High-strength and high-toughness ionic gel based on weaving node crosslinking as well as preparation and application of high-strength and high-toughness ionic gel

Abstract

The invention discloses high-strength and high-toughness ionic gel based on weaving node crosslinking, a preparation method thereof and application of the high-strength and high-toughness ionic gel in a flexible electronic material. The preparation method comprises the following steps: in the presence or absence of a catalyst, carrying out copolymerization on polyisocyanate, a polyhydroxy precursor and weaving nodes in a dispersion medium containing an organic solvent and an ionic liquid to form a polymer network, and then removing the organic solvent to obtain the high-strength and high-toughness ionic gel based on weaving node crosslinking, the polyhydroxy precursor comprises an ionic liquid monomer; the weaving node is a three-dimensional crossing structure product formed by a coordination reaction of a ligand and a copper (I) salt, and the ligand is 1, 10-phenanthroline with more than two hydroxyl substituent groups and / or 2, 2 '-dipyridyl with more than two hydroxyl substituent groups.

Description

Technical Field

[0001] The present invention relates to the field of ion gels, and particularly to a high-strength and high-toughness ion gel (WIG) based on woven node crosslinking, its preparation method and application. Background Art

[0002] Ion gels are composed of a polymer network and small molecule ionic liquids, and have good flexibility, conductivity and a wide temperature range of use. Compared with hydrogels, they have low volatility and are flame retardant, thus having a very broad prospect in the field of flexible electronic materials. At present, they have received more and more attention and are accelerating the development of flexible electronic products, and are of great significance in aspects such as human-machine interfaces and intelligent robot sensing, and gel polymer electrolytes in energy storage devices. However, since the polymer network is solvated by small molecule ionic liquids, most ion gels have poor mechanical properties, which greatly hinders their application in high-toughness scenarios (such as bionic ligaments, etc.). High-strength and high-toughness polymer materials have always been necessary to meet practical applications. The acquisition of high toughness helps to extend the service life of materials and provides support for green development.

[0003] In recent years, constructing high-performance ion gel materials has become a hot topic of concern. At present, its construction strategy partly depends on the design of molecular structure, including introducing covalent crosslinking sites, sacrificial bonds, quadruple hydrogen bonds and supramolecular coordination bonds, etc. (Sci. Adv. 2019, 5, e aax0648; Nat. Commun. 2022, 13, 4868; J. Mater. Chem. A 2024, 12, 12134; Angew. Chem. Int. Edit. 2024, 63, e202403220). Among these methods, ion gel materials constructed by covalent polymer networks lack dynamics and have low toughness of ion gel materials; ion gel materials constructed by dynamic bonds and supramolecular interactions always exhibit low mechanical strength. In addition, by constructing rigid microdomains composed of non-solvated polymers or inorganic fillers in ion gels, the tensile stress can be effectively dispersed, thereby improving the strength and fracture toughness of the materials. However, due to the strong binding of the microdomains to the polymer chains, the deformation ability of ion gels is relatively reduced. Ion gels with a crystalline polymer network as the backbone further improve the strength and toughness of the materials, but the obtained materials lose elasticity. Constructing high-strength and high-toughness ion gel elastomers remains a challenge.

[0004] Through the weaving technique, linear materials can be formed into a network in an interwoven manner, enabling them to exhibit ideal strength and elasticity. Applying the above topological structure at the molecular level has the potential to construct high-performance woven materials. Recently, introducing weaving nodes into a polymer network to prepare elastomers, due to their dynamic properties and additional entanglement effects, the elastomers exhibit higher toughness than covalent polymer networks. Therefore, using weaving nodes to prepare polymer networks helps to prepare ion gel elastomer materials with both high strength and high toughness, providing support for the development of the flexible electronic materials industry. Summary of the Invention

[0005] Constructing a polymer network through weaving nodes can obtain high-performance polymer materials. This is because the material simultaneously possesses dynamicity and structural stability. Under the action of an external force, the weak interactions formed by coordination bonds endow the polymer network with dynamicity, enabling its crosslinking points to slide to prevent network damage and achieving the effect of dispersing stress; on the other hand, due to the woven interlocking structure formed by weaving, the polymer network can still maintain the integrity of its structure. Therefore, using the woven polymer network as the framework of the ion gel material can achieve the construction of an ion gel material with both high strength and high toughness.

