Shape memory material, method for producing the same, and article using the same

Abstract

To provide a shape memory material using an ion gel, a method for producing the same, and an article using the material.SOLUTION: A shape memory material of the present invention comprises an ion gel including a polymer compound having a number average molecular weight of 4.0×105 or more and 1.0×107 or less, and an ionic liquid, wherein the anion of the ionic liquid is represented by formula (1), and the mass ratio of the content of the polymer compound to the content of the ionic liquid is 0.45 or more and less than 4.0, wherein n and m are each an integer of 1 or more, and n+m falls within the range of 3 or more and 10 or less.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a shape memory material using an ion gel, a method for producing the same, and an article using the same.

Background Art

[0002] Recently, an ion gel obtained by curing a composition containing a radically polymerizable compound, a radical polymerization initiator, and an ionic liquid, wherein the mass ratio of the content of the radical polymerization initiator to the content of the radically polymerizable compound is 5×10 -5 ~5×10 -3 has been developed (see, for example, Patent Document 1). According to Patent Document 1, such an ion gel has excellent moldability and can be used as a solid electrolyte and an actuator using the same.

[0003] Another use of the ion gel is a coating composition (see, for example, Patent Document 2). Patent Document 2 discloses a coating composition containing a polymer compound having a number average molecular weight of 5.0×10 5 ~1.0×10 7 , an ionic liquid, and a solvent, wherein the mass ratio of the content of the polymer compound to the content of the ionic liquid is 0.15 or more and less than 1.0, and the film obtained thereby has excellent strength and self-healing performance.

[0004] However, the physical properties of ion gels are not yet fully understood, and further applications are expected.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] From the above, an object of the present invention is to provide a shape memory material using an ion gel, a method for producing the same, and an article using the same.

Means for Solving the Problems

[0007] The shape memory material according to the present invention is composed of an ion gel containing a polymer compound having a number average molecular weight of 4.0×10 5 or more and 1.0×10 7 or less and an ionic liquid. The anion of the ionic liquid is represented by the formula (1), and the mass-based ratio of the content of the polymer compound to the content of the ionic liquid is 0.45 or more and less than 4.0, thereby solving the above problems.

Chemical formula

[0008] The shape memory material of the present invention is composed of an ion gel containing a polymer compound having a number average molecular weight of 4.0×10 5 or more and 1.0×10 7 or less, and an ionic liquid of an anion represented by the formula (1). The mass ratio of the content of the polymer compound to the content of the ionic liquid is 0.45 or more and less than 4.0. When the ion gel satisfies specific conditions, the ion gel has excellent shape retention ability and shape recovery ability and functions as a shape memory material. Since the shape memory material of the present invention is composed of an ion gel, it has an elongation rate of 100% or more and excellent moldability. Since the shape memory material of the present invention contains an ionic liquid, it is stable even under special environments such as under vacuum, high pressure, or in water. Further, since the polymer compound and the ionic liquid in the shape memory material of the present invention are uncrosslinked, recycling by thermoforming or the like is also possible. The shape memory material of the present invention is applied to parts of daily necessities, medical products, devices, etc.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same elements are denoted by the same reference numerals, and the description thereof will be omitted.

[0011] In addition, in this specification, “(meth)acrylate” represents both acrylate and methacrylate, or either one, and “(meth)acrylic” represents both acrylic and methacrylic, or either one. Further, “(meth)acryloyl” represents both acryloyl and methacryloyl, or either one.

[0012] (Embodiment 1) In Embodiment 1, the shape memory material of the present invention and its manufacturing method will be described in detail.

[0013] The shape memory material of the present invention is composed of an ion gel containing a polymer compound having a number average molecular weight of 4.0×10 5 or more and 1.0×10 7 or less, and an ionic liquid. The anion of the ionic liquid is represented by the formula (1), and the mass ratio of the content of the polymer compound to the content of the ionic liquid is 0.45 or more and less than 4.0. The inventors of the present application have found that by satisfying the above specific composition, the ion gel functions as a shape memory material having excellent moldability.

[0014] [Chemical formula]

[0015] Here, n and m are each an integer of 1 or more, and n + m satisfies 3 or more and 10 or less. Hereinafter, each component of the present invention will be described in detail.

[0016] [Polymer compound] The shape memory material of the present invention contains a polymer compound having a number average molecular weight of 4.0×10 5 or more and 1.0×10 7 or less. When the number average molecular weight of the polymer compound is 4.0×10 5When it is less than this value, it does not have the shape retention ability and shape recovery ability and does not function as a shape memory material. When the number average molecular weight of the polymer compound exceeds 1.0×10 7 it becomes insufficient to be handled as a shape memory material.

[0017] The number average molecular weight of the polymer compound is preferably 4.0×10 5 or more and 2.0×10 6 or less. Thereby, it has excellent shape retention ability and shape recovery ability. Note that the number average molecular weight of the polymer compound means the value measured by the method described in the examples.

