Small molecule ionic liquid monomer adhesive and preparation method thereof

Abstract

The invention discloses a micromolecular ionic liquid monomer adhesive and a preparation method thereof, and belongs to the technical field of adhesives. The structural formula of the micromolecular ionic liquid monomer adhesive is shown as follows: # imgabs0 #. The preparation method adopted by the invention comprises the following steps: reacting a halogenated silane reagent with imidazole containing a functional group alkyl side chain to obtain a micromolecular ionic liquid monomer consisting of imidazole cations containing a functional group alkane side chain and a silane side chain and halogen anions; and carrying out anion exchange reaction on the micromolecule ionic liquid monomer and salt containing target anions to obtain the micromolecule ionic liquid monomer adhesive. The small molecule ionic liquid is synthesized through a two-step method, the synthesis steps of the ionic liquid adhesive are simplified, the glass transition temperature of the ionic liquid adhesive is reduced, and the wettability of the ionic liquid adhesive on a substrate material is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives, and in particular relates to a small molecule ionic liquid monomer adhesive and a preparation method thereof. Background Art

[0002] In recent years, ionic liquids have become a research hotspot in the field of adhesives due to their excellent thermal stability, low flammability, wide electrochemical window, and excellent processability, and are considered to be a very promising adhesive material.

[0003] Ionic liquids are composed of anions and cations. By matching different anion and cation types or changing the substituents on the cations, ionic liquids with different viscosities can be obtained to meet the application requirements of different scenarios. The polyionic liquid obtained by polymerizing the ionic liquid monomer has a high cohesive force, thus showing excellent bonding performance. Polyionic liquids inherit the excellent structural and electrical properties of ionic liquids, such as designability and high conductivity, and take into account the original properties of polymers such as mechanical durability and processability (patent 201911140763.5). Highly conductive polyionic liquid adhesives can also be obtained by adding metal salts (patent 202311201214.0). However, the viscosity of polyionic liquids is high, and they are limited by material and energy transfer during use. In addition, since the degree of polymerization of the polymerization reaction is difficult to accurately control, the stability of the bonding performance of polyionic liquids is low, which is not conducive to the engineering application of polyionic liquids. Reducing the degree of polymerization of ionic liquids or directly using ionic liquid monomers as adhesives can avoid a series of problems caused by polymerization reactions, while simplifying the synthesis steps, reducing costs, and improving production efficiency. Therefore, the development and research of small molecule ionic liquid monomers as adhesives is of great significance for promoting the development and application of ionic liquids in the field of adhesives. Summary of the invention

[0004] In view of the problems of complex synthesis process, high viscosity and poor wettability to substrate materials of polyionic liquids, the present invention proposes a small molecule ionic liquid monomer adhesive and a preparation method thereof. The present invention synthesizes the small molecule ionic liquid by a two-step method, simplifies the synthesis steps of the ionic liquid adhesive, presents a liquid state at room temperature, reduces the glass transition temperature of the ionic liquid adhesive, and improves the wettability of the ionic liquid adhesive on the substrate material.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the purposes of the present invention is to provide a small molecule ionic liquid monomer adhesive, the structural formula of which is as follows:

[0007]

[0008] R1 is an alkane side chain or an alkene side chain containing a functional group; the functional group is selected from any one of an amino group, a carboxyl group, a hydroxyl group and a cyano group;

[0009] R2 is selected from any one of —OCH2CH3, —OCH3, —OCH(CH3)2, —OSi(CH3)3 and —COCH2CH3;

[0010] X - It is an anion;

[0011] The value of n is an integer between 1 and 5.

[0012] Furthermore, the functional group-containing alkane side chain is selected from -CH2CH2NH2, -CH2CH2COOH, -CH2COOH, -CH2CH2OH, -CH=CH2, -CH2C≡N, Any of the following:

[0013] The anion is selected from NO 3- 、SO4 2- 、ClO4 - 、(CF3SO2)2N - 、OTF - 、BF4 - PF6 - 、FSI - and TFSI - Any one of .

