JP7546263B2 - Manufacturing method and driving method for electric field deformation elastomer - Google Patents

Description

Article 30, paragraph 2 of the Patent Act applies. Publication name: 66th Spring Meeting of the Japan Society of Applied Physics, Proceedings of the Lecture Published by: Japan Society of Applied Physics Publication date: February 25, 2019 [Publication, etc.] Publication name: 2019 Japanese Liquid Crystal Society Symposium, Proceedings Published by: Japan Liquid Crystal Society Publication date: August 19, 2019 [Publication, etc.] Meeting name: Innovation Japan 2019 (Tokyo Big Sight, 1-2-33 Aomi, Koto-ku, Tokyo) Date held: August 29, 2019

The present invention relates to an elastomer that deforms in response to an electric field.

Liquid crystal elastomers are elastomers that deform in response to an electric field. Liquid crystal elastomers have both the properties of liquid crystals and elastomers, and while they are solids with rubber-like elasticity, they also have the electric field responsiveness that is a property of liquid crystals. Because of these unique properties, they are expected to be used in artificial muscles and actuators. They are also attracting attention as a material for film-type displays, when transparent and flexible electrodes are coated on both sides of a film-like liquid crystal elastomer.

In order to make liquid crystal elastomers more widely applicable, they are required to deform in response to an electric field over a wider temperature range. In response to this demand, the inventors have created a liquid crystal elastomer that deforms in response to an electric field in the temperature range of the isotropic phase (Patent Document 1).

JP 2018-131496 A

Incidentally, a unique property of liquid crystals is the "flexoelectric effect." This is a phenomenon in which polarization occurs when liquid crystal molecules bend or spray in the nematic liquid crystal phase. Because the nematic liquid crystal phase has fluidity, these deformations and the resulting polarization cannot be fixed, making it difficult to utilize the polarization phenomenon caused by the flexoelectric effect as a function.

The present invention aims to provide a liquid crystal elastomer that can utilize the deformation caused by the electric field response of a liquid crystal polymer having a nematic liquid crystal phase by crosslinking the polymer while bending and spreading the polymer. This fixes the flexoelectric effect and produces macroscopic polarization.

In order to solve the above problems, the present invention provides the following electric field deformation elastomers. That is, as a first invention, the present invention provides an electric field deformation elastomer that contains polarized organic polymers in a fixed or semi-fixed state with the polarization direction aligned in the majority of the organic polymer, and that deforms when an electric field is applied.

As a second invention, the present invention provides an electric field deformation elastomer according to the first invention, in which the organic polymer comprises a backbone polymer, which is a polymer that functions as a structural material, polarized organic molecules that are covalently bonded to the backbone polymer as side chains and are incompatible with the polymer, and crosslinker molecules that bridge the backbone polymers.

As a third invention, the present invention provides an electric field deformable elastomer according to the second invention, in which the polarized organic molecules are liquid crystal molecules.

As a fourth invention, the present invention provides an electric field deformable elastomer according to the second or third invention, in which the polarized organic molecules have a molecular shape that allows the polarization direction to be aligned by the applied stress.

The fifth invention provides an electric field deformation elastomer according to the fourth invention, which is dependent on the third invention, in which the alignment is an alignment that appears in a nematic phase that corresponds to the phase transition between a smectic A phase and an isotropic phase.

As a sixth invention, the present invention provides an electric field deformation elastomer according to the third invention, or the fourth or fifth invention dependent on the third invention, in which the liquid crystal molecules are mesogens and/or liquid crystal molecules having a mesogen skeleton.

As a seventh invention, a method for producing an electric field deformable elastomer is provided, which includes a reaction initiation step of obtaining a reaction structure by initiating a reaction between a backbone polymer to function as an elastic structural material, a wedge-shaped liquid crystal molecule covalently bonded to the backbone polymer, and a crosslinker molecule, which is a molecule that bridges between the backbone polymers, in a volatile solvent, and a spreading deformation imparting step of applying a tensile stress to the reaction structure to impart a spreading deformation before the volatile solvent is completely evaporated after the reaction is started.

