can be confirmed that the sample has higher mechanical properties when crystallization is formed compared to when crystallization is not formed.
[0266] Young's Modulus (MPa)Toughness (MPa)Ultimate Strength (MPa)Failure Strain (%)C-TU0.040.1839.548.336491.2C-TU0.233.4226.629.807354.8C-TU0.427.4519.876.375327 .2C-TU0.615.8315.026.767345.7C-TU0.816.2327.0111.47319.6C-TU1.019.9918.6411.89221.6
[0267] Young's Modulus (MPa)Toughness (MPa)Ultimate Strength (MPa)Failure Strain (%)nC-TU0.01.455.0252.844624.8nC-TU0.21.153.0051.569396.8nC-TU0.41.017.4113.041527 .4nC-TU0.61.727.2452.255554.6nC-TU0.82.278.1614.021413.8nC-TU1.03.639.8475.001341.0
[0268] [Evaluation Example 7: Control of Optical Properties According to Composition of Dynamic Chain Extender]
[0269] (Evaluation Method)
[0270] To compare optical properties according to the composition of dynamic chain extenders, the properties of liquid crystal molecules aligning in a specific direction were confirmed for Examples 1 to 6, and the results are shown in FIG. 14. For the liquid crystal vitremers of each example, samples in the polydomain state were stretched 100% uniaxially and stored for 12 hours, after which optical properties resulting from double refraction were measured using a polarizing optical microscope.
[0271] In addition, for Examples 1 and 6, the double refraction of the aligned liquid crystal vitremer films was confirmed under a polarizing optical microscope, and the results are shown in FIG. 15. (Scale bar = 1000 μm)
[0272] (Evaluation Results)
[0273] FIG. 14 is a polar coordinate graph showing the relative difference in transmitted light brightness according to the rotation angle between polarizers for Examples 1 to 6. It can be seen that as the composition of the dynamic chain extender increases, the bright optical characteristics decrease and the alignment of the liquid crystal is restricted, confirming that the composition of the dynamic chain extender affects the alignment performance of the liquid crystal. Additionally, through FIG. 15, the alignment of liquid crystal molecules can be confirmed more clearly.
[0274] [Evaluation Example 8: Control of Thermal Actuation Characteristics According to Composition of Dynamic Chain Extender]
[0275] (Evaluation Method)
[0276] After 100% uniaxial stretching the liquid crystal vitremers of Examples 1 to 6 and fixing them at room temperature, T ni When heated above, 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. 16. At this time, the driving strain can be controlled by the tensile strain applied initially.
[0277] (Evaluation Results)
[0278] Through Fig. 16, it can be seen that in the case of an example with a low composition of dynamic chain extender, a large driving deformation occurs with a normalized dimension perpendicular to the aligned direction of about 1.7 or more. As the composition of the dynamic chain extender increases, it can be confirmed that a driving deformation occurs with a normalized dimension perpendicular to the aligned direction of about 1.3 or more, even though the movement of the chains and the orientation of the liquid crystal are restricted because the crystal structure is maintained even at high temperatures.
[0279] [Evaluation Example 9: Reprocessing and Self-Healing Properties of Liquid Crystal Vitremers]
[0280] (Evaluation Method)
[0281] To compare the self-healing performance of liquid crystal vitremers using heat, the liquid crystal vitremers of Example 1 and Example 3 were cut and hot-pressed at 150°C at 10 MPa for 30 minutes, and the results are shown in FIG. 17.
[0282] For the liquid crystal vitremers before and after the above hot-press, i.e., the original film and the reprocessed film, toughness was measured using a UTM, and the results are shown in Fig. 18, and self-healing efficiency was measured and is shown in Table 4.
[0283] (Evaluation Results)
[0284] Through Fig. 17, it can be seen that the liquid crystal vitremer without a dynamic chain extender does not undergo reprocessing and is not formed into a film, whereas the film containing a dynamic chain extender undergoes a dynamic exchange reaction and is reprocessed and restored into a uniform film.