[0014] The second object of the present invention is to provide a method for preparing a small molecule ionic liquid monomer adhesive, comprising the following steps:

[0015] The halogenated silane reagent is reacted with imidazole containing a functional group alkyl side chain to obtain a small molecule ionic liquid monomer composed of an imidazole cation containing a functional group alkane side chain and a silane side chain and a halogen anion;

[0016] The small molecule ionic liquid monomer undergoes anion exchange reaction with a salt containing a target anion to obtain a small molecule ionic liquid monomer adhesive.

[0017] Further, the halosilane reagent is selected from one or more of chlorotriethoxysilane, (3-chloropropyl)trimethoxysilane, (3-bromopropyl)trimethoxysilane, (3-iodopropyl)trimethoxysilane, 3-chloropropyltriethoxysilane, (chloromethyl)trimethoxysilane, (chloromethyl)triethoxysilane, chloromethyltriisopropoxysilane, (3-chloropropyl)tris(trimethylsiloxy)silane and trimethoxychlorosilane.

[0018] Furthermore, the imidazole containing a functional group alkyl side chain is selected from one or more of 1-(2-hydroxyethyl)imidazole, 1-imidazoleacetic acid, 3-imidazole-1-yl-propionic acid, (1-imidazole)acetonitrile, 2-(1-imidazole)ethylamine dihydrochloride, 1-(4-cyanophenyl)imidazole, 1-vinylimidazole and 4-(1-imidazole)benzoic acid.

[0019] Furthermore, the salt containing the target anion is selected from one or more of lithium nitrate, lithium sulfate, lithium perchlorate, trifluoromethylsulfonyl lithium, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethane)sulfonyl imide.

[0020] Furthermore, the specific steps of the reaction include: carrying out the reaction in an organic solvent under the protection of an inert atmosphere, the reaction temperature is 70-120° C., and the reaction time is 12-72 hours.

[0021] Furthermore, the organic solvent is selected from one or more of anhydrous ethanol, methanol, acetonitrile, ethyl acetate, dimethyl sulfoxide, toluene, acetone, dichloromethane, chloroform, NN-dimethylformamide and tetrahydrofuran.

[0022] Furthermore, the specific steps of the anion exchange reaction include: dissolving the small molecule ionic liquid monomer and the salt containing the target anion in a solvent respectively and mixing them to complete the anion exchange reaction.

[0023] Furthermore, the solvent is selected from one or more of deionized water, acetone and tetrahydrofuran.

[0024] Compared with the prior art, the present invention has the following advantages and technical effects:

[0025] (1) The small molecule ionic liquid monomer imidazolium cation structure designed and synthesized by the present invention contains silane side chains of silicon oxygen groups and alkane side chains of specific functional groups, and the cation structure can be modified in a variety of ways to meet specific application requirements;

[0026] (2) Compared with the prior art, the small molecule ionic liquid monomer adhesive designed and synthesized by the present invention has a lower glass transition temperature, is in a liquid or paste state at room temperature, has good wettability for bonding substrate materials, and gradually solidifies under high temperature conditions, thereby showing good bonding performance;

[0027] (3) The preparation method of the small molecule ionic liquid monomer adhesive designed and synthesized by the present invention is simple, easy to operate, green and safe, and only two steps are required to obtain the target small molecule ionic liquid monomer, which is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 After the bonding experiment of IL-1 prepared in Example 1 of the present invention on aluminum, ceramic, epoxy resin, copper, and stainless steel substrates, the shear strength data of the bonding point was measured at room temperature;

[0030] Figure 2 The results of the adhesion test of IL-1 prepared in Example 1 of the present invention on aluminum, copper and stainless steel substrates after being immersed in water for 24 hours are shown;

[0031] Figure 3 This is a diagram showing the bonding effect of IL-1 prepared in Example 1 of the present invention and the energetic hydrogel on a stainless steel substrate. DETAILED DESCRIPTION

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0034] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0035] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0036] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0037] The embodiment of the present invention provides a small molecule ionic liquid monomer adhesive, the structural formula of which is as follows:

[0038]

[0039] R1 is an alkane side chain or an alkene side chain containing a functional group; the functional group is selected from amino, carboxyl, hydroxyl or cyano;

[0040] R2 is selected from any one of —OCH2CH3, —OCH3, —OCH(CH3)2, —OSi(CH3)3 and —COCH2CH3; three R2 and Si atom form a silane-containing side chain;

[0041] X - It is an anion;

[0042] The value of n is an integer between 1 and 5.