[0006] A weaving node is a spiral-shaped molecule with a cross structure. For example, it can be formed by coordinating a 1,10-phenanthroline-based ligand with a copper(I) salt. Introducing hydroxymethyl functional groups at the 2,9 positions of the 1,10-phenanthroline-based ligand can serve as a crosslinking agent for the polyurethane network. Since the weaving node ligand and the copper(I) salt are combined in a coordination bond manner, it endows its dynamic characteristics under a stressed state. On the other hand, the cross structure formed by coordinating the 1,10-phenanthroline-based ligand with the copper(I) salt endows the polymer network with the characteristics of woven interlocking (structural stability), thus maintaining the high strength of the material.

[0007] Aiming at the technical problems introduced in the background art and the deficiencies existing in the art, based on the unique advantages of the woven structure, the present invention provides a preparation method for an ion gel material with both high strength and high toughness. Using polyisocyanates, polyhydroxy monomers, oligomers, etc. as the polymerization reaction precursors, and using weaving nodes constructed with 1,10-phenanthroline and other building blocks as crosslinking agents, a three-dimensional polyurethane network is formed through the addition polymerization reaction of hydroxyl functional groups and isocyanate groups. During the polymerization process, small molecule ionic liquids are used as the dispersion medium, thereby forming a polyurethane ion gel material. The polyurethane ion gel has the dynamicity and structural stability of the woven interlocking structure, and thus can have both high strength and high toughness, endowing the ion gel material with a wider application range.

[0008] [1]A preparation method of a high-strength and high-toughness ionic gel based on woven node crosslinking, comprising: copolymerizing a polyisocyanate, a polyhydroxy precursor, and a woven node in a dispersion medium containing an organic solvent and an ionic liquid with or without the presence of a catalyst to form a polymer network, and then removing the organic solvent to obtain the high-strength and high-toughness ionic gel based on woven node crosslinking.

[0009] In some preferred embodiments, the copolymerization of the preparation method of the high-strength and high-toughness ionic gel based on woven node crosslinking is carried out in the presence of a catalyst. The catalyst may include organotin catalysts, etc. Further, the organotin catalyst may include dibutyltin dilaurate, etc. In the present invention, the dosage of the catalyst does not need to be particularly required and can be added according to the conventional dosage in the art.

[0010] The organic solvent may include N,N-dimethylformamide (DMF), etc.

[0011] The dosage of the organic solvent may be 1 to 5 times the total mass of the polyisocyanate, the polyhydroxy precursor, the woven node, and the ionic liquid. To ensure the polymerization reaction efficiency, it is preferably 1.5 to 2 times the total mass of the polyisocyanate, the polyhydroxy precursor, the woven node, and the ionic liquid.

[0012] The ionic liquid may include at least one of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, etc.

[0013] Based on the total mass of the polyisocyanate, the polyhydroxy precursor, the woven node, and the ionic liquid being 100%, the mass ratio of the ionic liquid may be 10% to 50%, such as 20%, 30%, 40%, etc., and preferably 20% to 40% to ensure the conductivity of the material and to balance the high strength and high toughness of the obtained ionic gel.

[0014] The polyisocyanate may be a diisocyanate precursor, specifically including at least one of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, etc.

[0015] Considering the influence of the hydroxyl type on its reaction activity with isocyanate, in some preferred embodiments, the hydroxyl groups in the polyhydroxy precursor and the woven node are both alcoholic hydroxyl groups.

[0016] The polyhydroxy precursor may be a dihydroxy precursor.