As an eighth invention, the present invention provides a method for producing an electric field deformable elastomer according to the seventh invention, which further includes a fixing step of volatilizing the remaining volatile solvent after the spreading deformation imparting step to fix the alignment of the wedge-shaped liquid crystal molecules to which the tensile stress of the spreading deformation is applied.

As a ninth invention, a method for producing an electric field deformable elastomer is provided, which includes a reaction initiation step of obtaining a reaction structure by initiating a reaction between a backbone polymer to function as an elastic structural material, banana-shaped liquid crystal molecules covalently bonded to the backbone polymer, and crosslinker molecules that crosslink between the backbone polymers in a volatile solvent, and a bending deformation imparting step of applying a tensile stress to the reaction structure to impart a bending deformation before the volatile solvent completely evaporates after the reaction is initiated.

As a tenth invention, the present invention provides a method for producing an electric field deformable elastomer according to the ninth invention, which further includes a fixing step of volatilizing the remaining volatile solvent after the bending deformation imparting step to fix the alignment of the banana-shaped liquid crystal molecules to which the tensile stress of bending deformation is applied.

In addition, as an eleventh invention, there is provided a method for driving an electric field deformable elastomer manufactured by the method for manufacturing an electric field deformable elastomer described in any one of the seventh to tenth inventions, the method comprising an energy imparting step of imparting energy to the manufactured electric field deformable elastomer, and an electric field applying step of applying an electric field to the electric field deformable elastomer.

The present invention, configured as described above, can provide an electric field deformable elastomer that can fix the flexoelectric effect, produce macroscopic polarization, and utilize the deformation caused by the electric field response of that polarization.

Diagram for outlining liquid crystal elastomers A simplified schematic diagram of the liquid crystal elastomer structure Conceptual diagram explaining the flexoelectric effect in the case of wedge-shaped liquid crystal molecules Conceptual diagram explaining the flexoelectric effect in the case of banana-shaped liquid crystal molecules FIG. 1 is a diagram showing an embodiment of synthesizing a liquid crystal elastomer using the molecules exemplified as a backbone polymer, liquid crystal molecules, and crosslinker molecules. A schematic diagram showing an example of a liquid crystal elastomer obtained by applying a spreading deformation. A flow diagram showing a preferred embodiment of a method for producing an electric field deformable elastomer. Conceptual diagram for explaining the deformation applying step Flow diagram showing how to drive an electric field deformation elastomer Schematic diagram of the observation cell for observing deformation in response to an electric field Schematic diagram showing the results of observing bending deformation due to application of an electric field to a specimen that has been deformed by spreading Figure showing the results of electron microscope observation Conceptual diagram showing the state of molecules

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to these embodiments, and can be embodied in various forms without departing from the spirit of the present invention.
<Embodiment>
<Configuration>

Using Figure 1, we will outline liquid crystal elastomers as a representative example of materials that can become electric field deformable elastomers. Liquid crystal elastomers are substances in which liquid crystal molecules that impart electric field responsiveness are bonded to elastomers. Note that the electric field deformable elastomers of the present invention are not limited to liquid crystal elastomers, but broadly include elastomers that are formed by bonding molecules that can impart electric field responsiveness to elastomers, and that deform in response to an electric field. Note that in the following explanation, liquid crystal elastomers to which liquid crystal molecules are bonded will mainly be described as electric field deformable elastomers.

As shown in Figure 1, liquid crystal elastomers are formed by chemically bonding an elastomer (shown on the left side of the figure) with liquid crystal molecules (shown on the right side of the figure). Elastomers are generally cross-linked polymers and have elasticity.

Liquid crystals are a state that appears as an intermediate state between a crystal and a liquid in certain molecules. As shown in the figure, the liquid crystal phases are the isotropic phase (a), in which the molecules have no orientational order, the nematic phase (b), in which the molecules have orientational order but no three-dimensional positional order, and the smectic phases (c, d), which have a layered structure. Figure 13 is a conceptual diagram that shows a more three-dimensional view, showing the isotropic phase (a), nematic phase (b), smectic A phase (c), and crystal (d).