[0285] In addition, through Figure 18 and Table 4, the toughness and self-healing efficiency of the original film and the reprocessed film of Example 3 were checked, and it was confirmed that more than 80% of the toughness measured in the original film was recovered.
[0286] Original film tension of Example 3 (MPa) 19.87 MPa Reprocessed film tension of Example 3 (MPa) 16.31 MPa Self-healing efficiency of Example 3 (%) 82.1 %
[0287] [Evaluation Example 10: Molecular Orientation Programming of Liquid Crystal Vitreamers]
[0288] (Evaluation Method)
[0289] For the liquid crystal vitremers of Examples 1 and 3, programming into a specific shape was performed under conditions of 150°C for 1 hour, and after removing the shape through shape deformation, the nematic-isotropic transition temperature (T ni Changes were observed by applying a temperature above ) and the results are shown in Fig. 19.
[0290] (Evaluation Results)
[0291] Through FIG. 19, the liquid crystal vitremer of Example 1, which does not contain a dynamic chain extender, after removing the shape, T ni Above, when heat is applied, it returns to its initial rectangular shape, but the liquid crystal vitremer of Example 3 containing a dynamic chain extender T after the shape is removed niAs described above, it can be confirmed that applying heat causes it to return to the programmed shape. In other words, it can be seen that it returns from the existing rectangular shape to the programmed twisted shape, and it can be confirmed that repetitive molecular orientation reprogramming is possible in various forms thereafter.
[0292] In conclusion, the present invention provides a liquid crystal vitremer utilizing thiourethane dynamic covalent bonds and hydrogen bonds that can be rapidly activated at relatively low temperatures and utilize inexpensive commercial monomers, as well as a method for manufacturing the same. Furthermore, the liquid crystal vitremer of the present invention can maintain crystallinity and possess stable thermal drive because its nematic-isotropic transition temperature is much lower than the melting temperature.
[0293] In addition, as can be seen from the previous evaluation examples, by controlling the composition of a dynamic chain extender containing a thiourethane group, the hydrogen bonding strength, gel fraction, thermal properties, crystal structure, thermomechanical properties, mechanical properties, and optical properties of the liquid crystal vitremer can be controlled. Furthermore, it has reprocessing and self-healing properties and allows for repetitive molecular orientation programming.
[0294] Therefore, it can be seen that the liquid crystal vitremer has stable thermal driving properties and can be controlled with optimized thermal properties, crystal structure, thermomechanical properties, mechanical properties, and optical properties, while also possessing reprocessing and self-healing properties, making it suitable for use in composite materials.
[0295] 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.
[0296] 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 technical scope of protection of the present disclosure should be determined by the technical spirit of the appended claims.
Claims
1. 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82), a reactive liquid crystal monomer; A dynamic chain extender represented by Formula 1 below; Chain extender containing a dithiol terminal group; A crosslinking agent containing tetrathiol terminal groups; and a liquid crystal vitrimer formed by polymerizing a catalyst: <Equation 1> Among the above Equation 1, X 11 is an alkylene group, and X 12 is a hexylene group.
2. In Paragraph 1, The above X 11 is a liquid crystal vitrimer that is a hexylene group.
3. In Paragraph 1, The above chain extender is a liquid crystal vitremer represented by the following formula 2: <Equation 2> Among the above Equation 2, X 22 It is an alkylene group.
4. In Paragraph 3, The above X 22 A liquid crystal vitrimer that is a hexylene group.
5. In Paragraph 1, The above crosslinking agent is a liquid crystal vitremer represented by the following formula 3: <Equation 3> Among the above Equation 3, X 31 , X 32 , X 33 and X 34 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. 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82), a reactive liquid crystal monomer; and A first mixture generation step (S201) in which a dynamic chain extender represented by the following formula 1 is mixed, and Chain extender containing a dithiol terminal group; A crosslinking agent containing a tetrarathiol terminal group; and A method for manufacturing a liquid crystal vitreamer comprising a step (S202) of producing a second mixture mixed with a catalyst: <Equation 1> Among the above Equation 1, X 11 is an alkylene group, and X 12 is a hexylene group.
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 vitreamer, 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 casting step.