[0017] The polyhydroxy precursor described in the present invention includes ionic liquid monomers. The introduction of ionic liquid monomers can improve the compatibility between the polyurethane network and small molecule ionic liquids, and achieve high strength and high toughness of the ion gel. Further, the ionic liquid monomers include 1,3-bis(hydroxyethyl)imidazolium bis(trifluoromethanesulfonyl)imide, etc. The 1,3-bis(hydroxyethyl)imidazolium bis(trifluoromethanesulfonyl)imide has the following structure:

[0018]

[0019] The polyhydroxy precursor described in the present invention may further include polyols and chain extenders. The high-strength and high-toughness ion gel based on cross-linking of knitting nodes is a polyurethane ion gel. Polyols and chain extenders are common raw materials for preparing polyurethanes. Polyols are usually one of the soft segment components of polyurethanes, and chain extenders are usually one of the hard segment components of polyurethanes. The polyols may include at least one of polyester polyols and polyether polyols. In some embodiments, the polyether polyol includes polytetrahydrofuran (PTMG), etc., and the chain extender includes 1,4-butanediol (BDO), etc. Further, the number average molecular weight of the polytetrahydrofuran may be 1000-2000 g / mol.

[0020] The knitting node is a product of a three-dimensional cross-linked structure formed by the coordination reaction of a ligand and a copper(I) salt. The ligand is 1,10-phenanthroline having two or more hydroxyl-containing substituents and / or 2,2'-bipyridine having two or more hydroxyl-containing substituents.

[0021] In some embodiments, the preparation method of the knitting node includes: dropping a ligand solution into a copper(I) salt solution for reaction, and removing the solvent after the reaction is completed to obtain the knitting node. The solvent may include organic solvents, specifically including at least one of methanol, dichloromethane, acetonitrile, etc.

[0022] In some embodiments, the ligand is 1,10-phenanthroline having two hydroxyl-containing substituents. Further, the two hydroxyl-containing substituents may be respectively connected to the carbon atoms at the 2nd and 9th positions of 1,10-phenanthroline to ensure the formation of a three-dimensional cross-linked structure product by the coordination reaction with the copper(I) salt. Further still, the ligand may be 2,9-dihydroxymethylphenyl-1,10-phenanthroline. The 2,9-dihydroxymethylphenyl-1,10-phenanthroline has the following structure:

[0023]

[0024] The present invention herein provides a preferred preparation method of the 2,9-dihydroxymethylphenyl-1,10-phenanthroline, comprising: performing a Suzuki coupling reaction between 2,9-dichloro-1,10-phenanthroline and 4-hydroxymethylphenylboronic acid under the catalysis of tetrakis(triphenylphosphine)palladium, and then further obtaining purified 2,9-dihydroxymethylphenyl-1,10-phenanthroline through column chromatography separation.

[0025] The copper(I) salt may include at least one of copper tetraethylacetonitrile tetrafluoroborate, copper tetraethylacetonitrile hexafluorophosphate, etc., and preferably includes copper tetraethylacetonitrile tetrafluoroborate.

[0026] The molar ratio of Cu in the ligand and the copper(I) salt + may be 2:1.

[0027] The molar ratio of the isocyanate functional group of the polyisocyanate to the total amount of the hydroxyl groups of the polyhydroxy precursor and the hydroxyl groups of the weaving node may be 1:1.

[0028] Based on the total mass of the polyisocyanate, the polyhydroxy precursor and the weaving node being 100%, the mass proportion of the weaving node may be 1% to 20%, preferably 3% to 6% to maintain a suitable crosslinking density of the material, so that the ion gel has both high strength and high toughness.

[0029] For the preparation method of the high-strength and high-toughness ion gel crosslinked based on the weaving node, the copolymerization temperature may be room temperature to 80°C, such as 60°C, etc., and the copolymerization time may be 2 to 72 h.

[0030] In some embodiments, the preparation method of the high-strength and high-toughness ion gel crosslinked based on the weaving node specifically includes:

[0031] Step 1, with or without the presence of a catalyst, pre-polymerize the weaving node, polyol and polyisocyanate in an organic solvent to form a pre-polymerization mixture;

[0032] Step 2, add an ionic liquid, an ionic liquid monomer and a chain extender to the pre-polymerization mixture, continue polymerization to form a polymer network, and then remove the organic solvent to obtain a high-strength and high-toughness polyurethane ion gel crosslinked based on the weaving node.