[0018] The degree of polymerization of the polymer compound is not particularly limited, but is preferably 5000 or more, more preferably 9000 or more, and even more preferably 14000 or more. The upper limit is not particularly limited, but is preferably 100000 or less.

[0019] As the polymer compound, known polymer compounds can be used, but from the viewpoint of obtaining an ion gel, a polymer compound obtained by polymerizing a radically polymerizable compound is preferred.

[0020] Examples of such radically polymerizable compounds include carboxy group-containing compounds such as (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid, and their esters; amide compounds such as (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-hexyl (meth)acrylamide, N-methyl (meth)acrylamide, N-butyl (meth)acrylamide, N-butyl (meth)acrylamide, N-methylol (meth)acrylamide, and N-methylolpropane (meth)acrylamide; cyano (meth)acrylate compounds such as (meth)acrylonitrile; and the like.

[0021] As the polymer compound, from the viewpoint of obtaining a shape memory material having more excellent effects of the present invention, at least one selected from the group consisting of poly(meth)acrylic acid, poly(meth)acrylate, poly(meth)acrylamide, and poly(meth)acrylonitrile is preferable, poly(meth)acrylic acid or poly(meth)acrylate is more preferable, and polymethacrylic acid or polyacrylate is even more preferable.

[0022] The mass ratio of the content of the polymer compound to the content of the ionic liquid is 0.45 or more and less than 4.0. If it is within this range, it has shape retention ability and shape recovery ability and functions as a shape memory material. Preferably, this ratio is 0.70 or more and 3.2 or less. If it is within this range, it has excellent shape retention ability and shape recovery ability.

[0023] In addition, in the present specification, according to the production method described later, a radical polymerizable compound is polymerized to obtain the above polymer compound. Since the conversion rate of the radical polymerizable compound is substantially 100% (exceeding 95%), the ratio of the content of the radical polymerizable compound to the content of the ionic liquid during production is the same as the ratio of the content of the polymer compound to the content of the ionic liquid.

[0024] <Ionic liquid> In this specification, the ionic liquid means a non-volatile salt formed by a combination of a cation and an anion and having a melting point of 25°C or lower under atmospheric pressure.

[0025] The anion of the ionic liquid is represented by the above formula (1), where n and m are each an integer of 1 or more, and n + m satisfies 3 or more and 10 or less. n and m may be the same or different. Within this range, a shape memory material having shape retention ability and shape recovery ability can be provided. When n + m is 2 or less, the shape retention ability is insufficient. When n + m becomes 11 or more, the glass transition temperature becomes very high and the temperature required to exhibit shape memory characteristics becomes high. More preferably, n + m is 4 or more and 8 or less. Thereby, a shape memory material having excellent shape retention ability and shape recovery ability can be provided.

[0026] Such an anion of the ionic liquid is preferably at least one selected from the group consisting of (pentafluoroethanesulfonyl)imide (BETI), (trifluoromethanesulfonyl)(nonafluorobutanesulfonyl)imide (IM 14 ), and bis(nonafluorobutanesulfonyl)imide (NFSI). With these anions, a shape memory material having excellent shape retention ability and shape recovery ability can be provided. Note that n + m of BETI is 4, and n + m of IM 14 is 5, and n + m of NFSI is 8.

[0027] The cation of the ionic liquid is preferably at least one selected from the group consisting of an organic cation and a metal complex cation, preferably contains an organic cation, and preferably consists of an organic cation. In this specification, the organic cation means a cation that does not contain a metal atom and has at least one carbon atom.

[0028] The organic cation is not particularly limited, and examples thereof include onium. More specifically, ammonium ions (e.g., R A 4N + ), iminium ions (e.g., R B 2C=N + R 1 2), sulfonium ions (e.g., R A 3S + ), oxonium ions (e.g., RA 2O + ) phosphonium ion (representative structure: R A 4P + ), and iodonium ion (e.g., R A 2I + ), etc. can be mentioned.

[0029] In addition, in the above formulas, R A represents substituents such as an alkyl group, an aryl group, and a heterocyclic group. R B represents a hydrogen atom or a monovalent substituent. A plurality of R 1 in the molecule, a plurality of R B in the molecule, or R A and R B in the molecule may be bonded to each other to form a ring. Also, two R A in the molecule, or two R B may jointly form a double bond group (e.g., =O, =S, =NR B ).

[0030] The metal complex cation is not particularly limited, and examples include ferrocene-based, cobaltocene-based, ruthenium-based, and solvated ions in which the high Lewis acidity of lithium, sodium, etc. is reduced by coordination with a crown ether, etc.

[0031] Other forms of the cation include ammonium ion, pyrrolidinium ion, pyridinium ion, piperidinium ion, oxazolium ion, oxazolinium ion, imidazolium ion, thiazolium ion, and phosphonium ion, etc.

[0032] Examples of the ammonium ion include cations represented by the following formula.

[0033] [Chemical formula]

[0034] In the formula, R 1Each independently represents a hydrogen atom or a monovalent substituent, and a plurality of Rs 1 may be the same or different from each other. The monovalent substituent of R 1 is not particularly limited, and examples thereof include a substituted or unsubstituted hydrocarbon group having 1 to 15 carbon atoms which may contain a hetero atom.