[0043] The functional group-containing alkane side chain is selected from -CH2CH2NH2, -CH2CH2COOH, -CH2COOH, -CH2CH2OH, -CH=CH2, -CH2C≡N, Any of the following:

[0044] The anion is selected from NO 3- 、SO4 2- 、ClO4 - 、(CF3SO2)2N - 、OTF - 、BF4 - PF6 - 、FSI - and TFSI - Any one of .

[0045] The present invention also provides a method for preparing a small molecule ionic liquid monomer adhesive, comprising the following steps:

[0046] (1) reacting a halogenated silane reagent with an imidazole having an alkyl side chain having a functional group to obtain a small molecule ionic liquid monomer composed of an imidazole cation having an alkane side chain having a functional group and a silane side chain and a halogen anion;

[0047] (2) The small molecule ionic liquid monomer undergoes anion exchange reaction with a salt containing a target anion to obtain a small molecule ionic liquid monomer adhesive.

[0048] In some embodiments, the halogenated silane reagent is one or more of chlorotriethoxysilane, (3-chloropropyl) trimethoxysilane, (3-bromopropyl) trimethoxysilane, (3-iodopropyl) trimethoxysilane, 3-chloropropyl triethoxysilane, (chloromethyl) trimethoxysilane, (chloromethyl) triethoxysilane, chloromethyl triisopropoxysilane, (3-chloropropyl) tris(trimethylsiloxy) silane and trimethoxychlorosilane. As a typical but non-limiting example, in the following preferred embodiments of the present invention, the halogenated silane reagent can be selected from (3-chloropropyl) trimethoxysilane.

[0049] In some embodiments, the imidazole containing the functional group alkyl side chain is one or more of 1-(2-hydroxyethyl)imidazole, 1-imidazoleacetic acid, 3-imidazole-1-yl-propionic acid, (1-imidazole)acetonitrile, 2-(1-imidazole)ethylamine dihydrochloride 1-(4-cyanophenyl)imidazole, 1-vinylimidazole and 4-(1-imidazole)benzoic acid. As a typical but non-limiting example, in the following preferred embodiments of the present invention, the imidazole containing the functional group alkyl side chain can be selected from 1-imidazoleacetic acid, 1-vinylimidazole, 1-(2-hydroxyethyl)imidazole or (1-imidazole)acetonitrile.

[0050] In some embodiments, the salt containing the target anion is one or more of lithium nitrate, lithium sulfate, lithium perchlorate, trifluoromethylsulfonyl lithium, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethane)sulfonyl imide. As a typical but non-limiting example, in the following preferred embodiments of the present invention, the salt containing the target anion can be selected from lithium bis(trifluoromethane)sulfonyl imide.

[0051] In some embodiments, the specific steps of the reaction include: reacting in a solvent under the protection of an inert atmosphere, the reaction temperature is 70-120°C, and the reaction time is 12-72h. As a typical but non-limiting example, in the following preferred embodiments of the present invention, the reaction temperature can be selected at 90°C, the reaction time can be selected at 48h, and the atmosphere can be selected as a nitrogen atmosphere. The solvent is one or more of anhydrous ethanol, methanol, acetonitrile, ethyl acetate, dimethyl sulfoxide, toluene, acetone, dichloromethane, chloroform, NN-dimethylformamide and tetrahydrofuran. As a typical but non-limiting example, in the following preferred embodiments of the present invention, the solvent can be selected as dimethyl sulfoxide.