[0033] Further, in Step 2, the ionic liquid, the ionic liquid monomer and the chain extender may be added sequentially.

[0034] [2] A high-strength and high-toughness ion gel crosslinked based on the weaving node prepared by the preparation method according to [1].

[0035] The present invention provides a method for crosslinking polyurethane chains through the knitting nodes of a cross structure, using the cross structure as the framework of an ion gel, and taking advantage of the dynamic and interlocking characteristics of the cross-knitting nodes to form an ion gel material with both high strength and high toughness.

[0036] [3] Application of the high-strength and high-toughness ion gel crosslinked based on knitting nodes in flexible electronic materials according to [2].

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] The present invention discloses an ion gel material with both high strength and high toughness and a preparation method thereof. For example, hexamethylene diisocyanate, polytetrahydrofuran, 1,4-butanediol, and an ionic liquid monomer form polyurethane chains through addition polymerization, and at the same time, the introduced 1,10-bis(hydroxymethyl)phenanthroline knitting nodes achieve the crosslinking of polyurethane chains, forming a knitted interlocking polyurethane network. Based on the dynamics of coordination bonds, the polyurethane network can dissipate energy when subjected to external forces, thereby protecting the polyurethane chain segments from damage; on the other hand, the interlocking feature endows the polyurethane network with structural stability and maintains the high strength of the knitted interlocking polyurethane ion gel material. Therefore, the knitted interlocking polyurethane ion gel has both high strength and toughness, thereby broadening its application scope and service life. Description of the Drawings

[0039] Figure 1 1H nuclear magnetic resonance ( 1 1H NMR) spectrum of the 2,9-bis(hydroxymethyl)phenyl-1,10-phenanthroline ligand prepared in Example 1.

[0040] Figure 2 1H NMR spectrum of the knitting nodes prepared in Example 1 1 1H NMR spectrum.

[0041] Figure 3 1H NMR spectrum of 4,7-bis(hydroxymethyl)phenyl-1,10-phenanthroline prepared in Comparative Example 1 1 1H NMR spectrum.

[0042] Figure 4 1H NMR spectrum of 1,3,6,8-tetrakis(hydroxymethyl)pyrene prepared in Comparative Example 2 1 1H NMR spectrum.

[0043] Figure 5 Fourier transform infrared (FTIR) spectra of the polyurethane ion gels prepared in Example 1 (WIG-30%), Comparative Example 1 (SIG-30%), and Comparative Example 2 (CIG-30%).

[0044] Figure 6Thermogravimetric (TGA) curves of the polyurethane ion gels prepared in Example 1 (WIG-30%), Comparative Example 1 (SIG-30%), and Comparative Example 2 (CIG-30%).

[0045] Figure 7 Stress-strain curves of the polyurethane ion gels prepared in Example 1 (WIG-30%), Comparative Example 1 (SIG-30%), and Comparative Example 2 (CIG-30%).

[0046] Figure 8 Stress-strain curves of the polyurethane ion gels prepared in Example 1 (WIG-30%), Example 2 (WIG-20%), Example 3 (WIG-40%), and Example 4 (WIG-50%).

[0047] Figure 9 Cyclic tensile curve of the polyurethane ion gel prepared in Example 1 (WIG-30%).

[0048] Figure 10 Cyclic tensile curve of the polyurethane ion gel prepared in Comparative Example 1 (SIG-30%).

[0049] Figure 11 Cyclic tensile curve of the polyurethane ion gel prepared in Comparative Example 2 (CIG-30%). Detailed implementation mode

[0050] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. The operating methods without specific conditions noted in the following embodiments are usually in accordance with conventional conditions or in accordance with the conditions recommended by the manufacturer.