[0035] Examples of the pyrrolidinium ion include cations represented by the following formulas.

[0036] [Chemical formula]

[0037] In the formula, R 2 each independently represents a hydrogen atom or a monovalent substituent, and a plurality of Rs 2 may be the same or different from each other. The monovalent substituent of R 2 is not particularly limited, and examples thereof include a substituted or unsubstituted hydrocarbon group having 1 to 15 carbon atoms which may contain a hetero atom.

[0038] Examples of the piperidinium ion include cations represented by the following formulas.

[0039] [Chemical formula]

[0040] In the formula, R 3 each independently represents a hydrogen atom or a monovalent substituent, and a plurality of Rs 3 may be the same or different from each other. The monovalent substituent of R 3 is not particularly limited, and examples thereof include a substituted or unsubstituted hydrocarbon group having 1 to 15 carbon atoms which may contain a hetero atom.

[0041] Examples of the pyridinium ion include cations represented by the following formulas.

[0042] [Chemical formula]

[0043] In the formula, R 4 each independently represents a hydrogen atom or a monovalent substituent, and a plurality of R 4 may be the same or different from each other. The monovalent substituent of R 4 is not particularly limited, and examples thereof include a substituted or unsubstituted hydrocarbon group having 1 to 15 carbon atoms which may contain a hetero atom.

[0044] Examples of the phosphonium ion include cations represented by the following formula.

[0045] [Chemical formula]

[0046] In the formula, R 5 each independently represents a hydrogen atom or a monovalent substituent, and a plurality of R 5 may be the same or different from each other. The monovalent substituent of R 5 is not particularly limited, and examples thereof include a substituted or unsubstituted hydrocarbon group having 1 to 15 carbon atoms which may contain a hetero atom.

[0047] Examples of the imidazolium ion include cations represented by the following formula (2).

[0048] [Chemical formula]

[0049] In the formula, R X , R Y , and R Z each independently represents a hydrogen atom or a monovalent substituent. R X , R Y , and R ZThe monovalent substituent is not particularly limited, and examples thereof include substituted or unsubstituted hydrocarbon groups having 1 to 15 carbon atoms which may contain a hetero atom.

[0050] Preferably, R X and R Y are each a substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms, and R Z is hydrogen. Thereby, a shape memory material having excellent shape retention ability and shape recovery ability can be provided. More preferably, the number of carbon atoms of R X is less than the number of carbon atoms of R Y , and R Z is hydrogen. Thereby, a shape memory material having further excellent shape retention ability and shape recovery ability can be provided. Even more preferably, R X is a substituted or unsubstituted hydrocarbon group having 1 carbon atom, R Y is a substituted or unsubstituted hydrocarbon group having 2 to 8 carbon atoms, and R Z is hydrogen. Thereby, a shape memory material having particularly excellent shape retention ability and shape recovery ability can be provided.

[0051] As described above, the shape memory material of the present invention is composed of an ion gel in which a polymer compound is swollen with a predetermined ionic liquid without using a chemical crosslinking agent. As far as the inventors know, there is no shape memory material in which such a polymer compound is not crosslinked. Further, since it is swollen with an ionic liquid which is a nonvolatile solvent, the shape memory material of the present invention is stable even under special environments such as under vacuum, under high pressure, or in water.

[0052] Since the shape memory material of the present invention is composed of an ion gel, it has excellent thermoformability. For example, when heated to 100 ° C, a large deformation of 150% is possible, and the formability is excellent.

[0053] In the ion gel that constitutes the shape memory material of the present invention, polymer compounds are intertwined with each other, achieving a state similar to crosslinking without using a chemical crosslinking agent. Due to such intertwining, it has excellent mechanical properties and can maintain its shape. Furthermore, since no chemical crosslinking agent is used, for example, by applying a high temperature of 100°C or higher and 150°C or lower and a high pressure of 10 MPa or higher and 1000 MPa or lower, the shape memory material of the present invention can be reshaped and has excellent recyclability.

[0054] The shape memory material of the present invention is colorless and transparent and is significant in terms of design. Specifically, the shape memory material of the present invention has a transmittance of 80% or more, more preferably 95% or more, in the wavelength range of the visible region of 400 nm or more and 800 nm or less. Further, if necessary, a colored transparent shape memory material may be obtained by adding a dye or the like.

[0055] Next, a method for manufacturing the shape memory material of the present invention will be described. FIG. 1 is a flowchart showing a method for manufacturing the shape memory material of the present invention.

[0056] The shape memory material of the present invention is obtained by the following steps S110 and S120. By adopting the method of the present invention, the conversion rate (%) of the radically polymerizable compound exceeds 95%, and the shape memory material of the present invention can be efficiently manufactured. Step S110: Prepare a composition containing a radically polymerizable compound, an ionic liquid, and a radical polymerization initiator. Step S120: Polymerize the composition prepared in step S110.