[0052] In some embodiments, the specific steps of the anion exchange reaction include: dissolving the small molecule ionic liquid monomer and the salt containing the target anion in a solvent and mixing them respectively to complete the anion exchange reaction. The conditions of the anion exchange reaction are: the reaction temperature is 30°C and the reaction time is 24h. The solvent for dissolving the small molecule ionic liquid monomer and the solvent for dissolving the salt containing the target anion can be the same or different. The solvent is one or more of deionized water, acetone and tetrahydrofuran. As a typical but non-limiting example, in the following preferred embodiments of the present invention, the solvent can be selected from deionized water.

[0053] The "room temperature" in the present invention refers to 20-30°C unless otherwise specified.

[0054] The raw materials used in the present invention are all purchased from the market.

[0055] The technical solution of the present invention is further illustrated by the following embodiments.

[0056] Example 1

[0057] A method for preparing a small molecule ionic liquid monomer adhesive comprises the following steps:

[0058] (1) Weigh 19.87 g of (3-chloropropyl)trimethoxysilane and 12.61 g of 1-imidazoleacetic acid and dissolve them in 50 mL of dimethyl sulfoxide respectively. Add the former dropwise to the latter using a dropping funnel under stirring, and protect with nitrogen. Mix, stir, and heat to react at 90° C. for 48 h. After the reaction is completed and cooled, the reaction solution is precipitated with ethyl acetate, unreacted raw materials are removed, and the precipitate is collected. The precipitate is washed with ethyl acetate three times and then dried in vacuum at 50° C. to obtain a small molecule ionic liquid monomer with a yield of 83%, which is named IL-1 precursor.

[0059] (2) Weigh 21.15 g of the above-mentioned small molecule ionic liquid monomer IL-1 and dissolve it in 100 mL of deionized water; weigh 28.71 g of lithium bis(trifluoromethane)sulfonyl imide and dissolve it in 50 mL of deionized water; mix the two parts of the aqueous solution and stir them at 30° C. for 24 h to perform anion exchange reaction; after the reaction is completed, filter the solution to obtain a precipitate; wash the precipitate with deionized water three times; and then dry it in a vacuum drying oven at 40° C. for 72 h to obtain the target small molecule ionic liquid monomer adhesive with a yield of 70%, which is named IL-1.

[0060] Example 2

[0061] The same as Example 1, except that the 1-imidazoleacetic acid in step (1) is replaced by 1-vinylimidazole in an equal molar amount, and the obtained product is named IL-2.

[0062] Example 3

[0063] The same as Example 1, except that the 1-imidazoleacetic acid in step (1) is replaced by 1-(2-hydroxyethyl)imidazole in an equal molar amount, and the obtained product is named IL-3.

[0064] Example 4

[0065] The same as Example 1, except that the 1-imidazoleacetic acid in step (1) is replaced by (1-imidazolyl)acetonitrile in equal moles, and the obtained product is named IL-4.

[0066] Performance Test:

[0067] The bonding performance of the small molecule ionic liquid monomer adhesive obtained in Examples 1-4 above was tested. The substrate materials in the bonding experiments were aluminum, ceramic, epoxy resin, copper, and stainless steel.

[0068] The bonding strength test conditions and methods are as follows: ambient temperature 25°C, lap shear tensile test rate 50mm / min -1 , bonding area is 12*20mm 2 .

[0069] Figure 1 The results of the lap shear test of the interface bonding strength of IL-1 on aluminum, ceramic, epoxy resin, copper, and stainless steel substrates are shown in Figure 1. The experimental results show that with IL-1 as the interface adhesive, the maximum tensile stress of the interface bonding of aluminum, ceramic, epoxy resin, copper, and stainless steel substrates is 356N, 310N, 585N, 67N, and 226N, respectively, among which the epoxy resin material bonding interface has the maximum tensile strength of 2.44MPa.

[0070] Figure 2 The interfacial bonding strength of the metal lap joints bonded to IL-1 after 24 hours of water immersion. The experimental results show that the maximum tensile stress of the bonding interface of the lap joints made of aluminum, copper and stainless steel after water immersion is 283N, 33N and 186N respectively.