[0051] Example 1:

[0052] Preparation of 2,9-dihydroxymethylphenyl-1,10-phenanthroline weaving nodes: 2,9-dichloro-1,10-phenanthroline (2.00 g, 8.03 mmol), 4-hydroxymethylphenylboronic acid (3.05 g, 20.07 mmol) and sodium carbonate (3.40 g, 31.12 mmol) were dispersed in a mixture of ethylene glycol dimethyl ether and water (50 mL, volume ratio 4:1). After evacuating three times by vacuum, under nitrogen protection, tetrakis(triphenylphosphine)palladium (0.93 g, 0.80 mmol) was added to catalyze the reaction. After the reaction was carried out at 96 °C for 48 hours, 2,9-dihydroxymethylphenyl-1,10-phenanthroline was obtained by column chromatography separation. At room temperature, 2,9-dihydroxymethylphenyl-1,10-phenanthroline (1.00 g, 2.55 mmol) was dissolved in a mixture of methanol and dichloromethane (400 mL, volume ratio 1:1), and then dropped into an acetonitrile solution (80 mL) of copper(II) bis(tetrafluoroborate) bis(acetonitrile) (0.40 g, 1.275 mmol). After the dropping was completed, stirring was continued for 3 hours, and then the organic solvents were removed by rotary evaporation to obtain 2,9-dihydroxymethylphenyl-1,10-phenanthroline weaving nodes.

[0053] Preparation of woven interlocked polyurethane ion gel: 2,9-dihydroxymethylphenyl-1,10-phenanthroline weaving nodes (152.4 mg, 0.16 mmol), polytetrahydrofuran (1.20 g, 0.60 mmol) and hexamethylene diisocyanate (0.58 g, 3.45 mmol) were dissolved in DMF (8 mL) and stirred evenly, and then the catalyst dibutyltin dilaurate (DBTDL, 0.1% of the total weight of polyisocyanate, polyhydroxy precursor and weaving nodes) was added. After prepolymerization at 60 °C for 2 hours, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (1.13 g), ionic liquid monomer 1,3-bis(2-hydroxyethyl)imidazolium bis(trifluoromethanesulfonyl)imide salt (0.61 g, 1.40 mmol) and 1,4-butanediol (102.0 mg, 1.13 mmol) were added in sequence. After continuing to polymerize at 60 °C for 30 minutes, it was transferred to a polytetrafluoroethylene mold, and the organic solvents were removed by air drying and vacuum treatment to form a woven interlocked polyurethane ion gel, denoted as WIG-30% (30% is the mass fraction of ionic liquid in the ion gel).

[0054] Comparative Example 1:

[0055] Preparation of 4,7-bis(hydroxymethyl)phenyl-1,10-phenanthroline: 4,7-Dibromo-1,10-phenanthroline (1.4 g, 4.14 mmol), 4-(hydroxymethyl)phenylboronic acid (1.76 g, 11.60 mmol) and potassium carbonate (2.18 g, 15.74 mmol) were dispersed in a mixture of 1,4-dioxane and water (40 mL, volume ratio 4:1). After evacuating three times under vacuum, under nitrogen protection, tetrakis(triphenylphosphine)palladium (0.48 g, 0.41 mmol) was added to catalyze the reaction. After the reaction was carried out at 100 °C for 5 days, 4,7-bis(hydroxymethyl)phenyl-1,10-phenanthroline was obtained by column chromatography separation.

[0056] Preparation of supramolecular crosslinked polyurethane ion gel: 4,7-Bis(hydroxymethyl)phenyl-1,10-phenanthroline (127.9 mg, 0.33 mmol), polytetrahydrofuran (1.20 g, 0.60 mmol) and hexamethylene diisocyanate (0.58 g, 3.45 mmol) were dissolved in DMF (8 mL) and stirred evenly, and then dibutyltin dilaurate (DBTDL, 0.1% of the total weight of polyisocyanate, polyhydroxy precursor and knitting node) was added as a catalyst. After pre-polymerization at 60 °C for 2 hours, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (1.13 g), ionic liquid monomer 1,3-bis(2-hydroxyethyl)imidazolium bis(trifluoromethanesulfonyl)imide salt (0.61 g, 1.40 mmol) and 1,4-butanediol (102.0 mg, 1.13 mmol) were added in sequence. After continuing to polymerize at 60 °C for 30 minutes, copper(II) tetraethylammonium tetrafluoroborate (51.2 mg, 0.165 mol) was added to form a supramolecular crosslinked polyurethane network. It was transferred to a polytetrafluoroethylene mold and dried by blowing and vacuum-treated to remove organic solvents to form a supramolecular crosslinked polyurethane ion gel, denoted as SIG-30% (30% is the mass fraction of ionic liquid in the ion gel).