Figure 2 is a conceptual diagram showing the structure of a liquid crystal polymer in a simplified manner. Liquid crystal polymers can be broadly divided into main chain and side chain types. As shown in Figure 2(a), main chain liquid crystal polymers have a structure in which liquid crystal molecules 0201 having a mesogenic skeleton in which a rod-shaped or plate-shaped rigid group (such as an aromatic ring) called a mesogen or mesogenic group is introduced into the skeleton are serially incorporated into the main chain 0202. As shown in Figure 2(b), side chain liquid crystal polymers have one end of a liquid crystal molecule 0203 bonded to the main chain 0204. Liquid crystal elastomers have a structure in which the main chains of the above-mentioned liquid crystal polymers are linked together by cross-linking molecules (cross-linked).

As shown in FIG. 2, the degree of restraint of the liquid crystal polymer by the main chain is lower in the side-chain type liquid crystal polymer than in the main-chain type liquid crystal polymer, so the side-chain type liquid crystal elastomer has better molecular mobility of the liquid crystal molecules than the main-chain type liquid crystal elastomer, and is more responsive to external stimuli such as fluctuating magnetic fields and electric fields. It is preferable that the liquid crystal elastomer in the present invention is also a side-chain type liquid crystal elastomer.

The liquid crystal elastomer of the present invention contains polarized organic polymers in a fixed or semi-fixed state with the polarization direction aligned in the majority of the organic polymers, and is deformed by an applied electric field.

Organic polymers refer to polymers that are the basic elements that make up liquid crystal elastomers, and consist of a main chain (backbone polymer), liquid crystal molecules (polarized organic molecules) that are bonded to the main chain and side chains, and crosslinking molecules (crosslinker molecules) that bridge the main chains. Liquid crystal elastomers are formed by polymerizing and crosslinking such organic polymers.

The polarization of an organic polymer refers to the electric dipole moment that occurs as a result of certain parts of the organic polymer carrying an electric charge. For example, liquid crystal molecules may have a large electric dipole moment due to their anisotropic shape. Wedge-shaped and banana-shaped liquid crystal molecules are known examples of anisotropic shapes.

Figure 3 is a conceptual diagram explaining the flexoelectric effect when wedge-shaped liquid crystal molecules are in the nematic phase. As shown in Figure 3(a), each wedge-shaped liquid crystal molecule 0301 has an electric dipole moment 0302 (is polarized) as indicated by the arrow in the figure. Under normal conditions, the liquid crystal polymers are arranged in alternating directions, so that the individual electric dipole moments cancel each other out and there is almost no overall polarization.

However, as shown in Figure 3(b), the expansion and deformation causes the electric dipole moments of the liquid crystal polymers to align. When the polarization directions of the liquid crystal polymers are aligned in this way, the electric dipole moments of the liquid crystal polymers do not cancel each other out, and an overall polarization 0303 is expressed.

Figure 4 is a conceptual diagram explaining the flexoelectric effect in the case of banana-shaped liquid crystal molecules. As shown in Figure 4(a), each banana-shaped liquid crystal molecule 0401 has an electric dipole moment 0402, as indicated by the arrow in the figure. Under normal conditions, the liquid crystal polymers are arranged in alternating directions, so that the individual electric dipole moments cancel each other out and almost no overall polarization is observed.

However, as shown in Figure 4(b), bending deformation causes the electric dipole moments of the liquid crystal polymers to align. When the polarization directions of the liquid crystal polymers are aligned in this way, the electric dipole moments of the liquid crystal polymers do not cancel each other out, and an overall polarization 0403 is expressed.

In this way, liquid crystal molecules with a molecular shape of a wedge or banana shape can align their polarization direction when stress is applied. A typical example of a wedge-shaped liquid crystal molecule is a cholesteric liquid crystal molecule, which is a compound with a steroid skeleton in which three chair-shaped six-membered rings and one five-membered ring are connected. It may also be a polycyclic compound to which a cyclic compound is further bonded. Moreover, banana-shaped liquid crystal molecules are liquid crystal molecules in which the two mesogen groups are linked through semi-rigid groups in a way that they are not on the same line, and have a molecular structure that is bent or curved like a banana.