[0057] In step S110, as the ionic liquid, an ionic liquid in which the anion is represented by the above formula (1) is adopted. Further, the composition for polymerization is prepared by mixing so that the ratio of the mass of the radically polymerizable compound to the content of the ionic liquid satisfies 0.45 or more and less than 4.0. Since the radically polymerizable compound and the ionic liquid are as described above, the description thereof is omitted.

[0058] In step S110, the radical polymerization initiator may be a thermal radical polymerization initiator, a photo radical polymerization initiator, or the like.

[0059] Examples of the thermal radical polymerization initiator include peroxides such as t-butyl peroxybenzoate, di-t-butyl peroxide, cumene hydroperoxide, acetyl peroxide, benzoyl peroxide, lauroyl peroxide, and azo compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, and azobiscyclohexanecarbonitrile.

[0060] Examples of the photo radical polymerization initiator include 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, and the like.

[0061] The content of the radical polymerization initiator is not particularly limited. Exemplarily, when the total content of the radically polymerizable compound and the ionic liquid in the composition is 100 parts by mass, it is in the range of 0.001 parts by mass or more and 3 parts by mass or less. Within this range, polymerization can be carried out without impairing the properties of the resulting ion gel. The radical polymerization initiator may be one kind or two or more kinds. When two or more kinds are used, it is preferable that the total content is within the above range.

[0062] The preparation in step S110 may be carried out by mixing the above components. There are no particular restrictions on the mixing method and order. For example, a method of mixing the radically polymerizable compound and the radical polymerization initiator and then mixing the ionic liquid can be mentioned.

[0063] In step S120, the number average molecular weight is 4.0×10 5 or more and 1.0×10 7A radical polymerizable compound may be polymerized until a polymer compound as described below is produced. For example, such polymerization conditions vary depending on the type of radical polymerization initiator. When the composition contains a thermal radical polymerization initiator, it may be heated in an inert gas atmosphere within a temperature range of 20°C or higher and 130°C or lower for a period of 1 hour or longer and 72 hours or shorter. For example, when the composition contains a photo radical polymerization initiator, deep ultraviolet to ultraviolet rays (wavelength: 280 nm or longer and 405 nm or shorter) may be irradiated.

[0064] Figure 2 is a schematic diagram showing the shape memory and recovery of the shape memory material of the present invention.

[0065] The molded body 200 is made of the shape memory material of the present invention, and the state of shape memory and recovery thereof will be described. The molded body 200 may be in the shape formed during the production of the ion gel (plate-like in FIG. 2). The molded body 200 is composed of a shape memory material made of an ion gel containing a polymer compound 210 and an ionic liquid 220 as described above. The polymer compound 210 has entanglements 230 that are intertwined with each other without using a chemical crosslinking agent.

[0066] By heating the molded body 200 to a predetermined temperature (Tswich) or higher, the molded body 200 becomes deformable and is shaped into a desired shape. Here, the molded body 200 becomes a shaped body 240 shaped horizontally by the collapse of the entanglements 230. By cooling the shaped body 240 to a temperature below the predetermined temperature (Tswich), the ion gel becomes a glassy state, and the shape of the shaped body 240 is memorized.

[0067] By heating the shaped body 240 again to a predetermined temperature (Tswich) or higher, the collapsed entanglements 230 become spherical, the shaped body 240 recovers to the shape of the molded body 200, and by cooling this to a temperature below the predetermined temperature (Tswich), it is fixed in the shape of the molded body 200.

[0068] Here, the predetermined temperature (Tswich) may be the glass transition point (Tg) of the shape memory material. Since the glass transition point of the shape memory material of the present invention is in the range of 35°C or higher and 100°C or lower, the shape memory material of the present invention can store its shape at room temperature (10°C to 30°C).

[0069] For example, when the molded body 200 made of a shape memory material with Tg in the above range is a dining utensil such as a spoon, immersing it in hot water (for example, about 60°C to 100°C) makes it deformable. Shaping the dining utensil according to the state of the hand and then cooling it with water fixes the shape. In this way, a dining utensil shaped according to an individual is obtained. Since the shape memory material of the present invention allows for large deformations exceeding 100%, it can be shaped according to the user's desires.

[0070] In formula (1), an ion gel using an anion in which some or all of the fluorine (F) is replaced with another halogen element X (such as chlorine (Cl), bromine (Br), iodine (I), etc.) can also function as a shape memory material. For example, instead of formula (1), an ion gel represented by formula (3) may be employed. In formula (3), X is a halogen element selected from at least one of the group consisting of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I), and the rest is the same as in formula (1). Such modifications are also within the scope of the present invention.

[0071] [Chemical formula]

[0072] (Embodiment 2) In Embodiment 2, the uses of the shape memory material of the present invention described in Embodiment 1 will be described.

[0073] Figure 3 is a schematic diagram showing an article to which the shape memory material of the present invention is applied.