[0057] Comparative Example 2:

[0058] Preparation of 1,3,6,8-tetrakis(hydroxymethyl)phenylpyrene: 1,3,6,8-Tetrabromopyrene (1.50 g, 2.90 mmol), 4-(hydroxymethyl)phenylboronic acid (2.29 g, 15.06 mmol) and potassium carbonate (2.80 g, 20.28 mmol) were dispersed in a mixture of 1,4-dioxane and water (40 mL, volume ratio 3:1). After evacuating three times under vacuum, under nitrogen protection, tetrakis(triphenylphosphine)palladium (1.34 g, 1.16 mmol) was added to catalyze the reaction. After the reaction was carried out at 100 °C for 72 hours, 1,3,6,8-tetrakis(hydroxymethyl)phenylpyrene was obtained by column chromatography separation.

[0059] Preparation of covalently crosslinked polyurethane ion gel: 1,3,6,8 - tetrahydroxymethylpyrene (102.2 mg, 0.16 mmol), polytetrahydrofuran (1.2 g, 0.6 mmol) and hexamethylene diisocyanate (0.58 g, 3.45 mmol) were dissolved in DMF (8 mL) and stirred evenly, then the catalyst dibutyltin dilaurate (DBTDL, 0.1% of the total weight of polyisocyanate, polyhydroxy precursor and woven nodes) was added. After prepolymerization at 60 °C for 2 hours, 1 - ethyl - 3 - methylimidazolium bis(trifluoromethylsulfonyl)imide (1.11 g), ionic liquid monomer 1,3 - bis(2 - hydroxyethyl)imidazolium bis(trifluoromethanesulfonyl)imide salt (0.61 g, 1.4 mmol) and 1,4 - butanediol (102.0 mg, 1.13 mmol) were added in sequence. After polymerization at 60 °C for 30 minutes, it was transferred to a polytetrafluoroethylene mold, and the organic solvent was removed by air drying and vacuum treatment to form a covalently crosslinked polyurethane ion gel, denoted as CIG - 30% (30% is the mass fraction of ionic liquid in the ion gel).

[0060] Example 2:

[0061] The difference from Example 1 is only that the amount of 1 - ethyl - 3 - methylimidazolium bis(trifluoromethylsulfonyl)imide in the feed ratio of the polymerization reaction was changed from 1.13 g to 0.66 g, and the rest were the same. At this ratio, the weight ratio of the small - molecule ionic liquid is 20%, and the obtained woven interlocked polyurethane ion gel is denoted as WIG - 20%.

[0062] Example 3:

[0063] The difference from Example 1 is only that the amount of 1 - ethyl - 3 - methylimidazolium bis(trifluoromethylsulfonyl)imide in the feed ratio of the polymerization reaction was changed from 1.13 g to 1.76 g, and the rest were the same. At this ratio, the weight ratio of the small - molecule ionic liquid is 40%, and the obtained woven interlocked polyurethane ion gel is denoted as WIG - 40%.

[0064] Example 4:

[0065] The difference from Example 1 is only that the amount of 1 - ethyl - 3 - methylimidazolium bis(trifluoromethylsulfonyl)imide in the feed ratio of the polymerization reaction was changed from 1.13 g to 2.64 g, and the rest were the same. At this ratio, the weight ratio of the small - molecule ionic liquid is 50%, and the obtained woven interlocked polyurethane ion gel is denoted as WIG - 50%.

[0066] Figures 1 to 41H NMR spectra of 2,9-dihydroxymethylphenyl-1,10-phenanthroline ligand and woven nodes prepared in Example 1, 4,7-dihydroxymethylphenyl-1,10-phenanthroline prepared in Comparative Example 1, and pyrene tetramethanol prepared in Comparative Example 2 1 The chemical shifts of each proton in the figure are consistent with the structural formula of the designed compound, indicating that the 2,9-dihydroxymethylphenyl-1,10-phenanthroline woven node compound and the compounds used for supramolecular crosslinking and covalent crosslinking in the comparative examples were successfully prepared.