In conventional liquid crystal elastomers, the spreading and bending deformations described above cause the majority of the liquid crystal molecules to align so that their polarization directions are aligned. However, when the forces causing the spreading and bending deformations cease to act, the polarization directions of the individual liquid crystal molecules cancel each other out, as shown in Figures 3(a) and 4(a), and no polarization occurs overall.

In contrast, in the present invention, the macroscopic polarization is fixed as shown in Figures 3(b) and 4(b). A liquid crystal elastomer that exhibits such characteristics can be deformed by applying an electric field. Fixing the macroscopic polarization can be achieved by producing a liquid crystal elastomer through a cross-linking reaction while expanding or bending.

The organic polymer that constitutes the electric field deformation elastomer of the present invention is composed of a backbone polymer, polarized organic molecules, and crosslinker molecules.

The backbone polymer is a polymer that functions as a structural material. In other words, it constitutes the main chain in the structure of the electric field deformation elastomer. For example, polymethyl hydrosiloxane can be used. Such backbone polymers are polymerized through siloxane bonds (Si-O-Si) to form polymers.

Polarized organic molecules are covalently bonded to the backbone polymer as side chains and are incompatible with the polymer. Polarized organic molecules are organic molecules that exhibit polarization. A representative example of a polarized organic molecule is a liquid crystal molecule. As the liquid crystal molecule, a cholesterol derivative monomer (undecylenic acid cholesteryl ester) that exhibits one or more of the following phases can be used: nematic phase, cholesteric phase, and smectic phase (either A phase, C phase, or both).

Compatibility is a term used to describe the degree to which polymers mix together, and when both polymers are evenly mixed together, they are said to be in a highly compatible state. Incompatibility means that the polymer and liquid crystal molecules are difficult to mix evenly, and separation from each other or aggregation of either may occur.

Liquid crystal molecules are also covalently bonded to the backbone polymer as side chains, for example, by covalent bonds to silicon (Si) in the polysiloxane that makes up the backbone polymer.

Crosslinker molecules are molecules that bridge between backbone polymers. For example, bifunctional enoyloxyphenyl (undecylenic acid 4-undec-10-enoyloxy-phenyl ester (hereinafter referred to as U10)) can be used.

Figure 5 shows how a liquid crystal elastomer is synthesized using the molecules exemplified above as the backbone polymer, liquid crystal molecule, and crosslinker molecule. As shown in the figure, (1) the backbone polymer, (2) the liquid crystal molecule (cholesterol derivative monomer), and (3) the crosslinker molecule are dissolved in a toluene solvent, and (4) a side-chain liquid crystal elastomer can be obtained by a hydrosilylation reaction.

As shown in (5), the cholesterol derivative monomer has polarity due to the ester group (-coo-). It has an electric dipole moment P _i , and polarization P = ΣP _i occurs during the expansion deformation. The semi-empirical molecular orbital calculation of the liquid crystal elastomer obtained in the test described below confirmed the existence of an electric dipole moment of 1.1 debye. As shown in (4), the liquid crystal molecules are bonded to the silicon (Si) of the backbone polymer, and the crosslinker molecules are bonded to the silicon (Si) of the backbone polymer to form a crosslink.

The characteristic process for producing a liquid crystal elastomer with fixed or semi-fixed polarization that deforms under an applied electric field is to apply a tensile stress to the reaction structure, which is the structure generated by the reaction, to cause a spreading deformation after the reaction has started and before the solvent is evaporated and desolvated. As described above, when the wedge-shaped liquid crystal molecules are subjected to a spreading deformation, the polarization direction of each wedge-shaped liquid crystal molecule becomes aligned. Then, when the crosslinking reaction proceeds in a state in which the spreading deformation has been applied, each of the aligned wedge-shaped liquid crystal molecules is fixed. As a result, the overall polarization is fixed.

Figure 6 is a conceptual diagram showing an example of a liquid crystal elastomer obtained by applying a spreading deformation. This liquid crystal elastomer was obtained by continuing the reaction until the solvent was almost completely evaporated while pulling both ends of a reaction structure that had reacted to a certain extent and turned into a film. The cholesterol derivative used as the liquid crystal molecule has a wedge-shaped molecular shape.