[0074] A schematic diagram showing the application of the shape memory material of the present invention to articles such as a spoon 300 and a toothbrush 310 is shown. The spoon 300 includes a gripping portion 320 and an operating portion 330 having a recess attached to the gripping portion 320. The toothbrush 310 includes a gripping portion 320 and an operating portion 330 having a brush attached to the gripping portion 320. The gripping portion 320 is made of the shape memory material of the present invention described in Embodiment 1.

[0075] As described with reference to FIG. 2, if the shape memory material of the present invention is adopted for the gripping portion 320, spoons 300 and toothbrushes 310 that can be shaped according to the state of the user's hand can be provided. Note that there is no particular limitation as long as the article has a gripping portion, and it is applicable to daily necessities such as forks and scissors.

[0076] FIG. 4 is a schematic diagram showing another article to which the shape memory material of the present invention is applied.

[0077] A schematic diagram showing the application of the shape memory material of the present invention to an article, a thrombus removal device 400, is shown. The thrombus removal device 400 includes a support portion 410 provided with a heating device and an operating portion 420 for removing a thrombus. The operating portion 420 is made of the shape memory material of the present invention described in Embodiment 1.

[0078] As shown in the upper part of FIG. 4, the thrombus removal device 400 having the operating portion 420 shaped linearly is inserted into the blood vessel 430 and penetrates the thrombus 440. Next, as shown in the lower part of FIG. 4, the operating portion 420 is heated (T>Tg) by the heating device of the support portion 410 and recovers in a spiral shape. Then, by pulling out the thrombus removal device 400 from the blood vessel 430, the thrombus 440 is physically fixed by the operating portion 420 that has recovered in a spiral shape and removed from the blood vessel 430.

[0079] FIG. 5 is a schematic diagram showing yet another article to which the shape memory material of the present invention is applied.

[0080] A schematic diagram showing the application of the shape memory material of the present invention as an article to an artificial muscle 500 is shown. The artificial muscle 500 includes an elastic tube 510 made of an elastic body such as rubber, and a sleeve 520 covering the elastic tube 510. The sleeve 520 is made of the shape memory material of the present invention described in Embodiment 1.

[0081] The sleeve 520 is heated (T>Tg) by a heating means (not shown) such as a heater, and compressed air is introduced into the elastic tube 510 covered with the sleeve 520 in a state where the elastic modulus of the sleeve 520 has decreased. Thereby, the sleeve 520 expands in the radial direction and obtains a force to contract in the length (or axis) direction (conventional McKibben type artificial muscle). In order to maintain this contraction force, it is necessary to maintain a high internal pressure state by supplying compressed air. However, after any contraction (force), the sleeve 520 is cooled (T<Tg) by a cooling means (not shown) such as a refrigerant, and the shape memory material becomes a glassy state and its shape is fixed. As a result, the contraction force can be maintained even after exhausting (internal pressure reduction). When the sleeve 520 is heated again (T>Tg) in the exhausted (internal pressure reduced) state, it returns to its original length and thus functions as a pneumatic artificial muscle.

[0082] The shape memory material of the present invention is not limited to the articles of FIGS. 3 to 5, and is applied to various articles that make use of shape memory, such as daily necessities such as spoons, toothbrushes, scissors, medical products such as indwelling needles and thrombus removal instruments, and devices such as artificial muscles.

[0083] Next, the present invention will be described in detail using specific examples, but it should be noted that the present invention is not limited to these examples.

Example

[0084] [Radical polymerizable compound] Seven types of radical polymerizable compounds were prepared as follows. · Methyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd., M0087, MMA) · Ethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd., M0084, EMA) These were passed through a short column of activated alumina to remove the polymerization inhibitor hydroquinone, purified, and then used. Their structural formulas are shown below.

[0085] [Chemical formula]

[0086] [Ionic liquid] Five types of ionic liquids were prepared as follows. · [C2mim][NFSI]; 1-Ethyl-3-methylimidazolium bis(nonafluorobutanesulfonyl)imide · [C2mim][TFSI]; 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide · [C2mim][BETI]; 1-Ethyl-3-methylimidazolium (pentafluoroethanesulfonyl)imide · [C2mim][IM 14 ; 1-Ethyl-3-methylimidazolium (trifluoromethanesulfonyl)(nonafluorobutanesulfonyl)imide · [C8mim][NFSI]; 1-Octyl-3-methylimidazolium bis(nonafluorobutanesulfonyl)imide Their structural formulas are shown below.

[0087] [Chemical formula]

[0088] [Synthesis of [C2mim][NFSI]] Potassium bis(nonafluorobutanesulfonyl)imide (manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd., EF-N442) and 1-ethyl-3-methylimidazolium bromide (manufactured by Tokyo Chemical Industry Co., Ltd., E0543) were mixed in ethanol at a molar ratio of 1.2:1.0 and stirred for one day.

[0089] Next, ethanol was removed with an evaporator, water was added, and the liquid separation operation was repeated 5 times. The obtained hydrophobic liquid was dried overnight at 120 °C under vacuum to obtain the target ionic liquid.