[0071] Figure 3 The results of the interface strength test of IL-1 bonding stainless steel and energetic hydrogel material show that the interface bonding strength is 1.8MPa (using the 180° peeling method, the effective interface bonding area is 10*10mm 2 , the maximum tensile strength of the interface should be 180N).

[0072] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A small molecule ionic liquid monomer adhesive, characterized in that: The structural formula is as follows: R1 is an alkane side chain or an alkene side chain containing a functional group; the functional group is selected from any one of an amino group, a carboxyl group, a hydroxyl group and a cyano group; R2 is selected from any one of —OCH2CH3, —OCH3, —OCH(CH3)2, —OSi(CH3)3 and —COCH2CH3; X - It is an anion; The value of n is an integer between 1 and 5.

2. The small molecule ionic liquid monomer adhesive according to claim 1, characterized in that: The functional group-containing alkane side chain is -CH2CH2NH2, -CH2CH2COOH, -CH2COOH, -CH2CH2OH, -CH=CH2, -CH2C≡N, Any of the following: The anion is selected from NO 3- 、SO4 2- 、ClO4 - 、(CF3SO2)2N - 、OTF - 、BF4 - PF6 - 、FSI - and TFSI - Any one of .

3. A method for preparing a small molecule ionic liquid monomer adhesive as claimed in claim 1 or 2, characterized in that: The following steps are involved: The halogenated silane reagent is reacted with imidazole containing a functional group alkyl side chain to obtain a small molecule ionic liquid monomer composed of an imidazole cation containing a functional group alkane side chain and a silane side chain and a halogen anion; The small molecule ionic liquid monomer undergoes anion exchange reaction with a salt containing a target anion to obtain a small molecule ionic liquid monomer adhesive.

4. The method for preparing the small molecule ionic liquid monomer adhesive according to claim 3, characterized in that: The halogenated silane reagent is selected from one or more of chlorotriethoxysilane, (3-chloropropyl)trimethoxysilane, (3-bromopropyl)trimethoxysilane, (3-iodopropyl)trimethoxysilane, 3-chloropropyltriethoxysilane, (chloromethyl)trimethoxysilane, (chloromethyl)triethoxysilane, chloromethyltriisopropoxysilane, (3-chloropropyl)tris(trimethylsiloxy)silane and trimethoxychlorosilane.

5. The method for preparing the small molecule ionic liquid monomer adhesive according to claim 3, characterized in that: The imidazole containing a functional group alkyl side chain is selected from one or more of 1-(2-hydroxyethyl)imidazole, 1-imidazoleacetic acid, 3-imidazole-1-yl-propionic acid, (1-imidazole)acetonitrile, 2-(1-imidazole)ethylamine dihydrochloride, 1-(4-cyanophenyl)imidazole, 1-vinylimidazole and 4-(1-imidazole)benzoic acid.

6. The method for preparing the small molecule ionic liquid monomer adhesive according to claim 3, characterized in that: The salt containing the target anion is selected from one or more of lithium nitrate, lithium sulfate, lithium perchlorate, trifluoromethylsulfonyl lithium, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethane)sulfonyl imide.

7. The method for preparing a small molecule ionic liquid monomer adhesive according to claim 3, characterized in that: The specific steps of the reaction include: carrying out the reaction in an organic solvent under the protection of an inert atmosphere, the reaction temperature being 70-120° C., and the reaction time being 12-72 hours.

8. The method for preparing the small molecule ionic liquid monomer adhesive according to claim 7, characterized in that: The organic solvent is selected from one or more of anhydrous ethanol, methanol, acetonitrile, ethyl acetate, dimethyl sulfoxide, toluene, acetone, dichloromethane, chloroform, NN-dimethylformamide and tetrahydrofuran.

9. The method for preparing a small molecule ionic liquid monomer adhesive according to claim 3, characterized in that: The specific steps of the anion exchange reaction include: dissolving the small molecule ionic liquid monomer and the salt containing the target anion in a solvent respectively and mixing them to complete the anion exchange reaction.

10. The method for preparing a small molecule ionic liquid monomer adhesive according to claim 9, characterized in that: The solvent is selected from one or more of deionized water, acetone and tetrahydrofuran.

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