Figure 6(a) is a conceptual diagram showing the behavior of the liquid crystal elastomer in the temperature range of the smectic A phase (40°C to 120°C), and Figure 6(b) shows the behavior of the liquid crystal elastomer in the temperature range of the isotropic phase (120°C and above).

In the temperature range of the smectic A phase shown in Figure 6(a), the layer structure is maintained even at the fixed end of the liquid crystal elastomer enclosed by the ellipse in the figure, and even if it is deformed by spreading, the polarization direction of each liquid crystal molecule does not become aligned, so no macroscopic polarization is expressed, and no deformation occurs even when an electric field is applied.

In the temperature range of the isotropic phase shown in Fig. 6(b), the layer structure is lost, but the orientation order of the liquid crystal molecules remains, and it is believed that the alignment of the liquid crystal molecules that appears in the nematic phase exists. Therefore, as shown in Fig. 6(c), which shows an enlarged view of the vicinity of this fixed end, the wedge-shaped liquid crystal molecules spread at this fixed end, inducing deformation, and the state in which the electric dipole moment P of each liquid crystal molecule is aligned due to the flexoelectric effect is fixed by cross-linking, resulting in the appearance of macroscopic polarization.
<Production Method>

Figure 7 is a flow diagram showing a preferred embodiment of the method for producing the electric field deformable elastomer described above. This method for producing an electric field deformable elastomer includes a reaction initiation step 0701, a deformation imparting step 0702, and a fixing step 00703. It is possible to produce the electric field deformable elastomer according to the present invention by performing only the reaction initiation step and the deformation imparting step.

First, in the reaction initiation step 0701, a reaction is initiated in a volatile solvent between a backbone polymer to function as an elastic structural material, wedge-shaped liquid crystal molecules covalently bonded to the backbone polymer, and crosslinker molecules that bridge between the backbone polymers to obtain a reaction structure. The backbone polymer, wedge-shaped liquid crystal molecules, and crosslinker molecules are as described above.

Volatile solvents are not particularly limited, but examples that can be used include toluene, xylene, acetone, methyl ethyl ketone, cyclohexane, n-hexane, n-heptane, butanol, and isopropanol (IPA).

In the reaction initiation step, for example, polymethylhydroxysiloxane (polymethyl hidrosiloxane: 2.0 mmol) as a backbone polymer, cholesterol derivative monomer (undecylenic acid cholesteryl ester: 1.6 mmol) as a wedge-shaped liquid crystal molecule containing mesogens, and bifunctional enoyloxyphenyl (U10: 2 mmol) as a crosslinker molecule are dissolved in toluene, a volatile solvent, and a hydrosilylation reaction is carried out using a platinum catalyst to obtain a reaction structure.

In the deformation step 0702, a tensile stress is applied to the reaction structure to cause it to expand and deform before the volatile solvent completely evaporates after the start of the reaction (in this example, about 4 hours have passed at 40°C). For example, the reaction structure is formed into a thin slice, and each of the opposing edges of the slice is held with adhesive tape or the like, and stress is applied in a direction in which the edges move away from each other. In this example, uniaxial stretching (59.2 mN/ ^mm2 , about 12 hours) is performed at room temperature (25°C).

Figure 8 is a conceptual diagram for explaining the deformation imparting step. As shown in Figure 8(a), both ends of the reactive structure piece 0801 before the application of tensile stress are grasped 802, and tensile stress is applied in the direction in which the respective ends move apart 0803. By applying such tensile stress, as shown in Figure 8(b), the reactive structure piece 0801 is stretched and thinned except for the ends. As a result, the edge region of the piece is expanded and deformed. As the reaction progresses, the backbone polymers are crosslinked by the crosslinker molecules, giving it elasticity as an elastomer, and the alignment of the wedge-shaped liquid crystal molecules is fixed in a state in which the polarization direction of the wedge-shaped liquid crystal molecules is aligned in the part where the expansion deformation occurs.

The expanded and deformed portion of the electric field deformable elastomer obtained by these steps exhibits polarization in the isotropic phase temperature region and deforms in response to an electric field.