[0090] <Synthesis of [C2mim][TFSI]> [C2mim][TFSI] was obtained in the same manner as [C2mim][NFSI], except that lithium bis(trifluoromethanesulfonyl)imide (manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd., EF-N115) was used instead of potassium bis(nonafluorobutanesulfonyl)imide.

[0091] <Synthesis of [C2mim][BETI]> [C2mim][BETI] was obtained in the same manner as [C2mim][NFSI], except that lithium bis(pentafluoroethanesulfonyl)imide (manufactured by Kanto Chemical Co., Inc., 49520-27) was used instead of potassium bis(nonafluorobutanesulfonyl)imide.

[0092] <Synthesis of [C2mim][IM 14 > [C2mim][IM 14 was obtained in the same manner as [C2mim][NFSI], except that lithium (trifluoromethanesulfonyl)(nonafluorobutanesulfonyl)imide (manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd., EF-N145) was used instead of potassium bis(nonafluorobutanesulfonyl)imide.

[0093] <Synthesis of [C8mim][NFSI]> [C8mim][NFSI] was obtained in the same manner as [C2mim][NFSI], except that 1-octyl-3-methylimidazolium bromide (manufactured by Tokyo Chemical Industry Co., Ltd., M1904) was used instead of 1-ethyl-3-methylimidazolium bromide.

[0094] [Example 1] In Example 1, an ion gel containing PMMA and [C2mim][NFSI] was synthesized according to the method shown in FIG. 1.

[0095] According to Table 1, 45 parts by mass of MMA as a radical polymerizable compound, 0.022 parts by mass of 2,2’-azobis(2,4-dimethylvaleronitrile) (V65) as a radical polymerization initiator, and 55 parts by mass of [C2mim][NFSI] as an ionic liquid were mixed in a 6 mL vial to prepare a polymerization composition (step S110 in FIG. 1). The polymerization composition was a colorless, transparent, and homogeneous solution.

[0096] In this polymerization composition, the radical polymerizable compound was polymerized to produce an ion gel (step S120 in FIG. 1). Specifically, the vial was sealed with a silicone double cap and bubbled with argon for 15 minutes using a syringe needle. The polymerization composition was poured into a sheet mold in a glove box under an argon atmosphere (oxygen concentration <1 ppm) and heated in an oven at 70°C for 24 hours. The obtained ion gel was designated as the ion gel of Example 1.

[0097] In the ion gel of Example 1, the conversion rate (%) of the radical polymerizable compound was measured as follows. First, the ion gel was completely dissolved in chloroform-d (manufactured by ACROS ORGANICS, 46402-0075) to obtain a solution. Next, the obtained solution was introduced into an NMR sample tube, and NMR measurement (JEOL, ECZ 400S) was performed at 25°C. From the obtained NMR spectrum, the ratio of the number of residual monomers (radical polymerizable compounds) in the ion gel to the number of MMA units of the polymer was calculated, and the conversion rate was calculated by the following formula. Conversion rate (%) = {(units of radical polymerizable compound in polymer) / (units of radical polymerizable compound in polymer + monomer)} × 100

[0098] The number average molecular weight of the ion gel of Example 1 was measured using gel permeation chromatography (GPC). The sample for measurement was prepared as follows.

[0099] The ion gel of Example 1 was purified by reprecipitation. Specifically, the ion gel of Example 1 was dissolved in acetone to a concentration of 1% by mass. Next, the solution was dropped into a large amount of methanol (20 times by volume ratio) to precipitate the polymer (high molecular compound). Polymer powder was obtained by suction filtration.

[0100] The resulting polymer powder was dissolved in acetone again, precipitated, and filtered in the same procedure, and then vacuum-dried at 60 °C for 24 hours. Next, the polymer powder was dissolved in an eluent (10 mM LiBr / DMF) to a concentration of 0.1% by mass, and passed through a 0.45 μm syringe filter to obtain a measurement sample.

[0101] The apparatus, standard sample, and measurement conditions used for the measurement were as follows. Measurement apparatus · Degasser / JASCO (DG-2080-53) · Pump / JASCO (PU-2080) · Interface box / JASCO (LC-Net II / ADC) · Column oven / JASCO (CO-4060) · RI detector / JASCO (RI-4030) · Column / Two Shodex (registered trademark) SB-806M HQ columns connected in series · Guard column / Shodex (registered trademark) SB-G 6B

[0102] Standard sample · Type: Polymethyl methacrylate (PMMA) · Manufacturer: Shodex (registered trademark) · Product: STANDARD M-75 · Molecular weight range: 2,870 - 965,000 (7 points)

[0103] Measurement conditions · Column temperature: 40 °C · Flow rate: 1 mL / min · Eluent: 10 mM LiBr / DMF · Detection: RI These conversion rates, number average molecular weights, and degrees of polymerization are shown in Table 2.

[0104] The shape memory properties of the ion gel of Example 1 were measured using a dynamic mechanical analyzer (Discovery DMA 850, manufactured by TA Instruments, equipped with a liquid nitrogen cooling device (GCA)). A strip-shaped plate (length 20 - 25 mm, width 5 - 6 mm) was cut out from the ion gel of Example 1 and used as a sample for measurement.