[0067] Figure 5 FTIR spectra of polyurethane ion gels prepared in Example 1 (WIG-30%), Comparative Example 1 (SIG-30%), and Comparative Example 2 (CIG-30%). In the present invention, polyurethane ion gels were prepared by addition polymerization. After the addition polymerization reaction was completed, the absorption peak at 2200-2300 cm -1 disappeared, indicating that the isocyanate had completely reacted, and the absorption peak of hydroxyl groups was not observed at 3400-3500 cm -1 either, indicating that polyurethane ion gels were successfully prepared by addition polymerization.

[0068] Figure 6 TGA curves of polyurethane ion gels prepared in Example 1 (WIG-30%), Comparative Example 1 (SIG-30%), and Comparative Example 2 (CIG-30%). The three showed similar changing trends, which should be attributed to the fact that except for the crosslinking points, the three had similar compositions.

[0069] Figure 7 Stress-strain curves of polyurethane ion gels prepared in Example 1 (WIG-30%), Comparative Example 1 (SIG-30%), and Comparative Example 2 (CIG-30%). It can be seen from the figure that compared with supramolecular crosslinked and covalently crosslinked polyurethane ion gels, the woven interlocked polyurethane ion gels crosslinked by woven nodes showed higher tensile strength, elongation at break, and toughness. For SIG-30%, its tensile strength, elongation at break, and toughness were 7.9 MPa, 2600%, and 89.7 MJ / m 3 respectively. For CIG-30%, its tensile strength, elongation at break, and toughness were 6.0 MPa, 2200%, and 79.1 MJ / m 3 respectively. For WIG-30%, its tensile strength, elongation at break, and toughness were 23.2 MPa, 4900%, and 473.8 MJ / m 3The polyurethane ion gel material with cross-linked knitting nodes shows simultaneous improvement in tensile strength, elongation at break, and toughness, indicating that the formation of the knitted interlocking network endows the polyurethane ion gel material with excellent dynamics and structural stability.

[0070] Figure 8 Stress-strain curves of polyurethane ion gels were prepared for Example 1 (WIG-30%), Example 2 (WIG-20%), Example 3 (WIG-40%), and Example 4 (WIG-50%). It can be seen from the figure that the polyurethane ion gel exhibits high strength and high toughness. As the content of the ionic liquid increases (20% → 50%), its tensile strength shows a downward trend (33.5 MPa → 2.8 MPa), which is attributed to the solvation effect of the ionic liquid on the polyurethane segments. The elongation at break shows a trend of increasing first and then decreasing, reaching a maximum value (5500%) when the ionic liquid content is 40%. This should be because the increase in the ionic liquid content increases the slip ability of the polyurethane segments, resulting in an increase in the elongation at break. However, too much ionic liquid leads to a decrease in the cross-linking density of the polymer network, and the polyurethane segments are easily detached after slipping, causing the elongation at break to decrease.

[0071] Figures 9 to 11 Cyclic tensile curves of Example 1 (WIG-30%), Comparative Example 1 (SIG-30%), and Comparative Example 2 (CIG-30%) are shown. It can be seen from the figure that WIG-30% shows lower hysteresis at different strains, which provides better support for its application as a flexible electronic material.

[0072] It can be seen that in the present invention, hexamethylene diisocyanate, polytetrahydrofuran, ionic liquid monomer, and knitting nodes are dissolved in a mixture of N,N-dimethylformamide and ionic liquid, and under the catalytic condition of dibutyltin dilaurate, a knitted interlocking ion gel material with both high strength and high toughness is formed through an addition polymerization reaction. The present invention endows the ion gel material with good dynamics and structural stability through the knitted interlocking network, enabling it to effectively dissipate energy when subjected to external forces, and endowing the material with high strength by utilizing its interlocking structural stability, thus simultaneously showing high strength and high toughness.