In addition to the above two steps, a fixing step 0703 is performed to fix the alignment of the wedge-shaped liquid crystal molecules with the same polarization direction. In other words, after the deformation step, a fixing step is provided in which the remaining volatile solvent is volatilized to spread and fix the alignment of the wedge-shaped liquid crystal molecules to which the tensile stress of deformation is applied. By leaving it at room temperature for about a week (about 4 to 8 days), the desolvation and reaction are completed, and the production of the electric field deformation elastomer is more complete.

This method for producing an electric field deformation elastomer can also be applied when banana-shaped liquid crystal molecules are used, and by replacing the wedge-shaped liquid crystal molecules in each step with banana-shaped liquid crystal molecules and proceeding with the reaction while applying a stress that gives a bending deformation instead of a spreading deformation (bending deformation imparting step), an electric field deformation elastomer can be produced in which the banana-shaped liquid crystal molecules are aligned in a fixed arrangement with the polarization direction fixed. It is also preferable to further include a fixing step.
<Driving method>

It is also possible to provide a method for driving an electric field deformable elastomer manufactured by the above-mentioned manufacturing method. FIG. 9 is a flow diagram showing a method for driving an electric field deformable elastomer. As shown in FIG. 9, this driving method includes an energy application step 0901 and an electric field application step 0902.

The energy application step 0901 is a step of applying energy to the electric field-deformable elastomer produced. The applied energy is the energy required to increase the mobility of the polarized organic molecules that make up the produced electric field-deformable elastomer, making them more responsive to an electric field. For example, when a liquid crystal elastomer is produced using a cholesteric derivative monomer with a wedge-shaped molecular shape, heating is performed to approximately 120°C or higher. By applying energy in this manner, good electric field response is achieved in polarization due to the flexoelectric effect caused by the spreading deformation. Energy is applied in the same manner in the case of an electric field-deformable elastomer using liquid crystal molecules with a banana-shaped molecular shape.

The electric field application step 0902 is a step of applying an electric field to the electric field deformable elastomer to which energy has been applied in the energy application step. The energy application step causes polarization in the electric field deformable elastomer. By applying an electric field to this electric field deformable elastomer, electric field responsive deformation can be brought about. Electric field deformable elastomers that deform in response to an electric field are expected to be used in various fields such as actuators and artificial muscles.
<Test>

Regarding the electric field deformation elastomers explained so far, a representative liquid crystal elastomer was synthesized and subjected to testing. The results are shown below.

Polymethylhydroxysiloxane (2.0mmol) as a backbone polymer, cholesterol derivative monomer (undecylenic acid cholesteryl ester: 1.6mmol) as a liquid crystal molecule containing mesogens, and bifunctional enoyloxyphenyl (U10: 2mmol) as a crosslinker molecule were dissolved in toluene solvent and hydrosilylated. The synthesized product was removed before the reaction was completed (40℃, 4 hours), and the reaction was continued while uniaxially stretching (59.2mN/mm ² , 12 hours) at room temperature (25℃) to obtain an oriented sample (width 2.3mm, length 8.5mm, thickness 0.6mm). After leaving it at room temperature for about one week to remove the solvent and complete the reaction, it was subjected to measurement. The phase series of the sample was [g 33 SmA*120 I (in oC)]. Using this sample, X-ray diffraction was performed to examine the molecular arrangement, and electric field response deformation was measured.

Electric-field-induced deformation was observed by fixing one end of the sample (electrically deformable elastomer: the figure shows the thickness direction) with Kapton tape in an observation cell filled with silicone oil between two pieces of ITO glass as shown in Figure 10. The distance between the ITO glasses was controlled using a silicone rubber spacer (thickness 1 mm), and the shape change was recorded using a microscope observation system with a CCD (objective lens magnification: 10x). The shape change was evaluated from the images obtained from the microscope observation system with a CCD.

The electric dipole moment along the molecular long axis of the cholesterol derivative monomer was calculated after optimizing the molecular structure by the semiempirical molecular orbital method using the PM6 method of the software package Gaussian 09 Revision E.01.
<Results and Discussion>

Figure 11 is a conceptual diagram showing the results of observing the bending deformation of a specimen that has been deformed by spreading due to the application of an electric field. As shown in the figure, a bending deformation of about ±0.15 mm in the x direction was visually observed when an electric field of ±1 kV/mm was applied to the specimen that has been deformed by spreading (the end of the specimen that has been deformed uniaxially) in the temperature range of about 110°C to about 150°C. Since the deformation direction reverses depending on the electric field direction, this is thought to be a polar electric field response.