[0105] The measurement sample was set in the dynamic mechanical analyzer, heated from room temperature to 60 °C, and equilibrated for 5 minutes. At this time, the clamp length of the measurement sample was 5 mm. At 60 °C, a 100% strain (ε m ) was applied to the measurement sample (original shape) at a tensile rate of 100% / min. While maintaining a 100% strain on the sample, it was cooled from 60 °C to 0 °C at a cooling rate of 5 °C / min and shaped (shape memory). After equilibrating the sample at 0 °C for 5 minutes, the stress was set to 0.0 Pa, and the temperature was raised from 0 °C to 100 °C at a heating rate of 3.0 °C / min. At this time, the strain (ε u (T)) was measured every 10 °C from 0 °C to 100 °C.

[0106] The shape fixation rate Rf at 0 °C and the shape recovery rate Rr at each temperature were calculated from the following equations. Rf = ε u (0) / ε m ×100 Rr = (ε m - ε u (T)) / ε m ×100

[0107] The shape retention ability at room temperature was evaluated by the shape recovery rate Rr at 20 °C. When Rr was 5% or less, it was rated as ○ (good); when Rr was more than 5% and 10% or less, it was rated as △ (fair); when Rf was more than 10%, it was rated as × (poor).

[0108] The shape restoration ability at high temperature was evaluated by the shape recovery rate Rr at 100 °C. When Rf was more than 80%, it was rated as ○ (good); when Rr was more than 60% and 80% or less, it was rated as △ (fair); when Rf was 60% or less, it was rated as × (poor). The results are shown in Table 3.

[0109] Regarding the shape memory properties of the ion gel of Example 1, a cycle test was conducted using a tensile testing machine (manufactured by Shimadzu Corporation, AGS-X). A sheet in the shape of a tensile No. 7 dumbbell (conforming to JIS K 6251) was cut out from the ion gel of Example 1 and used as a measurement sample. The sample was set in the tensile testing machine, a strain of 150% was applied, and then the strain was removed. Next, after standing in an oven at 100 °C for 5 minutes, it was left standing at room temperature for 10 minutes, and again, the strain was applied up to 150%, and then the strain was removed. This was performed for 5 cycles. The results are shown in FIGS. 6 and 7.

[0110] The transmittance of the ion gel of Example 1 was measured using an ultraviolet-visible-near-infrared spectrophotometer (manufactured by Shimadzu Corporation, UV-2600). The results are shown in FIG. 8.

[0111] [Examples 2 to 13] Examples 2 to 13 were synthesized in the same manner as Example 1 using the radical polymerizable compounds and ionic liquids shown in Table 1 to obtain ion gels containing various polymer compounds and ionic liquids. The obtained ion gels are referred to as the ion gels of Examples 2 to 13. Similar to Example 1, the conversion rate, number average molecular weight, degree of polymerization, and shape memory properties of the ion gels of Examples 2 to 13 were investigated. The results are shown in Tables 2 and 3.

[0112] The above results will be collectively explained.

[0113]

Table 1

[0114]

Table 2

[0115] According to Tables 1 and 2, in Examples 1 to 13, the conversion rate of the radical polymerizable compound exceeded 95% in all cases. From this, since substantially all of the radical polymerizable compounds used as raw materials became the target polymers, the content of the polymer compounds in the ion gels of Examples 1 to 13 may be regarded as the content of the polymerizable compounds in the raw materials.

[0116] According to Tables 1 and 2, the ion gels of Examples 1 to 9 are composed of an ion gel containing a polymer compound having a number average molecular weight of 4.0×10 5 or more and 1.0×10 7 or less, and an ionic liquid. The anion of the ionic liquid is represented by the above formula (1), and it was found that the mass-based ratio of the content of the polymer compound to the content of the ionic liquid satisfies 0.45 or more and less than 4.0.

[0117] On the other hand, the ion gel of Example 10 does not satisfy the anion of the above formula (1). The ion gel of Example 11 does not satisfy the number average molecular weight of the above formula (1). The ion gels of Examples 12 and 13 do not satisfy the mass-based ratio of the above formula (1).

[0118] FIG. 6 is a diagram showing the state of the ion gel of Example 1 in the cycle test. FIG. 7 is a diagram showing the stress-strain curve of the ion gel of Example 1 in the cycle test.

[0119] FIG. 6 shows the state of the test piece of the ion gel of Example 1 before the cycle test (A), after applying a strain of 150% in the first cycle test (B), and after heating and before applying strain in the fifth cycle test (C).

[0120] According to FIG. 6, even after applying a strain of 150% five times, it has returned to the same length as the test piece before applying the strain, indicating that excellent shape memory characteristics are exhibited.

[0121] According to FIG. 7, the stress-strain curves of the ion gel of Example 1 all showed substantially the same curve regardless of the number of cycle tests. From this, it was found that the shape memory characteristics of the ion gel of Example 1 are also well restored after being exhibited in terms of mechanical properties.