[0073] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

Claims

1. A preparation method of a high-strength and high-toughness ionic gel based on crosslinking of knitting nodes, characterized in that, Comprising: In the presence or absence of a catalyst, a polyisocyanate, a polyhydroxy precursor, and a woven node are copolymerized in a dispersion medium containing an organic solvent and an ionic liquid to form a polymer network, and then the organic solvent is removed to obtain the high-strength and high-toughness ionic gel crosslinked based on the woven node; The polyhydroxy precursor includes an ionic liquid monomer; The woven node is a product of a three-dimensional cross-linked structure formed by the coordination reaction of a ligand and a copper(I) salt, and the ligand is 1,10-phenanthroline having two or more hydroxyl-containing substituents and / or 2,2'-bipyridine having two or more hydroxyl-containing substituents.

2. The preparation method of the high-strength and high-toughness ion gel based on crosslinking of weaving nodes according to claim 1, wherein The ionic liquid includes at least one of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-propyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide; Based on the total mass of the polyisocyanate, the polyhydroxy precursor, the woven node, and the ionic liquid being 100%, the mass ratio of the ionic liquid is 10% - 50%, preferably 20% - 40%.

3. The preparation method of the high-strength and high-toughness ion gel based on crosslinking of knitting nodes according to claim 1, characterized in that The hydroxyl groups in the polyhydroxy precursor and the woven node are all alcoholic hydroxyl groups; The ionic liquid monomer includes 1,3-bis(hydroxyethyl)imidazolium bis(trifluoromethanesulfonyl)imide salt.

4. The preparation method of the high-strength and high-toughness ion gel based on cross-linking of weaving nodes according to claim 1, wherein, The polyhydroxy precursor further includes a polyol and a chain extender; The polyol includes at least one of a polyester polyol and a polyether polyol; The polyether polyol includes polytetrahydrofuran; the number-average molecular weight of the polytetrahydrofuran is 1000 - 2000 g / mol; The chain extender includes 1,4-butanediol.

5. The preparation method of the high-strength and high-toughness ionic gel based on woven node crosslinking according to claim 1, characterized in that The ligand is 1,10-phenanthroline having two hydroxyl-containing substituents; The two hydroxyl-containing substituents are respectively connected to the carbon atoms at the 2nd and 9th positions of 1,10-phenanthroline; The ligand is 2,9-dihydroxymethylphenyl-1,10-phenanthroline; The copper(I) salt includes at least one of copper tetraethylacetonitrile tetrafluoroborate and copper tetraethylacetonitrile hexafluorophosphate; The molar ratio of Cu in the ligand and the copper(I) salt is 2:

1. + ​ 6. The preparation method of the high-strength and high-toughness ion gel based on cross-linking of knitting nodes according to claim 1, characterized in that, The molar ratio of the isocyanate functional group of the polyisocyanate to the total amount of the hydroxyl groups of the polyhydroxy precursor and the woven node is 1:1; Based on the total mass of the polyisocyanate, the polyhydroxy precursor, and the woven node being 100%, the mass ratio of the woven node is 1% - 20%, preferably 3% - 6%.

7. The preparation method of the high-strength and high-toughness ion gel based on crosslinking of knitting nodes according to claim 1, characterized in that The copolymerization temperature is room temperature to 80 °C, and the copolymerization time is 2 - 72 h.

8. The preparation method of the high-strength and high-toughness ion gel based on crosslinking of weaving nodes according to claim 4, characterized in that The preparation method of the high-strength and high-toughness ionic gel crosslinked based on the woven node specifically includes: Step 1, in the presence or absence of a catalyst, the woven node, the polyol, and the polyisocyanate are pre-polymerized in an organic solvent to form a pre-polymerization mixture; Step 2, an ionic liquid, an ionic liquid monomer, and a chain extender are added to the pre-polymerization mixture, and polymerization is continued to form a polymer network, and then the organic solvent is removed to obtain a high-strength and high-toughness polyurethane ionic gel crosslinked based on the woven node.

9. A high-strength and high-toughness ionic gel crosslinked based on a woven node prepared by the preparation method according to any one of claims 1 - 8.

10. Application of the high-strength and high-toughness ionic gel crosslinked based on a woven node according to claim 9 in flexible electronic materials.

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