Figure 12 shows the results of observation with an electron microscope. In order to confirm the spreading deformation at the end of the sample, a polarizing microscope was used for observation. The end of the sample was observed under crossed Nicols, and the direction of the optical axis was confirmed to have changed by about 11 degrees due to spreading. X-ray diffraction also confirmed a change in the molecular long axis due to spreading deformation.

As described above, polar deformation was confirmed in the liquid crystal elastomer that had undergone expansion deformation in the heating temperature range. Furthermore, the generation of static electricity was observed. The generation of polarization is thought to be the cause of the polar deformation and the generation of static electricity. The cholesterol derivative, which is the mesogen used in this study, has a wedge-shaped molecular shape as shown in Figure 5, and it is thought that polarization occurred due to the flexoelectric effect under expansion deformation, as shown in Figure 6 (c).

Since the presence of an electric dipole moment on the molecular long axis is essential for polarization to occur, calculations using the semi-empirical molecular orbital method revealed that an electric dipole moment of about 1.1 debye exists from the mesogen end toward the main chain, as shown in Figure 5. It is believed that this dipole moment spreads and aligns due to deformation, as shown in Figure 6 (c), resulting in macroscopic polarization. The direction of this polarization coincided with the polarity direction of the observed electric field-induced deformation.

In addition, in the above-mentioned temperature range, the orientation order parameter S=0.1 to 0.2 remains, so it is considered to be in a nematic state, and therefore polarization is thought to have occurred due to the flexoelectric effect.
＜Effects＞

The liquid crystal elastomer of the present invention can provide a liquid crystal elastomer that can fix the flexoelectric effect, produce macroscopic polarization, and utilize the deformation caused by the electric field response of the polarization.

0201 Liquid crystal molecule 0202 Main chain 0203 Liquid crystal molecule 0204 Main chain

Claims (5)

a reaction initiation step of initiating a reaction between a backbone polymer to function as an elastic structural material, a wedge-shaped liquid crystal molecule covalently bonded to the backbone polymer, and a crosslinker molecule which is a molecule that crosslinks between the backbone polymers in a volatile solvent to obtain a reaction structure;
a spreading deformation imparting step of applying a tensile stress to the reaction structure to impart a spreading deformation to the reaction structure before the volatile solvent is completely volatilized after the start of the reaction;
having
The method for producing an electric field deformable elastomer comprises expanding and deforming the reaction structure to crosslink and become polarized. 2. The method for producing an electric field deformation elastomer according to claim 1 , further comprising a fixing step of volatilizing the remaining volatile solvent after the spreading deformation imparting step, thereby fixing the alignment of the wedge-shaped liquid crystal molecules to which the tensile stress of the spreading deformation has been applied. a reaction initiation step of initiating a reaction between a backbone polymer to function as an elastic structural material, a banana-shaped liquid crystal molecule covalently bonded to the backbone polymer, and a crosslinker molecule which is a molecule that crosslinks between the backbone polymers in a volatile solvent to obtain a reaction structure;
a bending deformation imparting step of applying a tensile stress to the reaction structure to impart a bending deformation before the volatile solvent is completely evaporated after the start of the reaction;
having
The method for producing an electric field deformable elastomer comprises bending and deforming the reaction structure to crosslink and polarize it. The method for producing an electric field deformation elastomer according to claim 3 , further comprising a fixing step of volatilizing the remaining volatile solvent after the bending deformation imparting step to fix the alignment of the banana-shaped liquid crystal molecules to which the tensile stress of bending deformation is applied. A method for driving an electric field deformation elastomer produced by the method for producing an electric field deformation elastomer according to any one of claims 1 to 4 , comprising the steps of:
An energy application step of applying energy to the electric field deformation elastomer produced above;
An electric field application step of applying an electric field to the electric field deformable elastomer;
A method for driving an electric field deformable elastomer having the above structure.

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