[0122]

Table 3

[0123] According to Table 3, it was found that the ionic gels of Examples 1 to 9 are excellent in both the shape retention ability at room temperature and the shape recovery ability above the melting point, and function as a shape memory material that can be used at room temperature. On the other hand, it was found that the ionic gels of Examples 10 to 13 cannot recover their shape even if they can be shape-memorized, or vice versa, and do not function as a shape memory material.

[0124] From this, among ionic gels containing a polymer compound and an ionic liquid, an ionic gel containing a polymer compound having a number average molecular weight of 4.0×10 5 or more and 1.0×10 7 or less, and an ionic liquid, wherein the anion of the ionic liquid is represented by the formula (1), and the mass-based ratio of the content of the polymer compound to the content of the ionic liquid satisfies 0.45 or more and less than 4.0, has been shown to be effective as a shape memory material.

[0125] FIG. 8 is a diagram showing the transmission spectrum of the ionic gel of Example 1.

[0126] According to FIG. 8, the ionic gel of Example 1 exhibits high transmittance of 95% or more in the visible light region. Therefore, it can also be used for applications that require transparency.

Industrial Applicability

[0127] The shape memory material of the present invention is composed of an ionic gel containing a polymer compound and a predetermined ionic liquid, and can retain its shape at room temperature. The shape memory material of the present invention is applied to various articles that make use of shape memory, such as daily necessities such as spoons, toothbrushes, and scissors, medical products such as indwelling needles and thrombus removal instruments, and devices such as artificial muscles.

Explanation of Signs

[0128] 200 Molded body 210 Polymer compound 220 Ionic liquid 230 Entanglement 240 Shaping body 300 Spoon 310 Toothbrush 320 Holding part 330, 420 Acting part 400 Thrombus removal device 410 Support part 430 Blood vessel 440 Thrombus 500 Artificial muscle 510 Elastic tube 520 Sleeve

Claims

1. The ion gel is composed of a polymer compound having a number average molecular weight of 4.0 × 10 ５ or more and 1.0 × 10 ７ or less, and an ionic liquid The anion of the ionic liquid is represented by the formula (1), The shape memory material in which the ratio of the content of the polymer compound to the content of the ionic liquid based on mass is 0.45 or more and less than 4.

0. 【Chemical 1】 Here, n and m are each an integer of 1 or more, and n + m satisfies 3 or more and 10 or less.

2. The shape memory material according to claim 1, wherein n and m each satisfy 4 or more and 8 or less.

3. The shape memory material according to claim 1 or 2, wherein the ratio is 0.70 or more and 3.2 or less.

4. The shape memory material according to any one of claims 1 to 3, wherein the polymer compound is at least one compound selected from the group consisting of poly(meth)acrylic acid, poly(meth)acrylate, poly(meth)acrylamide, and poly(meth)acrylonitrile.

5. The shape memory material according to claim 4, wherein the polymer compound is poly(meth)acrylic acid or poly(meth)acrylate.

6. The shape memory material according to claim 5, wherein the polymer compound is polymethacrylic acid or polyacrylate.

7. The cation of the ionic liquid is at least one cation selected from the group consisting of ammonium ion, pyrrolidinium ion, pyridinium ion, piperidinium ion, oxazolium ion, oxazolinium ion, imidazolium ion, thiazolium ion, and phosphonium ion. The shape memory material according to any one of claims 1 to 6.

8. The shape memory material according to claim 7, wherein the cation is an imidazolium ion.

9. The shape memory material according to claim 8, wherein the imidazolium ion is represented by the formula (2). [Chemical Formula 2] Here, R Ｘ , R Ｙ and R Ｚ each represents hydrogen or a monovalent substituent.

10. Said R Ｘ and said R Ｙ are each a substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms, and said R Ｚ is hydrogen. The shape memory material according to claim 9.

11. The anion of the ionic liquid is at least one selected from the group consisting of (pentafluoroethanesulfonyl)imide (BETI), (trifluoromethanesulfonyl)(nonafluorobutanesulfonyl)imide (IM １４ ), and bis(nonafluorobutanesulfonyl)imide (NFSI), the shape memory material according to any one of claims 1 to 10.

12. The shape memory material according to any one of claims 1 to 11, having a transmittance of 80% or more in the wavelength range of 400 nm or more and 800 nm or less.

13. Mixing a radically polymerizable compound, a radical polymerization initiator, and an ionic liquid whose anion is represented by the formula (1) so that the ratio of the radically polymerizable compound to the content of the ionic liquid based on mass satisfies 0.45 or more and less than 4.0, and preparing a polymerization composition. Polymerize the radically polymerizable compound in the polymerization composition to produce a polymer compound having a number average molecular weight of 4.0×10 ５ or more and 1.0×10 ７ or less, and produce an ion gel containing the polymer compound and the ionic liquid The method for producing a shape memory material according to any one of claims 1 to 12, comprising: 【Chemical Formula 3】 Here, n and m are each an integer of 1 or more, and n + m satisfies 3 or more and 10 or less.

14. An article comprising the shape memory material according to any one of Claims 1 to 12.

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